Re: 8.3.9 - latency spikes with Linux (and tuning for consistently low latency)

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)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