Re: Time to up bgwriter_lru_maxpages?

On Wed, Feb 1, 2017 at 8:35 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2017-02-01 20:30:30 -0500, Robert Haas wrote:
>> On Wed, Feb 1, 2017 at 7:28 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>> > On 2016-11-28 11:40:53 -0800, Jim Nasby wrote:
>> >> With current limits, the most bgwriter can do (with 8k pages) is 1000 pages
>> >> * 100 times/sec = 780MB/s. It's not hard to exceed that with modern
>> >> hardware. Should we increase the limit on bgwriter_lru_maxpages?
>> >
>> > FWIW, I think working on replacing bgwriter (e.g. by working on the
>> > patch I send with a POC replacement) wholesale is a better approach than
>> > spending time increasing limits.
>>
>> I'm happy to see it replaced, but increasing the limits is about three
>> orders of magnitude less work than replacing it, so let's not block
>> this on the theory that the other thing would be better.
>
> I seriously doubt you can meaningfully exceed 780MB/s with the current
> bgwriter. So it's not like the limits are all that relevant right now.

Sigh. The patch is harmless and there are 4 or 5 votes in favor of
it, one of which clearly states that the person involved has hit seen
it be a problem in real workloads. Do we really have to argue about
this?

--
Robert Haas
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