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: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Dilip Kumar <dilipbalaut@gmail.com>, Robert Haas <robertmhaas@gmail.com>, Andres Freund <andres@anarazel.de>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-10-31T19:43:56Z
Lists: pgsql-hackers 
On Mon, Oct 31, 2016 at 7:58 PM, Tomas Vondra
<tomas.vondra@2ndquadrant.com> wrote:
> On 10/31/2016 02:51 PM, Amit Kapila wrote:
> And moreover, this setup (single device for the whole cluster) is very
> common, we can't just neglect it.
>
> But my main point here really is that the trade-off in those cases may not
> be really all that great, because you get the best performance at 36/72
> clients, and then the tps drops and variability increases. At least not
> right now, before tackling contention on the WAL lock (or whatever lock
> becomes the bottleneck).
>

Okay, but does wait event results show increase in contention on some
other locks for pgbench-3000-logged-sync-skip-64?  Can you share wait
events for the runs where there is a fluctuation?


-- 
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.