Re: Speed up Clog Access by increasing CLOG buffers

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: David Steele <david(at)pgmasters(dot)net>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Thom Brown <thom(at)linux(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Speed up Clog Access by increasing CLOG buffers
Date: 2016-03-15 05:17:12
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On Tue, Mar 15, 2016 at 12:00 AM, David Steele <david(at)pgmasters(dot)net> wrote:
> On 2/26/16 11:37 PM, Amit Kapila wrote:
>> On Sat, Feb 27, 2016 at 10:03 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com
>> Here, we can see that there is a gain of ~15% to ~38% at higher
>> client count.
>> The attached document (perf_write_clogcontrollock_data_v6.ods)
>> contains data, mainly focussing on single client performance. The
>> data is for multiple runs on different machines, so I thought it is
>> better to present in form of document rather than dumping everything
>> in e-mail. Do let me know if there is any confusion in
>> understanding/interpreting the data.
>> Forgot to mention that all these tests have been done by
>> reverting commit-ac1d794.
> This patch no longer applies cleanly:
> $ git apply ../other/group_update_clog_v6.patch
> error: patch failed: src/backend/storage/lmgr/proc.c:404
> error: src/backend/storage/lmgr/proc.c: patch does not apply
> error: patch failed: src/include/storage/proc.h:152
> error: src/include/storage/proc.h: patch does not apply

For me, with patch -p1 < <path_of_patch> it works, but any how I have
updated the patch based on recent commit. Can you please check the latest
patch and see if it applies cleanly for you now.

> It's not clear to me whether Robert has completed a review of this code
or it still needs to be reviewed more comprehensively.
> Other than a comment that needs to be fixed it seems that all questions
have been answered by Amit.

I have updated the comments and changed the name of one of a variable from
"all_trans_same_page" to "all_xact_same_page" as pointed out offlist by

With Regards,
Amit Kapila.

Attachment Content-Type Size
group_update_clog_v7.patch application/octet-stream 15.5 KB

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