Subject: Re: High CPU Load
From: =?ISO-8859-1?Q?J=E9r=F4me?= BENOIS <benois@argia-engineering.fr>
To: pgsql-performance@postgresql.org
Cc: infra@sharengo.org
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Date: Tue, 03 Oct 2006 09:36:22 +0200
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Hi All,

	I reply to me, we solved a CPU Load problem. We had an external batch
who used an expensive SQL view and took 99% of the CPU.

	Thanks all for you help !

                    -------------------

	I started the HAPlatform open-source project is a part of Share'nGo
Project, this goal is define all documentation and scripts required to
install and maintain High Available platform.

Tow platform are targeted :

        * LAPJ : Linux Apache PostgreSQL Java

        * LAMP : Linux Apache MySQL PHP

	The first documentation is here (it's my postgres configuration) :

http://sharengo.org/haplatform/docs/PostgreSQL/en/html_single/index.html


Cheers,
J=C3=A9r=C3=B4me.
--=20
Open-Source : http://www.sharengo.org
Corporate : http://www.argia-engineering.fr

Le vendredi 22 septembre 2006 =C3=A0 09:43 +0200, J=C3=A9r=C3=B4me BENOIS a=
 =C3=A9crit :
> Hi, Markus,
>=20
> Le mardi 19 septembre 2006 =C3=A0 15:09 +0200, Markus Schaber a =C3=A9cri=
t :
> > Hi, Jerome,
> >=20
> > J=C3=A9r=C3=B4me BENOIS wrote:
> >=20
> > >>> Now i Have 335 concurrent connections, i decreased work_mem paramet=
er to
> > >>> 32768 and disabled Hyper Threading in BIOS. But my CPU load is stil=
l
> > >>> very important.
> > >> What are your settings for commit_siblings and commit_delay?
> > > It default :
> > >=20
> > > #commit_delay =3D 01   # range 0-100000, inmicroseconds
> > > #commit_siblings =3D 5 # range 1-1000
> >=20
> > You should uncomment them, and play with different settings. I'd try a
> > commit_delay of 100, and commit_siblings of 5 to start with.
> >=20
> > > I plan to return to previous version : 7.4.6 in and i will reinstall =
all
> > > in a dedicated server in order to reproduce and solve the problem.
> >=20
> > You should use at least 7.4.13 as it fixes some critical buts that were
> > in 7.4.6. They use the same on-disk format and query planner logic, so
> > they should not have any difference.
> >=20
> > I don't have much more ideas what the problem could be.
> >=20
> > Can you try to do some profiling (e. G. with statement logging) to see
> > what specific statements are the one that cause high cpu load?
> >=20
> > Are there other differences (besides the PostgreSQL version) between th=
e
> > two installations? (Kernel, libraries, other software...)
> nothing.
>=20
> I returned to the previous version 7.4.6 in my production server, it's
> work fine !
>=20
> And I plan to reproduce this problem in a dedicated server, and i will
> send all informations in this list in the next week.
>=20
> I hope your help for solve this problem.
>=20
> Cheers,
> J=C3=A9r=C3=B4me.
>=20
> > HTH,
> > Markus


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