From: | David Kerr <dmk(at)mr-paradox(dot)net> |
---|---|
To: | Maxim Boguk <maxim(dot)boguk(at)gmail(dot)com> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Massive I/O spikes during checkpoint |
Date: | 2012-07-10 06:03:23 |
Message-ID: | 07928283-528B-4499-BEC2-7E9098D6D734@mr-paradox.net |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
On Jul 9, 2012, at 10:51 PM, Maxim Boguk wrote:
>
>
> But what appears to be happening is that all of the data is being written out at the end of the checkpoint.
>
> This happens at every checkpoint while the system is under load.
>
> I get the feeling that this isn't the correct behavior and i've done something wrong.
>
>
>
> It's not an actual checkpoints.
> It's is a fsync after checkpoint which create write spikes hurting server.
> You should set sysctl vm.dirty_background_bytes and vm.dirty_bytes to reasonable low values
So use bla_bytes instead of bla_ratio?
> (for 512MB raid controller with cache I would suggest to sometning like
> vm.dirty_background_bytes = 33554432
> vm.dirty_bytes = 268435456
> 32MB and 256MB respectively)
I'll take a look.
>
> If youre server doesn't have raid with BBU cache - then you should tune these values to much lower values.
>
> Please read http://blog.2ndquadrant.com/tuning_linux_for_low_postgresq/
> and related posts.
yeah, I saw that I guess I didn't put 2+2 together. thanks.
From | Date | Subject | |
---|---|---|---|
Next Message | Maxim Boguk | 2012-07-10 06:14:00 | Re: Massive I/O spikes during checkpoint |
Previous Message | David Kerr | 2012-07-10 05:59:04 | Re: Massive I/O spikes during checkpoint |