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* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
@ 2014-08-20 19:13 Josh Berkus <josh@agliodbs.com>
2014-08-20 20:36 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Shaun Thomas <sthomas@optionshouse.com>
2014-08-20 23:14 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
0 siblings, 3 replies; 26+ messages in thread
From: Josh Berkus @ 2014-08-20 19:13 UTC (permalink / raw)
To: pgsql-performance; +Cc: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
Mark, all:
So, this is pretty damming:
Read-only test with HT ON:
[pgtest@db ~]$ pgbench -c 20 -j 4 -T 600 -S bench
starting vacuum...end.
transaction type: SELECT only
scaling factor: 30
query mode: simple
number of clients: 20
number of threads: 4
duration: 600 s
number of transactions actually processed: 47167533
tps = 78612.471802 (including connections establishing)
tps = 78614.604352 (excluding connections establishing)
Read-only test with HT Off:
[pgtest@db ~]$ pgbench -c 20 -j 4 -T 600 -S bench
starting vacuum...end.
transaction type: SELECT only
scaling factor: 30
query mode: simple
number of clients: 20
number of threads: 4
duration: 600 s
number of transactions actually processed: 82457739
tps = 137429.508196 (including connections establishing)
tps = 137432.893796 (excluding connections establishing)
On a read-write test, it's 10% faster with HT off as well.
Further, from their production machine we've seen that having HT on
causes the machine to slow down by 5X whenever you get more than 40
cores (as in 100% of real cores or 50% of HT cores) worth of activity.
So we're definitely back to "If you're using PostgreSQL, turn off
Hyperthreading".
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-20 20:36 ` Shaun Thomas <sthomas@optionshouse.com>
2014-08-20 23:59 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Peter Geoghegan <peter.geoghegan86@gmail.com>
2 siblings, 1 reply; 26+ messages in thread
From: Shaun Thomas @ 2014-08-20 20:36 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; pgsql-performance; +Cc: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On 08/20/2014 02:13 PM, Josh Berkus wrote:
> So we're definitely back to "If you're using PostgreSQL, turn off
> Hyperthreading".
That's so strange. Back when I did my Nehalem tests, we got a very
strong 30%+ increase by enabling HT. We only got a hit when we turned
off turbo, or forgot to disable power saving features.
--
Shaun Thomas
OptionsHouse, LLC | 141 W. Jackson Blvd. | Suite 800 | Chicago IL, 60604
312-676-8870
sthomas@optionshouse.com
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-20 20:36 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Shaun Thomas <sthomas@optionshouse.com>
@ 2014-08-20 23:59 ` Peter Geoghegan <peter.geoghegan86@gmail.com>
0 siblings, 0 replies; 26+ messages in thread
From: Peter Geoghegan @ 2014-08-20 23:59 UTC (permalink / raw)
To: Shaun Thomas <sthomas@optionshouse.com>; +Cc: Josh Berkus <josh@agliodbs.com>; pgsql-performance; Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On Wed, Aug 20, 2014 at 1:36 PM, Shaun Thomas <sthomas@optionshouse.com> wrote:
> That's so strange. Back when I did my Nehalem tests, we got a very strong
> 30%+ increase by enabling HT. We only got a hit when we turned off turbo, or
> forgot to disable power saving features.
In my experience, it is crucially important to consider power saving
features in most benchmarks these days, where that might not have been
true a few years ago. The CPU scaling governor can alter the outcome
of many benchmarks quite significantly.
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Peter Geoghegan
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-20 23:14 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2014-08-21 10:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2014-08-21 14:14 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Shaun Thomas <sthomas@optionshouse.com>
2 siblings, 2 replies; 26+ messages in thread
From: Mark Kirkwood @ 2014-08-20 23:14 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; pgsql-performance; +Cc: Graeme B. Bell <grb@skogoglandskap.no>
On 21/08/14 07:13, Josh Berkus wrote:
> Mark, all:
>
> So, this is pretty damming:
>
> Read-only test with HT ON:
>
> [pgtest@db ~]$ pgbench -c 20 -j 4 -T 600 -S bench
> starting vacuum...end.
> transaction type: SELECT only
> scaling factor: 30
> query mode: simple
> number of clients: 20
> number of threads: 4
> duration: 600 s
> number of transactions actually processed: 47167533
> tps = 78612.471802 (including connections establishing)
> tps = 78614.604352 (excluding connections establishing)
>
> Read-only test with HT Off:
>
> [pgtest@db ~]$ pgbench -c 20 -j 4 -T 600 -S bench
> starting vacuum...end.
> transaction type: SELECT only
> scaling factor: 30
> query mode: simple
> number of clients: 20
> number of threads: 4
> duration: 600 s
> number of transactions actually processed: 82457739
> tps = 137429.508196 (including connections establishing)
> tps = 137432.893796 (excluding connections establishing)
>
>
> On a read-write test, it's 10% faster with HT off as well.
>
> Further, from their production machine we've seen that having HT on
> causes the machine to slow down by 5X whenever you get more than 40
> cores (as in 100% of real cores or 50% of HT cores) worth of activity.
>
> So we're definitely back to "If you're using PostgreSQL, turn off
> Hyperthreading".
>
Hmm - that is interesting - I don't think we compared read only scaling
for hyperthreading on and off (only read write). You didn't mention what
cpu this is for (or how many sockets etc), would be useful to know.
Notwithstanding the above results, my workmate Matt made an interesting
observation: the scaling graph for (our) 60 core box (HT off), looks
just like the one for our 32 core box with HT *on*.
We are wondering if a lot of the previous analysis of HT performance
regressions should actually be reevaluated in the light of ...err is it
just that we have a lot more cores...? [1]
Regards
Mark
[1] Particularly as in *some* cases (single socket i7 for instance) HT
on seems to scale fine.
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-20 23:14 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
@ 2014-08-21 10:02 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
1 sibling, 0 replies; 26+ messages in thread
From: Mark Kirkwood @ 2014-08-21 10:02 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; pgsql-performance; +Cc: Graeme B. Bell <grb@skogoglandskap.no>
On 21/08/14 11:14, Mark Kirkwood wrote:
>
> You didn't mention what
> cpu this is for (or how many sockets etc), would be useful to know.
>
Just to clarify - while you mentioned that the production system was 40
cores, it wasn't immediately obvious that the same system was the source
of the measurements you posted...sorry if I'm being a mixture of
pedantic and dense - just trying to make sure it is clear what
systems/cpus etc we are talking about (with this in mind it never hurts
to quote cpu and mobo model numbers)!
Cheers
Mark
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-20 23:14 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
@ 2014-08-21 14:14 ` Shaun Thomas <sthomas@optionshouse.com>
1 sibling, 0 replies; 26+ messages in thread
From: Shaun Thomas @ 2014-08-21 14:14 UTC (permalink / raw)
To: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Josh Berkus <josh@agliodbs.com>; pgsql-performance; +Cc: Graeme B. Bell <grb@skogoglandskap.no>
On 08/20/2014 06:14 PM, Mark Kirkwood wrote:
> Notwithstanding the above results, my workmate Matt made an interesting
> observation: the scaling graph for (our) 60 core box (HT off), looks
> just like the one for our 32 core box with HT *on*.
Hmm. I know this sounds stupid and unlikely, but has anyone actually
tested PostgreSQL on a system with more than 64 legitimate cores? The
work Robert Haas did to fix the CPU locking way back when showed
significant improvements up to 64, but so far as I know, nobody really
tested beyond that.
I seem to remember similar choking effects when pre-9.2 systems
encountered high CPU counts. I somehow doubt Intel would allow their HT
architecture to regress so badly from Nehalem, which is almost
3-generations old at this point. This smells like something in the
software stack, up to and including the Linux kernel.
--
Shaun Thomas
OptionsHouse, LLC | 141 W. Jackson Blvd. | Suite 800 | Chicago IL, 60604
312-676-8870
sthomas@optionshouse.com
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-21 02:40 ` Bruce Momjian <bruce@momjian.us>
2014-08-21 02:47 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Tatsuo Ishii <ishii@postgresql.org>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2 siblings, 2 replies; 26+ messages in thread
From: Bruce Momjian @ 2014-08-21 02:40 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; +Cc: pgsql-performance@postgresql.org, Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On Wed, Aug 20, 2014 at 12:13:50PM -0700, Josh Berkus wrote:
> On a read-write test, it's 10% faster with HT off as well.
>
> Further, from their production machine we've seen that having HT on
> causes the machine to slow down by 5X whenever you get more than 40
> cores (as in 100% of real cores or 50% of HT cores) worth of activity.
>
> So we're definitely back to "If you're using PostgreSQL, turn off
> Hyperthreading".
Not sure how you can make such a blanket statement when so many people
have tested and shown the benefits of hyper-threading. I am also
unclear exactly what you tested, as I didn't see it mentioned in the
email --- CPU type, CPU count, and operating system would be the minimal
information required.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ Everyone has their own god. +
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
@ 2014-08-21 02:47 ` Tatsuo Ishii <ishii@postgresql.org>
2014-08-21 20:03 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Graeme B. Bell <grb@skogoglandskap.no>
1 sibling, 1 reply; 26+ messages in thread
From: Tatsuo Ishii @ 2014-08-21 02:47 UTC (permalink / raw)
To: bruce@momjian.us; +Cc: josh@agliodbs.com; pgsql-performance; mark.kirkwood@catalyst.net.nz; grb@skogoglandskap.no
> On Wed, Aug 20, 2014 at 12:13:50PM -0700, Josh Berkus wrote:
>> On a read-write test, it's 10% faster with HT off as well.
>>
>> Further, from their production machine we've seen that having HT on
>> causes the machine to slow down by 5X whenever you get more than 40
>> cores (as in 100% of real cores or 50% of HT cores) worth of activity.
>>
>> So we're definitely back to "If you're using PostgreSQL, turn off
>> Hyperthreading".
>
> Not sure how you can make such a blanket statement when so many people
> have tested and shown the benefits of hyper-threading. I am also
> unclear exactly what you tested, as I didn't see it mentioned in the
> email --- CPU type, CPU count, and operating system would be the minimal
> information required.
HT off is common knowledge for better benchmarking result, at least
for me. I've never seen better result with HT on, except POWER.
Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 02:47 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Tatsuo Ishii <ishii@postgresql.org>
@ 2014-08-21 20:03 ` Graeme B. Bell <grb@skogoglandskap.no>
0 siblings, 0 replies; 26+ messages in thread
From: Graeme B. Bell @ 2014-08-21 20:03 UTC (permalink / raw)
To: Tatsuo Ishii <ishii@postgresql.org>; +Cc: bruce@momjian.us <bruce@momjian.us>; josh@agliodbs.com <josh@agliodbs.com>; pgsql-performance; mark.kirkwood@catalyst.net.nz <mark.kirkwood@catalyst.net.nz>
> HT off is common knowledge for better benchmarking result
It's wise to use the qualifer 'for better benchmarking results'.
It's worth keeping in mind here that a benchmark is not the same as normal production use.
For example, where I work we do lots of long-running queries in parallel over a big range of datasets rather than many short-term transactions as fast as possible. Our biggest DB server is also used for GDAL work and R at the same time*. Pretty far from pgbench; not everyone is constrained by locks.
I suppose that if your code is basically N copies of the same function, hyper-threading isn't likely to help much because it was introduced to allow different parts of the processor to be used in parallel when you're running hetarogenous code.
But if you're hammering just one part of the CPU... well, adding another layer of logical complexity for your CPU to manage probably isn't going to do much good.
Should HT be on or off when you're running 64 very mixed types of long-term queries which involve variously either heavy use of real number calculations or e.g. logic/string handling, and different data sets? It's a much more complex question than simply maxing out your pgbench scores.
I don't have the data now unfortunately, but I remember seeing a benefit for HT on our 4 core e3 when running GDAL/Postgis work in parallel last year. It's not surprising though; the GDAL calls are almost certainly using different functions of the processor compared to postgres and there should be very little lock contention. In light of this interesting data I'm now leaning towards proposing HT off for our mapservers (which receive short, similar requests over and over), but for the hetaragenous servers, I think I'll keep it on for now.
Graeme.
* unrelated. There's also huge advantages for us in keeping these different programs running on the same machine since we found we can get much better transfer rates through unix sockets than with TCP over the network.
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
@ 2014-08-21 21:02 ` Josh Berkus <josh@agliodbs.com>
2014-08-21 21:11 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:26 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Scott Marlowe <scott.marlowe@gmail.com>
2014-08-22 14:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Andres Freund <andres@2ndquadrant.com>
1 sibling, 3 replies; 26+ messages in thread
From: Josh Berkus @ 2014-08-21 21:02 UTC (permalink / raw)
To: Bruce Momjian <bruce@momjian.us>; +Cc: pgsql-performance@postgresql.org, Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On 08/20/2014 07:40 PM, Bruce Momjian wrote:
> On Wed, Aug 20, 2014 at 12:13:50PM -0700, Josh Berkus wrote:
>> On a read-write test, it's 10% faster with HT off as well.
>>
>> Further, from their production machine we've seen that having HT on
>> causes the machine to slow down by 5X whenever you get more than 40
>> cores (as in 100% of real cores or 50% of HT cores) worth of activity.
>>
>> So we're definitely back to "If you're using PostgreSQL, turn off
>> Hyperthreading".
>
> Not sure how you can make such a blanket statement when so many people
> have tested and shown the benefits of hyper-threading.
Actually, I don't know that anyone has posted the benefits of HT. Link?
I want to compare results so that we can figure out what's different
between my case and theirs. Also, it makes a big difference if there is
an advantage to turning HT on for some workloads.
> I am also
> unclear exactly what you tested, as I didn't see it mentioned in the
> email --- CPU type, CPU count, and operating system would be the minimal
> information required.
Ooops! I thought I'd posted that earlier, but I didn't.
The processors in question is the Intel(R) Xeon(R) CPU E7- 4850, with 4
of them for a total of 40 cores or 80 HT cores.
OS is RHEL with 2.6.32-431.3.1.el6.x86_64.
I've emailed a kernel hacker who works at Intel for comment; for one
thing, I'm wondering if the older kernel version is a problem for a
system like this.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-21 21:11 ` Bruce Momjian <bruce@momjian.us>
2014-08-21 21:17 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2 siblings, 1 reply; 26+ messages in thread
From: Bruce Momjian @ 2014-08-21 21:11 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; +Cc: pgsql-performance@postgresql.org, Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>; Greg Smith <gregsmithpgsql@gmail.com>
On Thu, Aug 21, 2014 at 02:02:26PM -0700, Josh Berkus wrote:
> On 08/20/2014 07:40 PM, Bruce Momjian wrote:
> > On Wed, Aug 20, 2014 at 12:13:50PM -0700, Josh Berkus wrote:
> >> On a read-write test, it's 10% faster with HT off as well.
> >>
> >> Further, from their production machine we've seen that having HT on
> >> causes the machine to slow down by 5X whenever you get more than 40
> >> cores (as in 100% of real cores or 50% of HT cores) worth of activity.
> >>
> >> So we're definitely back to "If you're using PostgreSQL, turn off
> >> Hyperthreading".
> >
> > Not sure how you can make such a blanket statement when so many people
> > have tested and shown the benefits of hyper-threading.
>
> Actually, I don't know that anyone has posted the benefits of HT. Link?
