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Re: 2.6.7 tulip performance (with NAPI)

To: Robert Olsson <Robert.Olsson@xxxxxxxxxxx>
Subject: Re: 2.6.7 tulip performance (with NAPI)
From: Ben Greear <greearb@xxxxxxxxxxxxxxx>
Date: Wed, 06 Oct 2004 14:37:11 -0700
Cc: "'netdev@xxxxxxxxxxx'" <netdev@xxxxxxxxxxx>
In-reply-to: <16740.17875.574967.11417@xxxxxxxxxxxx>
Organization: Candela Technologies
References: <41633174.7070805@xxxxxxxxxxxxxxx> <16740.17875.574967.11417@xxxxxxxxxxxx>
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Robert Olsson wrote:
Ben Greear writes:

 > I tried setting the NICE level of pktgen to -10 and softirq to -18.  I
 > still see way more packets transmitted than received.

 If you have "max_before_softirq" in your version pktgen you can try it
 to balance your load. HZ=1000 in 2.6 can make scheduling different.

Yes, I was able to get it to smooth out by doing something like that.  I
also got better desktop performance by simply decreasing the niceness of
the pktgen thread to 0 instead of -10.

On a related note, I am now working on a way to use a hook in the
netif_wake_queue callback to wake up pktgen.  This should allow me to
have a pktgen that does not need to spin in a tight loop like it does
now.  So far, I was able to saturate two GigE ports using about 3% of
the CPU (as reported by top), using 1514 byte pkts.  Still tweaking
to fix some corner cases...

Thanks,
Ben

--
Ben Greear <greearb@xxxxxxxxxxxxxxx>
Candela Technologies Inc  http://www.candelatech.com


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