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Date:      Mon, 7 Oct 2013 21:19:38 +0200
From:      Erik Cederstrand <erik+lists@cederstrand.dk>
To:        performance@freebsd.org
Subject:   Re: Apparent performance regression 8.3@ -> 8.4@r255966?
Message-ID:  <172AF9A7-53F7-42CF-A164-084CFB418EE9@cederstrand.dk>
In-Reply-To: <20131007172804.GA7641@albert.catwhisker.org>
References:  <20131007172804.GA7641@albert.catwhisker.org>

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Den 07/10/2013 kl. 19.28 skrev David Wolfskill <david@catwhisker.org>:

> In examining the CPU utilization graphs, the CPU generally looks
> about 5% busy for the first 15 minutes; this would be bmake =
determining
> dependency graphs, I expect.

Is that one process using 100% of one core, or many processes using 5% =
total?

> Based on earlier work I did, where I was able to do a similar build in =
a
> native FreeBSD/i386 (no PAE) enviroment on the same hardware (but when
> it still only had 6GB RAM), and I managed to get the build done in =
2:47,
> I believe that getting more work done in parallel in this 2:00 period =
is
> a key to improving performance: the 2:47 result showed that period to =
be
> a very busy one for the CPU.

You need to know where your bottlenecks are during the build. Since you =
have lots of RAM, you could try to rule out differences in filesystem =
access by placing your jail on an mfs and building your software off =
that. If that improves build times, then you're IO bound at least some =
of the time. You should be logging disk access along with CPU and memory =
during the build.

Erik=



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