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Re: bgwriter, checkpoints, curious (seeing delays)

From: Tory M Blue <tmblue(at)gmail(dot)com>
To: Devrim GÜNDÜZ <devrim(at)gunduz(dot)org>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: bgwriter, checkpoints, curious (seeing delays)
Date: 2010-02-26 19:01:55
Message-ID: 8a547c841002261101l6bf9bd37j8b2068a0190bedff@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
2010/2/25 Devrim GÜNDÜZ <devrim(at)gunduz(dot)org>:
> On Thu, 2010-02-25 at 23:01 -0800, Tory M Blue wrote:
>
>> Checkpoint_timeout is the default and that looks like 5 mins (300
>> seconds). And is obviously why I have such a discrepancy between time
>> reached and requested.
>
> If you have a high load, you may want to start tuning with 15 minutes,
> and bump it to 30 mins if needed. Also you may want to decrease segments
> value based on your findings, since increasing only one of them won't
> help you a lot.
>
> As I wrote before, pg_stat_bgwriter is your friend here.

Actually these servers have almost no load. Really they run very cool

Load Average (for the day):
Cur: 0.16 Load
Avg: 0.22 Load

So I don't think it's load  No network issues (that I've found)  and
while the server will eventually eat all the memory it's currently
sitting with 4 gb free.

Mem Total (for the day):
Cur: 25.55 GBytes
Avg: 25.55 GBytes
Max: 25.55 GBytes
	Mem Available (for the day):
Cur: 4.72 GBytes
Avg: 5.15 GBytes
Max: 5.71 GBytes
	Bytes Used (for the day):
Cur: 20.83 GBytes
Avg: 20.40 GBytes
Max: 21.20 GBytes


Thanks for your pointers, I'm continuing to look and will do some
tests today. I also hear you about fsync and will do some testing here
to see why this was set (been running for 4-6 years), and that setting
was probably set way way back in the day and it's survived each
upgrade/hardware/storage update.

Tory

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Subject: Re: bgwriter, checkpoints, curious (seeing delays)
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