| From: | Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz> |
|---|---|
| To: | Josh Berkus <josh(at)agliodbs(dot)com> |
| Cc: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>, postgres performance list <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: High CPU usage / load average after upgrading to Ubuntu 12.04 |
| Date: | 2013-02-19 04:28:00 |
| Message-ID: | 5122FF50.8030903@catalyst.net.nz |
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| Lists: | pgsql-performance |
On 19/02/13 13:39, Josh Berkus wrote:
> Scott,
>
>> So do you have generally slow IO, or is it fsync behavior etc?
> All tests except pgBench show this system as superfast. Bonnie++ and DD
> tests are good (200 to 300mb/s), and test_fsync shows 14K/second.
> Basically it has no issues until checkpoint kicks in, at which time the
> entire system basically halts for the duration of the checkpoint.
>
> For that matter, if I run a pgbench and halt it just before checkpoint
> kicks in, I get around 12000TPS, which is what I'd expect on this system.
>
> At this point, we've tried 3.2.0.26, 3.2.0.27, 3.4.0, and tried updating
> the RAID driver, and changing the IO scheduler. Nothing seems to affect
> the behavior. Testing using Ext4 (instead of XFS) next.
>
>
Might be worth looking at your vm.dirty_ratio, vm.dirty_background_ratio
and friends settings. We managed to choke up a system with 16x SSD by
leaving them at their defaults...
Cheers
Mark
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