From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: RFC: NAPI packet weighting patch Date: Thu, 23 Jun 2005 01:23:45 +0200 Message-ID: <20050622232345.GD14251@wotan.suse.de> References: <20050622.132241.21929037.davem@davemloft.net> <200506222242.j5MMgbxS009935@guinness.s2io.com> <20050622231300.GC14251@wotan.suse.de> <20050622.191956.39166724.davem@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: ak@suse.de, leonid.grossman@neterion.com, davem@davemloft.net, hadi@cyberus.ca, becker@scyld.com, rick.jones2@hp.com, netdev@oss.sgi.com Return-path: To: "David S. Miller" Content-Disposition: inline In-Reply-To: <20050622.191956.39166724.davem@redhat.com> Sender: netdev-bounce@oss.sgi.com Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org On Wed, Jun 22, 2005 at 07:19:56PM -0400, David S. Miller wrote: > From: Andi Kleen > 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