Re: Massive I/O spikes during checkpoint - Mailing list pgsql-performance

From Jeff Janes
Subject Re: Massive I/O spikes during checkpoint
Date
Msg-id CAMkU=1zq2DDFnnoqK_TnFgzz7WF5SSTjvAVU7ga2Ljbpu_yECQ@mail.gmail.com
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In response to Re: Massive I/O spikes during checkpoint  (Andres Freund <andres@2ndquadrant.com>)
Responses Re: Massive I/O spikes during checkpoint
List pgsql-performance
On Tue, Jul 10, 2012 at 5:44 AM, Andres Freund <andres@2ndquadrant.com> wrote:
> On Tuesday, July 10, 2012 08:14:00 AM Maxim Boguk wrote:
>>
>> So kernel doesn't start write any pages out in background before it has at
>> least 13Gb dirty pages in kernel memory.
>> And at end of the checkpoint kernel trying flush all dirty pages to disk.

> Thast not entirely true. The kernel will also writeout pages which haven't
> been written to for dirty_expire_centisecs.

There seems to be many situations in which it totally fails to do that.

Although I've never been able to categorize just what those situations are.

Cheers,

Jeff

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