Re: 答复: [HACKERS] why after increase the hash table partitions, TPMC decrease

On Tue, Sep 2, 2014 at 5:20 PM, Xiaoyulei <xiaoyulei(at)huawei(dot)com> wrote:
>
> I already modified MAX_SIMUL_LWLOCKS to make sure it is enough.

Okay.

>
>
> Total RAM is 130G, and I set shared_buffers 16G, CPU and IO is not full.
50% CPUs are idle.

As far as I understand, benchmarkSQL measures an OLTP
workload performance which means it contains mix of reads
and writes, now I am not sure how you have identified that
increasing buffer partitions can improve the performance.
Have you used any profiling?

> So I think maybe pg is blocked by some place in itself.

Yeah, there's another lock BufFreelistLock which is a major
cause of contention in buffer allocation and for which already
work is in progress for 9.5. However as mentioned previously,
that will be useful mainly for Read only loads.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com