On 2015-01-26 19:58:25 -0500, Bruce Momjian wrote: > On Tue, Jan 27, 2015 at 01:43:41AM +0100, Andres Freund wrote: > > master + 32align.patch: > > -c max_connections=400 > > tps = 183791.872359 (high run vs. run variability) > > -c max_connections=401 > > tps = 185494.98244 (high run vs. run variability) > > > > master + 64align.patch: > > -c max_connections=400 > > tps = 489257.195570 > > -c max_connections=401 > > tps = 490496.520632 > > > > Pretty much as expected, rigth? > > Yes, I am convinced. Let's work on a patch now.
Since I can reproduce some minor (1-3%) performance *regressions* at low client counts when aligning every shmem allocation, I'm inclined to just add special case code to BufferShmemSize()/InitBufferPool() to align descriptors to PG_CACHE_LINE_SIZE. That's really unlikely to regress anythign as it basically can't be a bad idea to align buffer descriptors. Contrary opinions? Robert? Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers