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Message-ID: <449AB69C.6090207@draigBrady.com>
Date: Thu, 22 Jun 2006 16:26:20 +0100
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To: danial_thom@yahoo.com
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Subject: Re: Dropping Packets in 2.6.17
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Danial Thom wrote:
> 
> --- Pádraig Brady <P@draigBrady.com> wrote:
> 
>>For reference with 2.4.20 on a dual 3.4GHz xeon
>>and 2 x e1000 cards, I was able to capture,
>>classify and do statistical calculations
>>on 625Kpps per interface (1.3 million pps).
> 
> Unfortunately I can do that much with FreeBSD 4.x
> with 1 2.0Ghz opteron, so its not a very
> compelling case to have to spend twice as much on
> hardware to use LINUX. However 2.4 seemed much
> better than 2.6 in this regard. 2.6 wants to drop
> a lot more packets. The goal of using 2.6 is to
> utilize DP better, but it obviously has to
> perform better than a UP Freebsd box.

NC.

> What ITR setting are using for the e1000 driver?

I didn't use ITR, I used NAPI.

>># Lots of kernel memory needed for e1000 
>>vm.min_free_kbytes = 65535 
> 
> 
> I'm curious as to why a vm setting is useful, as
> it doesn't seem that the e1000 driver uses
> virtual memory? Since rings are replenished with
> sk_buffs, and sk_buffs have to be contiguous, how
> does vm come into play?

Contiguous? The [tr]x descriptors contain
pointers to the skbufs.
Anyway I bypassed the large allocation overhead
by using skb recycling.

Pádraig.