On Thu, Dec 10, 2009 at 3:58 PM, Alvaro Herrera <alvhe...@commandprompt.com> wrote: > Jaime Casanova escribió: >> On Wed, Dec 9, 2009 at 9:39 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: >> > so I'd like some independent confirmation that it does. >> > >> >> what kind of tests could show that? or simply running pgbench several >> times for 15 minutes each run could show any benefit? > > Isn't the supposed performance improvement in this patch linked strongly > to backup blocks? If that's really the case, I think it would show more > prominently if you had very frequent checkpoints. >
Ah! Ok, i was only following the logic that it was eliminating the need of executing a loop twice... But you are right while the loop executes always it only do something meaningful after a checkpoint and the for statement only make 3 loops each, because XLR_MAX_BKP_BLOCKS is defined as 3 in src/include/access/xlog.h looked that way seems like the benefit could be only marginal to prove that i compile with and without the patch, and change checkpoint_segments = 1 and checkpoint_timeout = 1min to force frequent checkpoints (actually they ocurred a few seconds apart) initialize the pgbench database in each installation with: pgbench -i -s 200 -F 90 test and executed 6 times with: pgbench -n -c 50 -j 5 -l -T 900 test Results are: Min (tps) Unpatched - including connections establishing 133.046069 excluding it 133.085274 Patched - including connections establishing 139.567284 excluding it 139.591229 Max (tps) Unpatched - including connections establishing 147.082181 excluding it 147.108752 Patched - including connections establishing 151.276416 excluding it 151.311745 Avg (tps) Unpatched - including connections establishing 140.750998 excluding it 140.790336 Patched - including connections establishing 146.383735 excluding it 146.411039 So in this extreme case avg tps is just 6 transactions better PS: i'm attaching the files i use for the tests -- Atentamente, Jaime Casanova Soporte y capacitación de PostgreSQL Asesoría y desarrollo de sistemas Guayaquil - Ecuador Cel. +59387171157
test_patched.sh
Description: Bourne shell script
test_unpatched.sh
Description: Bourne shell script
-- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers