On Thu, Nov 1, 2012 at 12:51 AM, Dong Ye <yed@xxxxxxxxxx> wrote: > The average notpm is 61384.24 with 9.1.6 and 57381.43 with 9.2.1. > Plotting notps over time shows that the slowdown of 9.2.1 is evident across the entire run period. > Since we also observed sustained 80+% CPU utilization during both runs, we suspected this is a CPU bottleneck issue. > So we run oprofile hoping that the profiles may suggest one is using CPU less productively than the other; but nothing jumped out to that explanation. > The profiling results are posted on http://pgsql.privatepaste.com/3fa3ae0627 (9.1.6 run) and http://pgsql.privatepaste.com/930bb51374 (9.2.1 run). You are using prepared statements, this makes me think that this regression might be due to support for parameter specific plans for prepared statements. [1] Can you run the test on both versions without prepared statements and see if the regressions remains. I compared the profile results, I'll reproduce the results here incase they ring any other bells for someone. Here are top 20 functions that take more time under 9.2: Function Diff v9.2% v9.1% postgres.copyObject 3.48 1.2436 0.3569 postgres.check_stack_depth 1.92 0.7244 0.3774 postgres.eval_const_expressions_mutator 1.87 0.3473 0.1853 jbd./jbd 1.82 0.4127 0.2271 libc-2.14.1.so._int_malloc 1.75 1.4938 0.8540 libc-2.14.1.so.__strlen_sse42 1.72 0.7098 0.4124 vmlinux-2.6.32.59-0.7-default.copy_user_generic_string 1.70 0.5130 0.3017 postgres.MemoryContextCreate 1.68 0.3206 0.1914 postgres.MemoryContextAllocZeroAligned 1.64 1.5443 0.9443 libc-2.14.1.so._int_free 1.60 0.7182 0.4476 postgres.expression_tree_walker 1.60 0.8350 0.5235 postgres.XLogInsert 1.58 2.7251 1.7210 ext3./ext3 1.55 0.2065 0.1335 libc-2.14.1.so.__strcpy_ssse3 1.50 0.3061 0.2046 postgres.expression_tree_mutator 1.41 0.3461 0.2447 libc-2.14.1.so.__memcpy_ssse3_back 1.40 1.2379 0.8830 postgres.AllocSetAlloc 1.39 4.6567 3.3467 postgres.LockAcquireExtended 1.39 0.2799 0.2015 postgres.MemoryContextAlloc 1.38 1.0151 0.7373 postgres.AllocSetDelete 1.33 0.2130 0.1600 And top 10 functions present under 9.2 but not present with 9.1: Function postgres._copyList.isra.15 0.341 postgres._SPI_execute_plan.isra.4 0.224 postgres.grouping_planner 0.220 postgres.IndexOnlyNext 0.213 postgres.GetCachedPlan 0.189 postgres.MemoryContextStrdup 0.171 postgres.list_copy 0.165 postgres.index_getnext_tid 0.155 postgres.MemoryContextSetParent 0.128 postgres.cost_qual_eval_walker 0.127 I have no idea why is XLogInsert taking so much longer on 9.2. [1] http://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=e6faf910 Ants Aasma -- Cybertec Schönig & Schönig GmbH Gröhrmühlgasse 26 A-2700 Wiener Neustadt Web: http://www.postgresql-support.de -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