> I want to compare results so that we can figure out what's different
> between my case and theirs. Also, it makes a big difference if there is
> an advantage to turning HT on for some workloads.
I had Greg Smith test my system when it was installed, tested it, and
recommended hyper-threading. The system is Debian Squeeze
(2.6.32-5-amd64), CPUs are dual Xeon E5620, 8 cores, 16 virtual cores.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ Everyone has their own god. +
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 21:11 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
@ 2014-08-21 21:17 ` Josh Berkus <josh@agliodbs.com>
2014-08-21 21:26 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
0 siblings, 1 reply; 26+ messages in thread
From: Josh Berkus @ 2014-08-21 21:17 UTC (permalink / raw)
To: Bruce Momjian <bruce@momjian.us>; +Cc: pgsql-performance@postgresql.org, Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>; Greg Smith <gregsmithpgsql@gmail.com>
On 08/21/2014 02:11 PM, Bruce Momjian wrote:
> On Thu, Aug 21, 2014 at 02:02:26PM -0700, Josh Berkus wrote:
>> On 08/20/2014 07:40 PM, Bruce Momjian wrote:
>>> On Wed, Aug 20, 2014 at 12:13:50PM -0700, Josh Berkus wrote:
>>>> On a read-write test, it's 10% faster with HT off as well.
>>>>
>>>> Further, from their production machine we've seen that having HT on
>>>> causes the machine to slow down by 5X whenever you get more than 40
>>>> cores (as in 100% of real cores or 50% of HT cores) worth of activity.
>>>>
>>>> So we're definitely back to "If you're using PostgreSQL, turn off
>>>> Hyperthreading".
>>>
>>> Not sure how you can make such a blanket statement when so many people
>>> have tested and shown the benefits of hyper-threading.
>>
>> Actually, I don't know that anyone has posted the benefits of HT. Link?
>> I want to compare results so that we can figure out what's different
>> between my case and theirs. Also, it makes a big difference if there is
>> an advantage to turning HT on for some workloads.
>
> I had Greg Smith test my system when it was installed, tested it, and
> recommended hyper-threading. The system is Debian Squeeze
> (2.6.32-5-amd64), CPUs are dual Xeon E5620, 8 cores, 16 virtual cores.
Can you post some numerical results?
I'm serious. It's obviously easier for our users if we can blanket
recommend turning HT off; that's a LOT easier for them than "you might
want to turn HT off if these conditions ...". So I want to establish
that HT is a benefit sometimes if it is.
I personally have never seen HT be a benefit. I've seen it be harmless
(most of the time) but never beneficial.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 21:11 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:17 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-21 21:26 ` Bruce Momjian <bruce@momjian.us>
0 siblings, 0 replies; 26+ messages in thread
From: Bruce Momjian @ 2014-08-21 21:26 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; +Cc: pgsql-performance@postgresql.org, Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>; Greg Smith <gregsmithpgsql@gmail.com>
On Thu, Aug 21, 2014 at 02:17:13PM -0700, Josh Berkus wrote:
> >> Actually, I don't know that anyone has posted the benefits of HT. Link?
> >> I want to compare results so that we can figure out what's different
> >> between my case and theirs. Also, it makes a big difference if there is
> >> an advantage to turning HT on for some workloads.
> >
> > I had Greg Smith test my system when it was installed, tested it, and
> > recommended hyper-threading. The system is Debian Squeeze
> > (2.6.32-5-amd64), CPUs are dual Xeon E5620, 8 cores, 16 virtual cores.
>
> Can you post some numerical results?
>
> I'm serious. It's obviously easier for our users if we can blanket
> recommend turning HT off; that's a LOT easier for them than "you might
> want to turn HT off if these conditions ...". So I want to establish
> that HT is a benefit sometimes if it is.
>
> I personally have never seen HT be a benefit. I've seen it be harmless
> (most of the time) but never beneficial.
I know that when hyperthreading was introduced that it was mostly a
negative, but then this was improved, and it might have gotten bad
again. I am afraid results are based on the type of CPU, so I am not
sure we can know a general answer.
I know I asked Greg Smith, and I assume he would know.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ Everyone has their own god. +
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-21 21:26 ` Scott Marlowe <scott.marlowe@gmail.com>
2014-08-21 21:43 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Scott Marlowe <scott.marlowe@gmail.com>
2014-08-21 22:51 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2 siblings, 2 replies; 26+ messages in thread
From: Scott Marlowe @ 2014-08-21 21:26 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; +Cc: Bruce Momjian <bruce@momjian.us>; pgsql-performance; Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On Thu, Aug 21, 2014 at 3:02 PM, Josh Berkus <josh@agliodbs.com> wrote:
> On 08/20/2014 07:40 PM, Bruce Momjian wrote:
>
>> I am also
>> unclear exactly what you tested, as I didn't see it mentioned in the
>> email --- CPU type, CPU count, and operating system would be the minimal
>> information required.
>
> Ooops! I thought I'd posted that earlier, but I didn't.
>
> The processors in question is the Intel(R) Xeon(R) CPU E7- 4850, with 4
> of them for a total of 40 cores or 80 HT cores.
>
> OS is RHEL with 2.6.32-431.3.1.el6.x86_64.
