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@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
