Date: Thu, 31 Jul 2014 17:38:08 -0400
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Matt Clarkson <mattc@catalyst.net.nz>
Cc: pgsql-performance@postgresql.org
Subject: Re: 60 core performance with 9.3
Message-ID: <20140731213807.GD5475@eldon.alvh.no-ip.org>
References: 
 <CAOR=d=3=Y6yNtwQenwVBGe6ZgjAeA8PwgYb3=aQEKn+vYWhBJA@mail.gmail.com>
 <53ACD6C4.9050605@catalyst.net.nz>
 <20140627091951.GA16680@awork2.anarazel.de>
 <53B283F3.7020005@catalyst.net.nz>
 <20140701101307.GO21422@awork2.anarazel.de>
 <53BF326F.2070903@catalyst.net.nz>
 <20140711082207.GI17261@awork2.anarazel.de>
 <53C711B6.5040802@catalyst.net.nz> <53D84E16.90609@catalyst.net.nz>
 <1406763363.7654.73.camel@oldgreg.wgtn.cat-it.co.nz>
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Matt Clarkson wrote:

> The LWLOCK_STATS below suggest that ProcArrayLock might be the main
> source of locking that's causing throughput to take a dive as the client
> count increases beyond the core count.

> Any thoughts or comments on these results are welcome!

Do these results change if you use Heikki's patch for CSN-based
snapshots?  See
http://www.postgresql.org/message-id/539AD153.9000004@vmware.com for the
patch (but note that you need to apply on top of 89cf2d52030 in the
master branch -- maybe it applies to HEAD the 9.4 branch but I didn't
try).

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


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