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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
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Subject: Re: Performance degradation in commit ac1d794
In-reply-to: <CEAB3A3D-FD33-4AB9-BDD3-FC0E20776245@anarazel.de>
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Comments: In-reply-to Andres Freund <andres@anarazel.de>
 message dated "Fri, 25 Dec 2015 19:20:26 +0100"
Date: Fri, 25 Dec 2015 13:28:55 -0500
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Andres Freund <andres@anarazel.de> writes:
> On December 25, 2015 7:10:23 PM GMT+01:00, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Seems like what you've got here is a kernel bug.

> I wouldn't go as far as calling it a kernel bug. Were still doing 300k tps. And were triggering the performance degradation by adding another socket (IIRC) to the poll(2) call.

Hmm.  And all those FDs point to the same pipe.  I wonder if we're looking
at contention for some pipe-related data structure inside the kernel.

			regards, tom lane


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