I'm running almost the exact same setup in production as a spare. It
has 4 of those CPUs, 256G RAM, and is currently set to use HT. Since
it's a spare node I might be able to do some testing on it as well.
It's running a 3.2 kernel right now. I could probably get a later
model kernel on it even.
--
To understand recursion, one must first understand recursion.
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 21:26 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Scott Marlowe <scott.marlowe@gmail.com>
@ 2014-08-21 21:43 ` Scott Marlowe <scott.marlowe@gmail.com>
1 sibling, 0 replies; 26+ messages in thread
From: Scott Marlowe @ 2014-08-21 21:43 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; +Cc: Bruce Momjian <bruce@momjian.us>; pgsql-performance; Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On Thu, Aug 21, 2014 at 3:26 PM, Scott Marlowe <scott.marlowe@gmail.com> wrote:
> On Thu, Aug 21, 2014 at 3:02 PM, Josh Berkus <josh@agliodbs.com> wrote:
>> On 08/20/2014 07:40 PM, Bruce Momjian wrote:
>>
>>> I am also
>>> unclear exactly what you tested, as I didn't see it mentioned in the
>>> email --- CPU type, CPU count, and operating system would be the minimal
>>> information required.
>>
>> Ooops! I thought I'd posted that earlier, but I didn't.
>>
>> The processors in question is the Intel(R) Xeon(R) CPU E7- 4850, with 4
>> of them for a total of 40 cores or 80 HT cores.
>>
>> OS is RHEL with 2.6.32-431.3.1.el6.x86_64.
>
> I'm running almost the exact same setup in production as a spare. It
> has 4 of those CPUs, 256G RAM, and is currently set to use HT. Since
> it's a spare node I might be able to do some testing on it as well.
> It's running a 3.2 kernel right now. I could probably get a later
> model kernel on it even.
>
> --
> To understand recursion, one must first understand recursion.
To update this last post, the machine I have is running ubuntu 12.04.1
right now, and I have kernels 3.2, 3.5, 3.8, 3.11, and 3.13 available
to put on it. We're looking at removing it from our current production
cluster so I could likely do all kinds of crazy tests on it.
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 21:26 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Scott Marlowe <scott.marlowe@gmail.com>
@ 2014-08-21 22:51 ` Josh Berkus <josh@agliodbs.com>
2014-08-21 23:08 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Steve Crawford <scrawford@pinpointresearch.com>
1 sibling, 1 reply; 26+ messages in thread
From: Josh Berkus @ 2014-08-21 22:51 UTC (permalink / raw)
To: Scott Marlowe <scott.marlowe@gmail.com>; +Cc: Bruce Momjian <bruce@momjian.us>; pgsql-performance; Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On 08/21/2014 02:26 PM, Scott Marlowe wrote:
> I'm running almost the exact same setup in production as a spare. It
> has 4 of those CPUs, 256G RAM, and is currently set to use HT. Since
> it's a spare node I might be able to do some testing on it as well.
> It's running a 3.2 kernel right now. I could probably get a later
> model kernel on it even.
You know about the IO performance issues with 3.2, yes?
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
--
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 21:26 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Scott Marlowe <scott.marlowe@gmail.com>
2014-08-21 22:51 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-21 23:08 ` Steve Crawford <scrawford@pinpointresearch.com>
2014-08-21 23:29 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
0 siblings, 1 reply; 26+ messages in thread
From: Steve Crawford @ 2014-08-21 23:08 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; Scott Marlowe <scott.marlowe@gmail.com>; +Cc: Bruce Momjian <bruce@momjian.us>; pgsql-performance; Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On 08/21/2014 03:51 PM, Josh Berkus wrote:
> On 08/21/2014 02:26 PM, Scott Marlowe wrote:
>> I'm running almost the exact same setup in production as a spare. It
>> has 4 of those CPUs, 256G RAM, and is currently set to use HT. Since
>> it's a spare node I might be able to do some testing on it as well.
>> It's running a 3.2 kernel right now. I could probably get a later
>> model kernel on it even.
> You know about the IO performance issues with 3.2, yes?
>
Were those 3.2 only and since fixed or are there issues persisting in
3.2+? The 12.04 LTS release of Ubuntu Server was 3.2 but the 14.04 is 3.13.
Cheers,
Steve
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 21:26 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Scott Marlowe <scott.marlowe@gmail.com>
2014-08-21 22:51 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 23:08 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Steve Crawford <scrawford@pinpointresearch.com>
@ 2014-08-21 23:29 ` Josh Berkus <josh@agliodbs.com>
2014-08-21 23:32 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2014-08-22 00:04 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Joshua D. Drake <jd@commandprompt.com>
2014-08-22 06:37 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Scott Marlowe <scott.marlowe@gmail.com>
0 siblings, 3 replies; 26+ messages in thread
From: Josh Berkus @ 2014-08-21 23:29 UTC (permalink / raw)
To: Steve Crawford <scrawford@pinpointresearch.com>; Scott Marlowe <scott.marlowe@gmail.com>; +Cc: Bruce Momjian <bruce@momjian.us>; pgsql-performance; Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On 08/21/2014 04:08 PM, Steve Crawford wrote:
> On 08/21/2014 03:51 PM, Josh Berkus wrote:
>> On 08/21/2014 02:26 PM, Scott Marlowe wrote:
>>> I'm running almost the exact same setup in production as a spare. It
>>> has 4 of those CPUs, 256G RAM, and is currently set to use HT. Since
>>> it's a spare node I might be able to do some testing on it as well.
