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Date:      Wed, 5 Dec 2007 11:33:40 +0900
From:      "Adrian Chadd" <adrian@freebsd.org>
To:        "Philipp Wuensche" <cryx-freebsd@h3q.com>
Cc:        "freebsd-performance@freebsd.org" <freebsd-performance@freebsd.org>
Subject:   Re: tuning for high connection rates
Message-ID:  <d763ac660712041833m259e35f4kaf1d8aedade22760@mail.gmail.com>
In-Reply-To: <4755FAD8.5030805@h3q.com>
References:  <4755ED57.6030603@h3q.com> <20071204195131.56cb1307.wmoran@collaborativefusion.com> <4755FAD8.5030805@h3q.com>

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On 05/12/2007, Philipp Wuensche <cryx-freebsd@h3q.com> wrote:

> As I understand it, and correct me if I'm wrong, polling helps against
> high interrupt rates but for that intel gigabit cards have interrupt
> moderation. We don't have a problem with interrupts (20% CPU) at the
> moment but with system (100% CPU) as you can see in the system
> monitoring graphs. Interrupts sometimes peak at, but usually are under,
> the 2k interrupts/sec limit.

Begin by reading up on the hardware profiling support (hwpmc, pmc,
etc) and see if you can get some system and process-specific profiling
information.

Kernel/System profiling will probably show you an interesting thing or
two. One thing I noticed was high in my high-TCP-transaction tests
(but not on hardware anywhere near as nice as yours!) was crypto calls
for, IIRC, syncookies.


Adrian

-- 
Adrian Chadd - adrian@freebsd.org



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