Re: Patch: fix lock contention for HASHHDR.mutex

On Wed, Jan 27, 2016 at 5:15 PM, Aleksander Alekseev <
a(dot)alekseev(at)postgrespro(dot)ru> wrote:

> Most likely HASHHDR.mutex is not only bottleneck in your case so my
> patch doesn't help much. Unfortunately I don't have access to any
> POWER8 server so I can't investigate this issue. I suggest to use a
> gettimeofday trick I described in a first message of this thread. Its
> time consuming but it gives a clear understanding which code is keeping
> a lock.
>

I have also tested the pgbench Readonly test when data don't fit into
shared buffer,
Because in this case HASHHDR.mutex access will be quite frequent.
And in this case i do see very good improvement in POWER8 server.

Test Result:
------------
Scale Factor: 300
Shared Buffer: 512MB
pgbench -c$ -j$ -S -M Prepared postgres

Client base patch
64 222173 318318
128 195805 262290

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com