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Re: RFC: NAPI packet weighting patch

To: "David S. Miller" <davem@xxxxxxxxxx>
Subject: Re: RFC: NAPI packet weighting patch
From: Andi Kleen <ak@xxxxxxx>
Date: Thu, 23 Jun 2005 01:23:45 +0200
Cc: ak@xxxxxxx, leonid.grossman@xxxxxxxxxxxx, davem@xxxxxxxxxxxxx, hadi@xxxxxxxxxx, becker@xxxxxxxxx, rick.jones2@xxxxxx, netdev@xxxxxxxxxxx
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On Wed, Jun 22, 2005 at 07:19:56PM -0400, David S. Miller wrote:
> From: Andi Kleen <ak@xxxxxxx>
> Date: Thu, 23 Jun 2005 01:13:00 +0200
> 
> > The computing time must be quite long to be really a win.
> > You need to waste a few hundred cycles at least on a modern fast CPU.
> 
> SKB allocation more than fits this requirement, and that is exactly
> what the RX descriptor replenishment will do.

It shouldn't in theory. Unless they did something bad to the slab
allocator again when I wasn't looking ;-) 

> 
> Even if SKB allocation was only half the necessary number of cycles
> for the prefetch to hit the cpu, it'd still be a win.

If it's too small then it might be left in the noise.

-Andi

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