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Date: Wed, 4 Dec 2013 17:54:10 +0100
From: Andres Freund <andres@2ndquadrant.com>
To: Metin Doslu <metin@citusdata.com>
Cc: Claudio Freire <klaussfreire@gmail.com>,
 Amit Kapila <amit.kapila16@gmail.com>,
 pgsql-hackers <pgsql-hackers@postgresql.org>,
 postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: Parallel Select query performance and shared buffers
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On 2013-12-04 18:43:35 +0200, Metin Doslu wrote:
> > I'd strongly suggest doing a "perf record -g -a <wait a bit, ctrl-c>;
> > perf report" run to check what's eating up the time.
> 
> Here is one example:
> 
> +  38.87%   swapper  [kernel.kallsyms]   [k] hypercall_page
> +   9.32%  postgres  [kernel.kallsyms]   [k] hypercall_page
> +   6.80%  postgres  [kernel.kallsyms]   [k] xen_set_pte_at

All that time is spent in your virtualization solution. One thing to try
is to look on the host system, sometimes profiles there can be more
meaningful.

Greetings,

Andres Freund

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


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