Re: Wait free LW_SHARED acquisition - v0.9

On Sat, Oct 11, 2014 at 7:02 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
wrote:
> On Sat, Oct 11, 2014 at 6:40 PM, Andres Freund <andres(at)2ndquadrant(dot)com>
wrote:
> > On 2014-10-11 07:26:57 +0530, Amit Kapila wrote:
> > > On Sat, Oct 11, 2014 at 7:00 AM, Andres Freund <andres(at)2ndquadrant(dot)com
>
> > > > And since
> > > > your general performance numbers are a fair bit lower than what I
see
> > > > with, hopefully, the same code on the same machine...
> > >
> > > You have reported numbers at 1000 scale factor and mine were
> > > at 3000 scale factor, so I think the difference is expected.
> >
> > The numbers for 3000 show pretty much the same:
> >
> > SCALE 128 160 175
> > HEAD 352113 339005 336491
> > LW_SHARED 365874 347931 342528
> >
> > Hm. I wonder if you're using pgbench without -M prepared?
>
> No, I use below statement:
> ./pgbench -c 128 -j 128 -T 300 -S -M prepared postgres
>
> > That'd about
> > explain the difference.
>
> Here I think first thing to clarify is why the numbers on HEAD are
> different?

I have taken the latest code and recreated the database and tried
again on power-7 m/c (hydra) and below is the result:

Result with -M prepared:
Duration of each individual run - 5 mins

HEAD – commit 494affb

Shared_buffers=8GB; Scale Factor = 3000

Client Count/No. Of Runs (tps) 128 160 Run-1 258385 239908 Run-2 257835
238624 Run-3 255967 237905

Result without -M prepared:
Duration of each individual run - 5 mins

HEAD – commit 494affb

Shared_buffers=8GB; Scale Factor = 3000

Client Count/No. Of Runs (tps) 128 160 Run-1 228747 220961 Run-2 229817
214464 Run-3 227386 216619

I am not sure why we are seeing difference even though running
on same m/c with same configuration. I think there is some
difference in the way we are running tests, if you don't mind
could you please share the exact steps and non-default postgresql.conf
settings with me. The below list of things could be useful for
me to reproduce the numbers you are seeing:

a. build steps (any script you are using)
b. non-default postgresql.conf settings
c. Exact pgbench statements used

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com