Date: Fri, 9 Oct 2015 13:01:53 +0000 (UTC)
From: Kevin Grittner <kgrittn@ymail.com>
Reply-To: Kevin Grittner <kgrittn@ymail.com>
To: ajaykbs <ajayakumarbs@gmail.com>,
 "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Message-ID: <24941167.1086518.1444395713314.JavaMail.yahoo@mail.yahoo.com>
In-Reply-To: <1443864850869-5868480.post@n5.nabble.com>
References: <1443864850869-5868480.post@n5.nabble.com>
Subject: Re: Re: Multi processor server overloads occationally
 with system process while running postgresql-9.4
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On Saturday, October 3, 2015 4:36 AM, ajaykbs <ajayakumarbs@gmail.com> wrote:

> version: Postgresql-9.4
> Hardware: HP DL980 (8-processor, 80 cores w/o hyper threading, 512GB RAM)
> Operating system: Red Hat Enterprise Linux Server release 6.4 (Santiago)
> uname -a : Linux host1 2.6.32-358.el6.x86_64 #1 SMP Tue Jan 29 11:47:41 EST
> 2013 x86_64 x86_64 x86_64 GNU/Linux Single database with separate tablespace
> for main-data, pg_xlog and indexes
>
> I have a database having 770GB size and expected to grow to 2TB within the
> next year. The database was running in a 2processor HP DL560 (16 cores) and
> as the transactions of the database were found increasing, we have changed
> the hardware to DL980 with 8 processors and 512GB RAM.
>
> Problem It is observed that at some times during moderate load the CPU
> usage goes up to 400% and the users are not able to complete the queries in
> expected time. But the load is contributed by some system process only. The
> average connections are normally 50. But when this happens the connections
> will shoot up to max-connections.

You might find this thread interesting:

http://www.postgresql.org/message-id/flat/55783940.8080302@wi3ck.info#55783940.8080302@wi3ck.info

The short version is that in existing production versions you can
easily run in to such symptoms when you get to 8 or more CPU
packages.  The problem seems to be solved in the development
versions of 9.5 (with changes not suitable for back-patching to a
stable branch).

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company


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