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Re: [HACKERS] pg_stat_wal_write statistics view - Mailing list pgsql-hackers

From Haribabu Kommi
Subject Re: [HACKERS] pg_stat_wal_write statistics view
Date
Msg-id CAJrrPGfyDWUfHVQET_+spsboSaTWTHv31k_-9tnKvCXnJcsnMA@mail.gmail.com
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In response to Re: [HACKERS] pg_stat_wal_write statistics view  (Haribabu Kommi <kommi.haribabu@gmail.com>)
Responses Re: [HACKERS] pg_stat_wal_write statistics view
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On Mon, Nov 27, 2017 at 2:12 PM, Haribabu Kommi <kommi.haribabu@gmail.com> wrote:

On Wed, Nov 8, 2017 at 8:46 AM, Robert Haas <robertmhaas@gmail.com> wrote:
On Tue, Nov 7, 2017 at 4:31 AM, Haribabu Kommi <kommi.haribabu@gmail.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
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