Re: Time to up bgwriter_lru_maxpages?

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.