From: Kevin Grittner <Kevin.Grittner@wicourts.gov>
To: Marinos Yannikos <mjy@geizhals.at>
Cc: pgsql-performance <pgsql-performance@postgresql.org>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: 8.3.9 - latency spikes with Linux (and tuning for consistently low latency)
Date: Thu, 15 Apr 2010 12:47:26 -0500
Message-ID: <4BC70ADE0200002500030965@gw.wicourts.gov> (raw)
In-Reply-To: <4674.1271353080@sss.pgh.pa.us>
References: <4BC742C8.2050301@geizhals.at>
<4BC742C8.2050301@geizhals.at>
<4674.1271353080@sss.pgh.pa.us>
Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Have you checked whether the spikes correlate with checkpoints?
> Turn on log_checkpoints and watch for awhile. If so, fooling with
> the checkpoint parameters might give some relief.
If that by itself doesn't do it, I've found that making the
background writer more aggressive can help. We've had good luck
with:
bgwriter_lru_maxpages = 1000
bgwriter_lru_multiplier = 4.0
If you still have checkpoint-related latency issues, you could try
scaling back shared_buffers, letting the OS cache handle more of the
data.
Also, if you have a RAID controller with a battery-backed RAM cache,
make sure it is configured for write-back.
-Kevin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: Kevin.Grittner@wicourts.gov, mjy@geizhals.at, tgl@sss.pgh.pa.us
Subject: Re: 8.3.9 - latency spikes with Linux (and tuning for consistently low latency)
In-Reply-To: <4BC70ADE0200002500030965@gw.wicourts.gov>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox