Re: Memory Accounting v11

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От David Rowley
Тема Re: Memory Accounting v11
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Msg-id CAKJS1f_n=_7BdeS_6Jj3O8Z6H2+o5wk5XHSwMTvmHZ4OSTCq9g@mail.gmail.com
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Ответ на Memory Accounting v11  (Jeff Davis <pgsql@j-davis.com>)
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On 15 June 2015 at 07:43, Jeff Davis <pgsql@j-davis.com> wrote:

* There was a slowdown reported of around 1-3% (depending on the exact
version of the patch) on an IBM power machine when doing an index
rebuild. The results were fairly noisy for me, but it seemed to hold up.
See http://www.postgresql.org/message-id/CA
+Tgmobnu7XEn1gRdXnFo37P79bF=qLt46=37ajP3Cro9dBRaA@mail.gmail.com

Hi Jeff,

I've been looking over the code and reason the previous emails about this patch.
I don't yet understand if the reported slowdown is from the increase in struct size or from the additional work being done in palloc() calls, however, on reading the code I did notice an existing redundant NULL check in AllocSetAlloc() right where you put you're extra accounting code.

The attached patch should apply on top of your patch and removes the extra NULL check.

Perhaps if some over the overhead is the extra instructions then this can help get us back to where we were before.

Regards

David Rowley
 
--
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services
 
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