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* hyperthreadin low performance
@ 2015-07-21 02:59 Jeison Bedoya Delgado <jeisonb@audifarma.com.co>
2015-07-21 08:04 ` Re: hyperthreadin low performance David Rowley <david.rowley@2ndquadrant.com>
0 siblings, 1 reply; 5+ messages in thread
From: Jeison Bedoya Delgado @ 2015-07-21 02:59 UTC (permalink / raw)
To: pgsql-performance
hi everyone,
Recently update a database to machine with RHEL7, but i see that the
performance is betther if the hyperthreading tecnology is deactivated
and use only 32 cores.
is normal that the machine performance is better with 32 cores that 64
cores?.
BD: postgresql 9.3.5
Machine: Dell PE R820
processor: 4x Intel(R) Xeon(R) CPU E5-4620 v2 @ 2.60GHz eigth-core
RAM: 128GB
Storage SSD SAN
thanks by your help
--
Atentamente,
JEISON BEDOYA DELGADO
ADM.Servidores y comunicaciones
AUDIFARMA S.A.
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^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: hyperthreadin low performance
2015-07-21 02:59 hyperthreadin low performance Jeison Bedoya Delgado <jeisonb@audifarma.com.co>
@ 2015-07-21 08:04 ` David Rowley <david.rowley@2ndquadrant.com>
2015-07-21 09:07 ` Re: hyperthreadin low performance Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
0 siblings, 1 reply; 5+ messages in thread
From: David Rowley @ 2015-07-21 08:04 UTC (permalink / raw)
To: Jeison Bedoya Delgado <jeisonb@audifarma.com.co>; +Cc: pgsql-performance
On 21 July 2015 at 14:59, Jeison Bedoya Delgado <jeisonb@audifarma.com.co>
wrote:
> hi everyone,
>
> Recently update a database to machine with RHEL7, but i see that the
> performance is betther if the hyperthreading tecnology is deactivated and
> use only 32 cores.
>
> is normal that the machine performance is better with 32 cores that 64
> cores?.
>
>
You might be interested in
http://www.postgresql.org/message-id/53F4F36E.6050003@agliodbs.com
Regards
David Rowley
--
David Rowley http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/;
PostgreSQL Development, 24x7 Support, Training & Services
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: hyperthreadin low performance
2015-07-21 02:59 hyperthreadin low performance Jeison Bedoya Delgado <jeisonb@audifarma.com.co>
2015-07-21 08:04 ` Re: hyperthreadin low performance David Rowley <david.rowley@2ndquadrant.com>
@ 2015-07-21 09:07 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2015-07-23 11:37 ` Re: hyperthreadin low performance domenico febbo <mimmopasticcio@gmail.com>
0 siblings, 1 reply; 5+ messages in thread
From: Mark Kirkwood @ 2015-07-21 09:07 UTC (permalink / raw)
To: David Rowley <david.rowley@2ndquadrant.com>; Jeison Bedoya Delgado <jeisonb@audifarma.com.co>; +Cc: pgsql-performance
On 21/07/15 20:04, David Rowley wrote:
> On 21 July 2015 at 14:59, Jeison Bedoya Delgado
> <jeisonb@audifarma.com.co <mailto:jeisonb@audifarma.com.co>> wrote:
>
> hi everyone,
>
> Recently update a database to machine with RHEL7, but i see that the
> performance is betther if the hyperthreading tecnology is
> deactivated and use only 32 cores.
>
> is normal that the machine performance is better with 32 cores that
> 64 cores?.
>
>
> You might be interested in
> http://www.postgresql.org/message-id/53F4F36E.6050003@agliodbs.com
>
However I do wonder if we have been misinterpreting these tests. We tend
to assume the position of "see hyperthreading is bad, switch it off".
The linked post under the one above:
http://www.postgresql.org/message-id/53ED371D.109@catalyst.net.nz
shows that 60 core (no hyperthreading) performance is also pessimal,
leading me to conclude that *perhaps* it is simply the number of cores
that is the problem - particularly as benchmark results for single
socket cpus clearly show hyperthreading helps performance...