>>> It's running a 3.2 kernel right now. I could probably get a later
>>> model kernel on it even.
>> You know about the IO performance issues with 3.2, yes?
>>
> Were those 3.2 only and since fixed or are there issues persisting in
> 3.2+? The 12.04 LTS release of Ubuntu Server was 3.2 but the 14.04 is 3.13.
The issues I know of were fixed in 3.9.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 21:26 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Scott Marlowe <scott.marlowe@gmail.com>
2014-08-21 22:51 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 23:08 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Steve Crawford <scrawford@pinpointresearch.com>
2014-08-21 23:29 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-21 23:32 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2 siblings, 0 replies; 26+ messages in thread
From: Mark Kirkwood @ 2014-08-21 23:32 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; Steve Crawford <scrawford@pinpointresearch.com>; Scott Marlowe <scott.marlowe@gmail.com>; +Cc: Bruce Momjian <bruce@momjian.us>; pgsql-performance; Graeme B. Bell <grb@skogoglandskap.no>
On 22/08/14 11:29, Josh Berkus wrote:
> On 08/21/2014 04:08 PM, Steve Crawford wrote:
>> On 08/21/2014 03:51 PM, Josh Berkus wrote:
>>> On 08/21/2014 02:26 PM, Scott Marlowe wrote:
>>>> I'm running almost the exact same setup in production as a spare. It
>>>> has 4 of those CPUs, 256G RAM, and is currently set to use HT. Since
>>>> it's a spare node I might be able to do some testing on it as well.
>>>> It's running a 3.2 kernel right now. I could probably get a later
>>>> model kernel on it even.
>>> You know about the IO performance issues with 3.2, yes?
>>>
>> Were those 3.2 only and since fixed or are there issues persisting in
>> 3.2+? The 12.04 LTS release of Ubuntu Server was 3.2 but the 14.04 is 3.13.
>
> The issues I know of were fixed in 3.9.
>
There is a 3.11 kernel series for Ubuntu 12.04 Precise.
Regards
Mark
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 21:26 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Scott Marlowe <scott.marlowe@gmail.com>
2014-08-21 22:51 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 23:08 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Steve Crawford <scrawford@pinpointresearch.com>
2014-08-21 23:29 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-22 00:04 ` Joshua D. Drake <jd@commandprompt.com>
2 siblings, 0 replies; 26+ messages in thread
From: Joshua D. Drake @ 2014-08-22 00:04 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; Steve Crawford <scrawford@pinpointresearch.com>; Scott Marlowe <scott.marlowe@gmail.com>; +Cc: Bruce Momjian <bruce@momjian.us>; pgsql-performance; Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On 08/21/2014 04:29 PM, Josh Berkus wrote:
>
> On 08/21/2014 04:08 PM, Steve Crawford wrote:
>> On 08/21/2014 03:51 PM, Josh Berkus wrote:
>>> On 08/21/2014 02:26 PM, Scott Marlowe wrote:
>>>> I'm running almost the exact same setup in production as a spare. It
>>>> has 4 of those CPUs, 256G RAM, and is currently set to use HT. Since
>>>> it's a spare node I might be able to do some testing on it as well.
>>>> It's running a 3.2 kernel right now. I could probably get a later
>>>> model kernel on it even.
>>> You know about the IO performance issues with 3.2, yes?
>>>
>> Were those 3.2 only and since fixed or are there issues persisting in
>> 3.2+? The 12.04 LTS release of Ubuntu Server was 3.2 but the 14.04 is 3.13.
>
> The issues I know of were fixed in 3.9.
>
Correct. If you run trusty backports you are good to go.
JD
--
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High Availability, Oracle Conversion, @cmdpromptinc
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 21:26 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Scott Marlowe <scott.marlowe@gmail.com>
2014-08-21 22:51 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 23:08 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Steve Crawford <scrawford@pinpointresearch.com>
2014-08-21 23:29 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-22 06:37 ` Scott Marlowe <scott.marlowe@gmail.com>
2014-08-22 13:01 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Shaun Thomas <sthomas@optionshouse.com>
2 siblings, 1 reply; 26+ messages in thread
From: Scott Marlowe @ 2014-08-22 06:37 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; +Cc: Steve Crawford <scrawford@pinpointresearch.com>; Bruce Momjian <bruce@momjian.us>; pgsql-performance; Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On Thu, Aug 21, 2014 at 5:29 PM, Josh Berkus <josh@agliodbs.com> wrote:
> On 08/21/2014 04:08 PM, Steve Crawford wrote:
>> On 08/21/2014 03:51 PM, Josh Berkus wrote:
>>> On 08/21/2014 02:26 PM, Scott Marlowe wrote:
>>>> I'm running almost the exact same setup in production as a spare. It
>>>> has 4 of those CPUs, 256G RAM, and is currently set to use HT. Since
>>>> it's a spare node I might be able to do some testing on it as well.
>>>> It's running a 3.2 kernel right now. I could probably get a later
>>>> model kernel on it even.
>>> You know about the IO performance issues with 3.2, yes?
