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* shared_buffers on ubuntu precise
@ 2012-11-30 19:57 Ben Chobot <bench@silentmedia.com>
0 siblings, 1 reply; 6+ messages in thread
From: Ben Chobot @ 2012-11-30 19:57 UTC (permalink / raw)
To: sthomas@optionshouse.com; +Cc: pgsql-performance
On Nov 30, 2012, at 8:06 AM, Shaun Thomas wrote:
> I say that because you mentioned you're using Ubuntu 12.04, and we were
> having some problems with PG on that platform. With shared_buffers over
> 4GB, it starts doing really weird things to the memory subsystem.
> Whatever it does causes the kernel to purge cache rather aggressively.
> We saw a 60% reduction in read IO by reducing shared_buffers to 4GB.
> Without as many reads, your writes should be much less disruptive.
Hm, this sounds like something we should look into. Before we start digging do you have more to share, or did you leave it with the "huh, that's weird; this seems to fix it" solution?=
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: shared_buffers on ubuntu precise
@ 2012-11-30 20:01 Shaun Thomas <sthomas@optionshouse.com>
parent: Ben Chobot <bench@silentmedia.com>
0 siblings, 1 reply; 6+ messages in thread
From: Shaun Thomas @ 2012-11-30 20:01 UTC (permalink / raw)
To: Ben Chobot <bench@silentmedia.com>; +Cc: pgsql-performance
On 11/30/2012 01:57 PM, Ben Chobot wrote:
> Hm, this sounds like something we should look into. Before we start
> digging do you have more to share, or did you leave it with the "huh,
> that's weird; this seems to fix it" solution?
We're still testing. We're still on the -31 kernel. We tried the -33
kernel which *might* fix it, but then this happened:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1084264
So now we're testing -34 which is currently proposed. Either way, it's
pretty clear that Ubuntu's choice of patches to backport is rather
eclectic and a little wonky, or that nailing down load calculations went
awry since the NOHZ stuff started, or both. At this point, I wish we'd
stayed on CentOS.
--
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 500 | Chicago IL, 60604
312-444-8534
sthomas@optionshouse.com
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^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: shared_buffers on ubuntu precise
@ 2012-11-30 20:38 Bruce Momjian <bruce@momjian.us>
parent: Shaun Thomas <sthomas@optionshouse.com>
0 siblings, 2 replies; 6+ messages in thread
From: Bruce Momjian @ 2012-11-30 20:38 UTC (permalink / raw)
To: Shaun Thomas <sthomas@optionshouse.com>; +Cc: Ben Chobot <bench@silentmedia.com>; pgsql-performance
On Fri, Nov 30, 2012 at 02:01:45PM -0600, Shaun Thomas wrote:
> On 11/30/2012 01:57 PM, Ben Chobot wrote:
>
> >Hm, this sounds like something we should look into. Before we start
> >digging do you have more to share, or did you leave it with the "huh,
> >that's weird; this seems to fix it" solution?
>
> We're still testing. We're still on the -31 kernel. We tried the -33
> kernel which *might* fix it, but then this happened:
>
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1084264
>
> So now we're testing -34 which is currently proposed. Either way,
> it's pretty clear that Ubuntu's choice of patches to backport is
> rather eclectic and a little wonky, or that nailing down load
> calculations went awry since the NOHZ stuff started, or both. At
> this point, I wish we'd stayed on CentOS.
Or Debian. Not sure what would justify use of Ubuntu as a server,
except wanting to have the exact same OS as their personal computers.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
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^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: shared_buffers on ubuntu precise
@ 2012-11-30 20:46 Shaun Thomas <sthomas@optionshouse.com>
parent: Bruce Momjian <bruce@momjian.us>
1 sibling, 0 replies; 6+ messages in thread
From: Shaun Thomas @ 2012-11-30 20:46 UTC (permalink / raw)
To: Bruce Momjian <bruce@momjian.us>; +Cc: Ben Chobot <bench@silentmedia.com>; pgsql-performance
On 11/30/2012 02:38 PM, Bruce Momjian wrote:
> Or Debian. Not sure what would justify use of Ubuntu as a server,
> except wanting to have the exact same OS as their personal computers.
Honestly not sure why we went that direction. I'm not in the sysadmin
group, though I do work with them pretty closely. I think it was because
of the LTS label, and the fact that the packages are quite a bit more
recent than Debian stable.
I can say however, that I'm testing the 3.4 kernel right now, and it
seems much better. I may be able to convince them to install that
instead if their own tests prove beneficial.
--
Shaun Thomas
OptionsHouse | 141 W. Jackson Blvd. | Suite 500 | Chicago IL, 60604
312-444-8534
sthomas@optionshouse.com
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^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: shared_buffers on ubuntu precise
@ 2012-11-30 22:21 Daniel Farina <daniel@heroku.com>
parent: Bruce Momjian <bruce@momjian.us>
1 sibling, 1 reply; 6+ messages in thread
From: Daniel Farina @ 2012-11-30 22:21 UTC (permalink / raw)
To: Bruce Momjian <bruce@momjian.us>; +Cc: Shaun Thomas <sthomas@optionshouse.com>; Ben Chobot <bench@silentmedia.com>; pgsql-performance
On Fri, Nov 30, 2012 at 12:38 PM, Bruce Momjian <bruce@momjian.us> wrote:
> Or Debian. Not sure what would justify use of Ubuntu as a server,
> except wanting to have the exact same OS as their personal computers.
We have switched from Debian to Ubuntu: there is definitely non-zero
value in the PPA hosting (although it's rather terrible in many ways),
regular LTS releases (even if you choose not to use them right away,
and know they are somewhat buggy at times), and working with AWS and
Canonical as organizations (that, most importantly, can interact
directly without my own organization) on certain issues. For example,
this dog of a bug:
https://bugs.launchpad.net/ubuntu/+source/linux-ec2/+bug/929941
I also frequently take advantage of Debian unstable for backporting of
specific packages that are very important to me, so there's a lot of
value to me in Ubuntu being quite similar to Debian. In fact, even
though I say we 'switched', it's not as though we re-did some
entrenched systems from Debian to Ubuntu -- rather, we employ both
systems at the same time and I don't recall gnashing of teeth about
that, because they are very similar. Yet, there is a clear Ubuntu
preference for new systems made today and, to wit, I can't think of
anyone with more than the most mild preference for Debian. Conversely,
I'd say the preference for Ubuntu for the aforementioned reasons is
clear but moderate at most.
Also, there's the similarity to the lap/desktop environment. Often
cited with some derision, yet it does add a lot of value, even if
people run slightly newer Ubuntus on their non-production computer.
--
fdr
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^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: shared_buffers on ubuntu precise
@ 2012-11-30 22:36 Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
parent: Daniel Farina <daniel@heroku.com>
0 siblings, 0 replies; 6+ messages in thread
From: Mark Kirkwood @ 2012-11-30 22:36 UTC (permalink / raw)
To: Daniel Farina <daniel@heroku.com>; +Cc: Bruce Momjian <bruce@momjian.us>; Shaun Thomas <sthomas@optionshouse.com>; Ben Chobot <bench@silentmedia.com>; pgsql-performance
On 01/12/12 11:21, Daniel Farina wrote:
> On Fri, Nov 30, 2012 at 12:38 PM, Bruce Momjian <bruce@momjian.us> wrote:
>> Or Debian. Not sure what would justify use of Ubuntu as a server,
>> except wanting to have the exact same OS as their personal computers.
>
> We have switched from Debian to Ubuntu: there is definitely non-zero
> value in the PPA hosting (although it's rather terrible in many ways),
> regular LTS releases (even if you choose not to use them right away,
> and know they are somewhat buggy at times), and working with AWS and
> Canonical as organizations (that, most importantly, can interact
> directly without my own organization) on certain issues. For example,
> this dog of a bug:
>
> https://bugs.launchpad.net/ubuntu/+source/linux-ec2/+bug/929941
>
> I also frequently take advantage of Debian unstable for backporting of
> specific packages that are very important to me, so there's a lot of
> value to me in Ubuntu being quite similar to Debian. In fact, even
> though I say we 'switched', it's not as though we re-did some
> entrenched systems from Debian to Ubuntu -- rather, we employ both
> systems at the same time and I don't recall gnashing of teeth about
> that, because they are very similar. Yet, there is a clear Ubuntu
> preference for new systems made today and, to wit, I can't think of
> anyone with more than the most mild preference for Debian. Conversely,
> I'd say the preference for Ubuntu for the aforementioned reasons is
> clear but moderate at most.
>
> Also, there's the similarity to the lap/desktop environment. Often
> cited with some derision, yet it does add a lot of value, even if
> people run slightly newer Ubuntus on their non-production computer.
>
+1
We have gone through pretty much the same process in the last couple of
years. Most of our new systems run Ubuntu, some Debian.
There is definitely value in running the "same" system on the desktop
too - often makes bug replication ridiculously easy (no having to find
the appropriate test environment, ask if I can hammer/punish/modify it
etc etc, and no need even spin up a VM).
Cheers
Mark
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^ permalink raw reply [nested|flat] 6+ messages in thread
end of thread, other threads:[~2012-11-30 22:36 UTC | newest]
Thread overview: 6+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2012-11-30 19:57 shared_buffers on ubuntu precise Ben Chobot <bench@silentmedia.com>
2012-11-30 20:01 ` Shaun Thomas <sthomas@optionshouse.com>
2012-11-30 20:38 ` Bruce Momjian <bruce@momjian.us>
2012-11-30 20:46 ` Shaun Thomas <sthomas@optionshouse.com>
2012-11-30 22:21 ` Daniel Farina <daniel@heroku.com>
2012-11-30 22:36 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
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