Re: Just-in-time Background Writer Patch+Test Results

Greg Smith <gsmith(at)gregsmith(dot)com> writes:
> On Sat, 8 Sep 2007, Tom Lane wrote:
>> In fact, given the numbers you show here, I'd say you should leave the
>> default cycle time at 200ms. The 10ms value is eating way more CPU and
>> producing absolutely no measured benefit relative to 200ms...

> My server is a bit underpowered to run at 10ms and gain anything when
> doing a stress test like this; I was content that it didn't degrade
> performance significantly, that was the best I could hope for. I would
> expect the class of systems that Simon and Heikki are working with could
> show significant benefit from running the BGW that often.

Quite possibly. So it sounds like we still need to expose
bgwriter_delay as a tunable.

It might be interesting to consider making the delay auto-tune: if you
wake up and find nothing (much) to do, sleep longer the next time,
conversely shorten the delay when work picks up. Something for 8.4,
though, at this point.

regards, tom lane