>>>
>> Were those 3.2 only and since fixed or are there issues persisting in
>> 3.2+? The 12.04 LTS release of Ubuntu Server was 3.2 but the 14.04 is 3.13.
>
> The issues I know of were fixed in 3.9.
>
I thought they were fixed in 3.8.something? We're running 3.8 on our
production servers but IO is not an issue for us.
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 21:26 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Scott Marlowe <scott.marlowe@gmail.com>
2014-08-21 22:51 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 23:08 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Steve Crawford <scrawford@pinpointresearch.com>
2014-08-21 23:29 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-22 06:37 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Scott Marlowe <scott.marlowe@gmail.com>
@ 2014-08-22 13:01 ` Shaun Thomas <sthomas@optionshouse.com>
0 siblings, 0 replies; 26+ messages in thread
From: Shaun Thomas @ 2014-08-22 13:01 UTC (permalink / raw)
To: Scott Marlowe <scott.marlowe@gmail.com>; Josh Berkus <josh@agliodbs.com>; +Cc: Steve Crawford <scrawford@pinpointresearch.com>; Bruce Momjian <bruce@momjian.us>; pgsql-performance; Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On 08/22/2014 01:37 AM, Scott Marlowe wrote:
> I thought they were fixed in 3.8.something? We're running 3.8 on our
> production servers but IO is not an issue for us.
Yeah. 3.8 fixed a ton of issues that were plaguing us. There were still
a couple patches I wanted that didn't get in until 3.11+, but the worst
of the behavior was solved before that.
Bugs in kernel cache page aging algorithms are bad, m'kay?
--
Shaun Thomas
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312-676-8870
sthomas@optionshouse.com
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-22 14:02 ` Andres Freund <andres@2ndquadrant.com>
2014-08-25 22:13 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2 siblings, 1 reply; 26+ messages in thread
From: Andres Freund @ 2014-08-22 14:02 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; +Cc: Bruce Momjian <bruce@momjian.us>; pgsql-performance@postgresql.org, Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On 2014-08-21 14:02:26 -0700, Josh Berkus wrote:
> On 08/20/2014 07:40 PM, Bruce Momjian wrote:
> > Not sure how you can make such a blanket statement when so many people
> > have tested and shown the benefits of hyper-threading.
>
> Actually, I don't know that anyone has posted the benefits of HT.
> Link?
There's definitely cases where it can help. But it's highly workload
*and* hardware dependent.
> OS is RHEL with 2.6.32-431.3.1.el6.x86_64.
>
> I've emailed a kernel hacker who works at Intel for comment; for one
> thing, I'm wondering if the older kernel version is a problem for a
> system like this.
I'm not sure if it has been backported by redhat, but there
definitely have been significant improvement in SMT aware scheduling
after vanilla 2.6.32.
Greetings,
Andres Freund
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PostgreSQL Development, 24x7 Support, Training & Services
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-22 14:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Andres Freund <andres@2ndquadrant.com>
@ 2014-08-25 22:13 ` Josh Berkus <josh@agliodbs.com>
2014-08-26 02:03 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2014-08-27 04:24 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
0 siblings, 2 replies; 26+ messages in thread
From: Josh Berkus @ 2014-08-25 22:13 UTC (permalink / raw)
To: Andres Freund <andres@2ndquadrant.com>; +Cc: Bruce Momjian <bruce@momjian.us>; pgsql-performance@postgresql.org, Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; Graeme B. Bell <grb@skogoglandskap.no>
On 08/22/2014 07:02 AM, Andres Freund wrote:
> On 2014-08-21 14:02:26 -0700, Josh Berkus wrote:
>> On 08/20/2014 07:40 PM, Bruce Momjian wrote:
>>> Not sure how you can make such a blanket statement when so many people
>>> have tested and shown the benefits of hyper-threading.
>>
>> Actually, I don't know that anyone has posted the benefits of HT.
>> Link?
>
> There's definitely cases where it can help. But it's highly workload
> *and* hardware dependent.
The only cases I've seen where HT can be beneficial is when you have
large numbers of idle connections. Then the idle connections can be
"parked" on the HT virtual cores. However, even in this case I haven't
seen a head-to-head performance comparison.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-22 14:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Andres Freund <andres@2ndquadrant.com>
2014-08-25 22:13 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-26 02:03 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
1 sibling, 0 replies; 26+ messages in thread
From: Mark Kirkwood @ 2014-08-26 02:03 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; Andres Freund <andres@2ndquadrant.com>; +Cc: Bruce Momjian <bruce@momjian.us>; pgsql-performance@postgresql.org, "Graeme B. Bell" <grb@skogoglandskap.no>
On 26/08/14 10:13, Josh Berkus wrote:
> On 08/22/2014 07:02 AM, Andres Freund wrote:
>> On 2014-08-21 14:02:26 -0700, Josh Berkus wrote:
>>> On 08/20/2014 07:40 PM, Bruce Momjian wrote:
>>>> Not sure how you can make such a blanket statement when so many people
>>>> have tested and shown the benefits of hyper-threading.
>>>
>>> Actually, I don't know that anyone has posted the benefits of HT.
>>> Link?
>>
>> There's definitely cases where it can help. But it's highly workload
>> *and* hardware dependent.
