Horton

Re: Speed up Clog Access by increasing CLOG buffers

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: David Steele <david@pgmasters.net>
Cc: Robert Haas <robertmhaas@gmail.com>, Thom Brown <thom@linux.com>, Simon Riggs <simon@2ndquadrant.com>, Jesper Pedersen <jesper.pedersen@redhat.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-03-15T05:17:12Z
Lists: pgsql-hackers

Attachments

On Tue, Mar 15, 2016 at 12:00 AM, David Steele <david@pgmasters.net> wrote:
>
> On 2/26/16 11:37 PM, Amit Kapila wrote:
>
>> On Sat, Feb 27, 2016 at 10:03 AM, Amit Kapila <amit.kapila16@gmail.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
Alvaro.


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

Commits

  1. Use group updates when setting transaction status in clog.

  2. Improve 64bit atomics support.

  3. Add ProcArrayGroupUpdate wait event.

  4. Make the different Unix-y semaphore implementations ABI-compatible.

  5. Fix broken ALTER INDEX documentation

  6. Code and docs review for commit 3187d6de0e5a9e805b27c48437897e8c39071d45.

  7. Partition the freelist for shared dynahash tables.

  8. Correct StartupSUBTRANS for page wraparound

  9. Make idle backends exit if the postmaster dies.

  10. contrib/sslinfo: add ssl_extension_info SRF

  11. Reduce ProcArrayLock contention by removing backends in batches.

  12. Fix `make installcheck` for serializable transactions.

  13. Lockless StrategyGetBuffer clock sweep hot path.

  14. Reduce sinval synchronization overhead.