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: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-03-31T09:37:22Z
Lists: pgsql-hackers

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On Thu, Mar 31, 2016 at 4:39 AM, Andres Freund <andres@anarazel.de> wrote:
>
> On 2016-03-28 22:50:49 +0530, Amit Kapila wrote:
> > On Fri, Sep 11, 2015 at 8:01 PM, Amit Kapila <amit.kapila16@gmail.com>
> > wrote:
> > >
>
> Amit, could you run benchmarks on your bigger hardware? Both with
> USE_CONTENT_LOCK commented out and in?
>

Yes.

> I think we should go for 1) and 2) unconditionally.


Yes, that makes sense.  On 20 min read-write pgbench --unlogged-tables
benchmark, I see that with HEAD Tps is 36241 and with increase the clog
buffers patch, Tps is 69340 at 128 client count (very good performance
boost) which indicates that we should go ahead with 1) and 2) patches.

0002-Increase-max-number-of-buffers-in-clog-SLRU-to-128

Size

 CLOGShmemBuffers(void)

 {

- return Min(32, Max(4, NBuffers / 512));

+ return Min(128, Max(4, NBuffers / 512));

 }


I think we should change comments on top of this function.  I have changed
the comments as per my previous patch and attached the modified patch with
this mail, see if that makes sense.


0001-Improve-64bit-atomics-support

+#if 0
+#ifndef PG_HAVE_ATOMIC_READ_U64
+#define PG_HAVE_ATOMIC_READ_U64
+static inline uint64

What the purpose of above #if 0?  Other than that patch looks good to me.


> And then evaluate
> whether to go with your, or 3) from above. If the latter, we've to do
> some cleanup :)
>

Yes, that makes sense to me, so lets go with 1) and 2) first.

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.