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Message-ID: <3C828393.7030501@candelatech.com>
Date: Sun, 03 Mar 2002 13:12:03 -0700
From: Ben Greear <greearb@candelatech.com>
Organization: Candela Technologies
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To: linux-kernel <linux-kernel@vger.kernel.org>
Subject: latency & real-time-ness.
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I have been doing some tests with 2.4.19-pre2-ac2 with
regard to network latency.  When running a steady stream of
138byte UDP packets at 115 packets per second, I see about
.1% of the packets take more than 5 miliseconds to go from
user-space to user-space on a 1Ghz PIII machine.

At 50Mbps (bi directional), I see a much wider latency spread,
with some packets taking up to 300ms or higher to get from A
to B.  The CPU load ranges from about 30% to 80% utilization
at this speed...

I'm running the program at nice -18.

So, what kind of things can I do to decrease the latency?

Would the low-latency patch help me?

Are there any scheduling tricks I can use to tell the kernel
that my program should get to run as soon as it wants to?

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>       <Ben_Greear AT excite.com>
President of Candela Technologies Inc      http://www.candelatech.com
ScryMUD:  http://scry.wanfear.com     http://scry.wanfear.com/~greear


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