Re: [HACKERS] pg_stat_wal_write statistics view

On Mon, Nov 27, 2017 at 2:12 PM, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>
wrote:

>
> On Wed, Nov 8, 2017 at 8:46 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
>> On Tue, Nov 7, 2017 at 4:31 AM, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>
>> wrote:
>> >> Updated patch attached.
>> > Patch rebased.
>>
>> I think the earlier concerns about the performance impact of this are
>> probably very valid concerns, and I don't see how the new version of
>> the patch gets us much closer to solving them.
>>
>
> I will check the performance with the changes of removing the stats
> collector
> usage and provide the details.
>

I ran the pgbench performance after removing stats collector usage and
moving
the stats into shared memory. I find it that this stats addition doesn't
have any
overhead while collecting the stats. I ran these tests on a small machine,
these may
need to be retested on an high end machine to confirm that there is no
impact.

Threads Clients HEAD PATCH Diff
1 1 88.72981533 88.527789 -0.23%
2 2 88.17999 88.823842 0.73%
4 4 169.430813 167.897937 -0.90%
8 8 311.790313 315.6659117 1.24%
16 16 558.6014777 562.5883583 0.71%
32 32 874.0996587 899.855634 2.95%

Attached is the updated patch accordingly to use the shared memory stats.

Regards,
Hari Babu
Fujitsu Australia