Horton

Re: Speed up Clog Access by increasing CLOG buffers

David Steele <david@pgmasters.net>

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From: David Steele <david@pgmasters.net>
To: Amit Kapila <amit.kapila16@gmail.com>, Robert Haas <robertmhaas@gmail.com>
Cc: Thom Brown <thom@linux.com>, Simon Riggs <simon@2ndquadrant.com>, Jesper Pedersen <jesper.pedersen@redhat.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-03-14T18:30:05Z
Lists: pgsql-hackers 
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

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.

Is this "ready for committer" or still in need of further review?

-- 
-David
david@pgmasters.net

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.