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Date:      Tue, 16 Sep 2008 11:35:59 -0700
From:      "Kevin Oberman" <oberman@es.net>
To:        "Jian Qiu" <swordqiu@gmail.com>
Cc:        freebsd-net@freebsd.org
Subject:   Re: What's the status of parallel netisr? 
Message-ID:  <20080916183559.949004500F@ptavv.es.net>
In-Reply-To: Your message of "Tue, 16 Sep 2008 22:43:25 %2B0800." <e8520310809160743v46b5cf18jd78f6043eaeccaa3@mail.gmail.com> 

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> Date: Tue, 16 Sep 2008 22:43:25 +0800
> From: "Jian Qiu" <swordqiu@gmail.com>
> Sender: owner-freebsd-net@freebsd.org
> 
> Interesting.
> 
> I did a test on local UDP throughput.
> 
> I was surprised to find out the performance with a SMP kernel was
> worse than UP. (~74MB/s v.s. 96 MB/s).

Look at CPU affinity. I have seen significant jumps in performance when
things switch between CPUs. It's best to lock the UDP cannon to a
single CPU and that the CPU not be CPU0. (This applies to both BSD and
Linux systems that I have worked with.)
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman@es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751

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