Re: Performance degradation in commit ac1d794 - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Performance degradation in commit ac1d794
Date
Msg-id 14760.1464747809@sss.pgh.pa.us
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In response to Re: Performance degradation in commit ac1d794  (Noah Misch <noah@leadboat.com>)
Responses Re: Performance degradation in commit ac1d794  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
Noah Misch <noah@leadboat.com> writes:
> On Tue, May 31, 2016 at 10:09:05PM -0400, Robert Haas wrote:
>> What I *think* is going on here is:
>> - ac1d794 lowered performance
>> - backend_flush_after with a non-zero default lowered performance with
>> a vengeance
>> - 98a64d0 repaired the damage done by ac1d794, or much of it, but
>> Mithun couldn't see it in his benchmarks because backend_flush_after>0
>> is so bad

> Ashutosh Sharma's measurements do bolster that conclusion.

>> That could be wrong, but I haven't seen any evidence that it's wrong.
>> So I'm inclined to say we should just move this open item back to the
>> CLOSE_WAIT list (adding a link to this email to explain why we did
>> so).  Does that work for you?

> That works for me.  

Can we make a note to re-examine this after the backend_flush_after
business is resolved?  Or at least get Mithun to redo his benchmarks
with backend_flush_after set to zero?
        regards, tom lane



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