>
> The only cases I've seen where HT can be beneficial is when you have
> large numbers of idle connections. Then the idle connections can be
> "parked" on the HT virtual cores. However, even in this case I haven't
> seen a head-to-head performance comparison.
>
I recall HT beneficial on a single socket (i3 or i7), using pgbench as
the measuring tool. However I didn't save the results at the time. I've
just got some new ssd's to play with so might run some pgbench tests on
my home machine (Haswell i7) with HT on and off.
Regards
Mark
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^ permalink raw reply [nested|flat] 26+ messages in thread
* Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-21 02:40 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Bruce Momjian <bruce@momjian.us>
2014-08-21 21:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-22 14:02 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Andres Freund <andres@2ndquadrant.com>
2014-08-25 22:13 ` Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
@ 2014-08-27 04:24 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
1 sibling, 0 replies; 26+ messages in thread
From: Mark Kirkwood @ 2014-08-27 04:24 UTC (permalink / raw)
To: Josh Berkus <josh@agliodbs.com>; Andres Freund <andres@2ndquadrant.com>; +Cc: Bruce Momjian <bruce@momjian.us>; pgsql-performance@postgresql.org, "Graeme B. Bell" <grb@skogoglandskap.no>
On 26/08/14 10:13, Josh Berkus wrote:
> On 08/22/2014 07:02 AM, Andres Freund wrote:
>> On 2014-08-21 14:02:26 -0700, Josh Berkus wrote:
>>> On 08/20/2014 07:40 PM, Bruce Momjian wrote:
>>>> Not sure how you can make such a blanket statement when so many people
>>>> have tested and shown the benefits of hyper-threading.
>>>
>>> Actually, I don't know that anyone has posted the benefits of HT.
>>> Link?
>>
>> There's definitely cases where it can help. But it's highly workload
>> *and* hardware dependent.
>
> The only cases I've seen where HT can be beneficial is when you have
> large numbers of idle connections. Then the idle connections can be
> "parked" on the HT virtual cores. However, even in this case I haven't
> seen a head-to-head performance comparison.
>
I've just had a pair of Crucial m550's arrive, so a bit of benchmarking
is in order. The results (below) seem to suggest that HT enabled is
certainly not inhibiting scaling performance for single socket i7's. I
performed several runs (typical results shown below).
Intel i7-4770 3.4 Ghz, 16G
2x Crucial m550
Ubuntu 14.04
Postgres 9.4 beta2
logging_collector = on
max_connections = 600
shared_buffers = 1GB
wal_buffers = 32MB
checkpoint_segments = 128
effective_cache_size = 10GB
pgbench scale = 300
test duration (each) = 600s
db on 1x m550
xlog on 1x m550
clients | tps (HT)| tps (no HT)
--------+----------+-------------
4 | 517 | 520
8 | 1013 | 999
16 | 1938 | 1913
32 | 3574 | 3560
64 | 5873 | 5412
128 | 8351 | 7450
256 | 9426 | 7840
512 | 9357 | 7288
Regards
Mark
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^ permalink raw reply [nested|flat] 26+ messages in thread
end of thread, other threads:[~2014-08-27 04:24 UTC | newest]
Thread overview: 26+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2014-08-20 19:13 Re: Turn off Hyperthreading! WAS: 60 core performance with 9.3 Josh Berkus <josh@agliodbs.com>
2014-08-20 20:36 ` Shaun Thomas <sthomas@optionshouse.com>
2014-08-20 23:59 ` Peter Geoghegan <peter.geoghegan86@gmail.com>
2014-08-20 23:14 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2014-08-21 10:02 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2014-08-21 14:14 ` Shaun Thomas <sthomas@optionshouse.com>
2014-08-21 02:40 ` Bruce Momjian <bruce@momjian.us>
2014-08-21 02:47 ` Tatsuo Ishii <ishii@postgresql.org>
2014-08-21 20:03 ` Graeme B. Bell <grb@skogoglandskap.no>
2014-08-21 21:02 ` Josh Berkus <josh@agliodbs.com>
2014-08-21 21:11 ` Bruce Momjian <bruce@momjian.us>
2014-08-21 21:17 ` Josh Berkus <josh@agliodbs.com>
2014-08-21 21:26 ` Bruce Momjian <bruce@momjian.us>
2014-08-21 21:26 ` Scott Marlowe <scott.marlowe@gmail.com>
2014-08-21 21:43 ` Scott Marlowe <scott.marlowe@gmail.com>
2014-08-21 22:51 ` Josh Berkus <josh@agliodbs.com>
2014-08-21 23:08 ` Steve Crawford <scrawford@pinpointresearch.com>
2014-08-21 23:29 ` Josh Berkus <josh@agliodbs.com>
2014-08-21 23:32 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2014-08-22 00:04 ` Joshua D. Drake <jd@commandprompt.com>
2014-08-22 06:37 ` Scott Marlowe <scott.marlowe@gmail.com>
2014-08-22 13:01 ` Shaun Thomas <sthomas@optionshouse.com>
2014-08-22 14:02 ` Andres Freund <andres@2ndquadrant.com>
2014-08-25 22:13 ` Josh Berkus <josh@agliodbs.com>
2014-08-26 02:03 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2014-08-27 04:24 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
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