increasing number of lock partitions (see columns "no locks", "lwlock" and "spinlock array"). Previously it couldn't help us (see "master" column) because of a bottleneck.
If you have any other questions regarding this patch please don't hesitate to ask.
I have done some performance bench marking for this patch.(dynahash-optimization-v10-step1.patch)
Machine Detail: cpu : POWER8 cores: 24 (192 with HT)
Non Default Parameter: ------------------------ Shared Buffer= 30GB max_wal_size= 10GB max_connections=500
Test1: schema.sql and pgbench.sql are same files which Aleksander has attached in first mail of the thread.
With this test i did not see any improvement, though i think it should improve the performance, do you have any suggestion to see the results same as yours ?
I have also dump stacks using some script and I have observed many stacks dumps as you mentioned in initial thread. And after patch, I found that number of lock waiting stacks are reduced.
Stack Dump: ------------------- #0 0x00007f25842899a7 in semop () from /lib64/libc.so.6 #1 0x00000000007116d0 in PGSemaphoreLock (sema=0x7f257cb170d8) at pg_sema.c:387 #2 0x000000000078955f in LWLockAcquire (lock=0x7f247698a980, mode=LW_EXCLUSIVE) at lwlock.c:1028 #3 0x00000000007804c4 in LockAcquireExtended #4 0x000000000077fe91 in LockAcquire #5 0x000000000077e862 in LockRelationOid #6 0x000000000053bc7b in find_inheritance_children #7 0x000000000053bd4f in find_all_inheritors #8 0x00000000006fc0a2 in expand_inherited_rtentry #9 0x00000000006fbf91 in expand_inherited_tables
I have tried to analyze using perf also, I can see that amount of time taken in hash_search_with_hash_value is reduced from 3.86%(master) to 1.72%(patch).
I have plan to do further investigation, in different scenarios of dynahash.
