Hi
> I ran operf on both backends, and they look quite similar, except that the > number of samples is different (this is "opreport -c" output): > > CPU: Intel Sandy Bridge microarchitecture, speed 2899.8 MHz (estimated) > Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit > mask of 0x00 (No unit mask) count 90000 > samples % image name symbol name > > ------------------------------------------------------------------------------- > 112 0.0019 postgres ExecProcNode > 3020116 49.9904 postgres ExecScanHashBucket > 3021162 50.0077 postgres ExecHashJoin > 3020116 92.8440 postgres ExecScanHashBucket > 3020116 49.9207 postgres ExecScanHashBucket [self] > 3020116 49.9207 postgres ExecScanHashBucket > 8190 0.1354 vmlinux apic_timer_interrupt > > What could be an explanation for this? > Is this known behaviour? > one issue was fixed in 9.5 large hash table can introduce a lot of outs from L1, L2 caches. Pavel > > Yours, > Laurenz Albe > > -- > Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-performance >