Regards
Mark
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^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: hyperthreadin low performance
2015-07-21 02:59 hyperthreadin low performance Jeison Bedoya Delgado <jeisonb@audifarma.com.co>
2015-07-21 08:04 ` Re: hyperthreadin low performance David Rowley <david.rowley@2ndquadrant.com>
2015-07-21 09:07 ` Re: hyperthreadin low performance Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
@ 2015-07-23 11:37 ` domenico febbo <mimmopasticcio@gmail.com>
2015-07-25 04:10 ` Re: hyperthreadin low performance Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
0 siblings, 1 reply; 5+ messages in thread
From: domenico febbo @ 2015-07-23 11:37 UTC (permalink / raw)
To: Mark Kirkwood <mark.kirkwood@catalyst.net.nz>; +Cc: David Rowley <david.rowley@2ndquadrant.com>; Jeison Bedoya Delgado <jeisonb@audifarma.com.co>; pgsql-performance
is the problem also in PostgreSQL 9.4.x?
I'm going to buy a production's server with 4 sockets E7-4850 12 cores
so 12*4 = 48 cores (and 96 threads using HT).
What do you suggest?
Using or not HT?
BR
Domenico
2015-07-21 11:07 GMT+02:00 Mark Kirkwood <mark.kirkwood@catalyst.net.nz>:
> On 21/07/15 20:04, David Rowley wrote:
>>
>> On 21 July 2015 at 14:59, Jeison Bedoya Delgado
>> <jeisonb@audifarma.com.co <mailto:jeisonb@audifarma.com.co>> wrote:
>>
>> hi everyone,
>>
>> Recently update a database to machine with RHEL7, but i see that the
>> performance is betther if the hyperthreading tecnology is
>> deactivated and use only 32 cores.
>>
>> is normal that the machine performance is better with 32 cores that
>> 64 cores?.
>>
>>
>> You might be interested in
>> http://www.postgresql.org/message-id/53F4F36E.6050003@agliodbs.com
>>
>
> However I do wonder if we have been misinterpreting these tests. We tend to
> assume the position of "see hyperthreading is bad, switch it off".
>
> The linked post under the one above:
>
> http://www.postgresql.org/message-id/53ED371D.109@catalyst.net.nz
>
> shows that 60 core (no hyperthreading) performance is also pessimal, leading
> me to conclude that *perhaps* it is simply the number of cores that is the
> problem - particularly as benchmark results for single socket cpus clearly
> show hyperthreading helps performance...
>
> Regards
>
> Mark
>
>
> --
> Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org)
>
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-performance
--
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^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: hyperthreadin low performance
2015-07-21 02:59 hyperthreadin low performance Jeison Bedoya Delgado <jeisonb@audifarma.com.co>
2015-07-21 08:04 ` Re: hyperthreadin low performance David Rowley <david.rowley@2ndquadrant.com>
2015-07-21 09:07 ` Re: hyperthreadin low performance Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2015-07-23 11:37 ` Re: hyperthreadin low performance domenico febbo <mimmopasticcio@gmail.com>
@ 2015-07-25 04:10 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
0 siblings, 0 replies; 5+ messages in thread
From: Mark Kirkwood @ 2015-07-25 04:10 UTC (permalink / raw)
To: domenico febbo <mimmopasticcio@gmail.com>; +Cc: David Rowley <david.rowley@2ndquadrant.com>; Jeison Bedoya Delgado <jeisonb@audifarma.com.co>; pgsql-performance
On 23/07/15 23:37, domenico febbo wrote:
> is the problem also in PostgreSQL 9.4.x?
> I'm going to buy a production's server with 4 sockets E7-4850 12 cores
> so 12*4 = 48 cores (and 96 threads using HT).
>
> What do you suggest?
> Using or not HT?
>
From my experience 9.4 is considerably better (we are using it on the
60 core box mentioned prev).
48 cores should be fine, enabling HT and asking Postgres to effectively
handle 96 could provoke issues. However it is reasonably easy to test -
tune shared_buffers and checkpoint segments sensibly and run pgbench for
a steadily increasing number of clients. With 48 cores you should
(hopefully) see a tps curve that increases and then gently flattens off
somewhere. If 96 cores are "too many" then you will see a tps curve that
initially increases then sharply drops.
Cheers
Mark
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2015-07-21 02:59 hyperthreadin low performance Jeison Bedoya Delgado <jeisonb@audifarma.com.co>
2015-07-21 08:04 ` David Rowley <david.rowley@2ndquadrant.com>
2015-07-21 09:07 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
2015-07-23 11:37 ` domenico febbo <mimmopasticcio@gmail.com>
2015-07-25 04:10 ` Mark Kirkwood <mark.kirkwood@catalyst.net.nz>
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