On Mon, Apr 3, 2017 at 9:58 PM, Andres Freund <andres@anarazel.de> wrote:
On 2017-03-25 19:35:35 +0300, Alexander Korotkov wrote: > On Wed, Mar 22, 2017 at 12:23 AM, David Steele <david@pgmasters.net> wrote: > > > Hi Alexander > > > > On 3/10/17 8:08 AM, Alexander Korotkov wrote: > > > > Results look good for me. Idea of committing both of patches looks > >> attractive. > >> We have pretty much acceleration for read-only case and small > >> acceleration for read-write case. > >> I'll run benchmark on 72-cores machine as well. > >> > > > > Have you had a chance to run those tests yet? > > > > I discovered an interesting issue. > I found that ccce90b3 (which was reverted) gives almost same effect as > PGXACT alignment on read-only test on 72-cores machine.
That's possibly because it changes alignment?
Probably, that needs to be checked.
> That shouldn't be related to the functionality of ccce90b3 itself, because > read-only test don't do anything with clog. And that appears to be true. > Padding of PGPROC gives same positive effect as ccce90b3. Padding patch > (pgproc-pad.patch) is attached. It's curious that padding changes size of > PGPROC from 816 bytes to 848 bytes. So, size of PGPROC remains 16-byte > aligned. So, probably effect is related to distance between PGPROC > members... > > See comparison of 16-bytes alignment of PGXACT + reduce PGXACT access vs. > padding of PGPROC.
My earlier testing had showed that padding everything is the best approach :/
I'm inclined to push this to the next CF, it seems we need a lot more benchmarking here.
