From: Tom Lane <tgl@sss.pgh.pa.us>
To: Noah Misch <noah@leadboat.com>
Cc: Robert Haas <robertmhaas@gmail.com>
Cc: Васильев Дмитрий <d.vasilyev@postgrespro.ru>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: Performance degradation in commit ac1d794
Date: Tue, 31 May 2016 22:23:29 -0400
Message-ID: <14760.1464747809@sss.pgh.pa.us> (raw)
In-Reply-To: <20160601022005.GB596188@tornado.leadboat.com>
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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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Cc: tgl@sss.pgh.pa.us, noah@leadboat.com, robertmhaas@gmail.com, d.vasilyev@postgrespro.ru
Subject: Re: Performance degradation in commit ac1d794
In-Reply-To: <14760.1464747809@sss.pgh.pa.us>
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