Re: Speed up Clog Access by increasing CLOG buffers

On 2016-03-31 17:52:12 +0530, Amit Kapila wrote:
> On Thu, Mar 31, 2016 at 3:48 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> >
> > On 2016-03-31 15:07:22 +0530, Amit Kapila wrote:
> > > On Thu, Mar 31, 2016 at 4:39 AM, Andres Freund <andres(at)anarazel(dot)de>
> wrote:
> > > >
> > > > On 2016-03-28 22:50:49 +0530, Amit Kapila wrote:
> > > > > On Fri, Sep 11, 2015 at 8:01 PM, Amit Kapila <
> amit(dot)kapila16(at)gmail(dot)com>
> > > > > wrote:
> > > > > >
> > > >
> > > > Amit, could you run benchmarks on your bigger hardware? Both with
> > > > USE_CONTENT_LOCK commented out and in?
> > > >
> > >
> > > Yes.
> >
> > Cool.
> >
> >
> > > > I think we should go for 1) and 2) unconditionally.
> >
> > > Yes, that makes sense. On 20 min read-write pgbench --unlogged-tables
> > > benchmark, I see that with HEAD Tps is 36241 and with increase the clog
> > > buffers patch, Tps is 69340 at 128 client count (very good performance
> > > boost) which indicates that we should go ahead with 1) and 2) patches.
> >
> > Especially considering the line count... I do wonder about going crazy
> > and increasing to 256 immediately. It otherwise seems likely that we'll
> > have the the same issue in a year. Could you perhaps run your test
> > against that as well?
> >
>
> Unfortunately, it dipped to 65005 with 256 clog bufs. So I think 128 is
> appropriate number.

Ah, interesting. Then let's go with that.