Horton

Re: Speed up Clog Access by increasing CLOG buffers

Tomas Vondra <tomas.vondra@2ndquadrant.com>

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From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-09-06T19:38:35Z
Lists: pgsql-hackers 

On 09/06/2016 04:49 AM, Amit Kapila wrote:
> On Mon, Sep 5, 2016 at 11:34 PM, Tomas Vondra
> <tomas.vondra@2ndquadrant.com> wrote:
>>
>>
>> On 09/05/2016 06:03 AM, Amit Kapila wrote:
>>>  So, in short we have to compare three
>>> approaches here.
>>>
>>> 1) Group mode to reduce CLOGControlLock contention
>>> 2) Use granular locking model
>>> 3) Use atomic operations
>>>
>>> For approach-1, you can use patch [1].  For approach-2, you can use
>>> 0001-Improve-64bit-atomics-support patch[2] and the patch attached
>>> with this mail.  For approach-3, you can use
>>> 0001-Improve-64bit-atomics-support patch[2] and the patch attached
>>> with this mail by commenting USE_CONTENT_LOCK.  If the third doesn't
>>> work for you then for now we can compare approach-1 and approach-2.
>>>
>>
>> OK, I can compile all three cases - but onl with gcc 4.7 or newer. Sadly
>> the 4-socket 64-core machine runs Debian Jessie with just gcc 4.6 and my
>> attempts to update to a newer version were unsuccessful so far.
>>
> 
> So which all patches your are able to compile on 4-socket m/c?  I
> think it is better to measure the performance on bigger machine.

Oh, sorry - I forgot to mention that only the last test (with
USE_CONTENT_LOCK commented out) fails to compile, because the functions
for atomics were added in gcc-4.7.


regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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.