From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olof Johansson Subject: Re: [PATCH 0/10] [IOAT] I/OAT patches repost Date: Thu, 20 Apr 2006 23:42:50 -0500 Message-ID: <20060421044250.GO26746@pb15.lixom.net> References: <20060420213305.GK26746@pb15.lixom.net> <20060420.172742.132879746.davem@davemloft.net> <20060421030426.GM26746@pb15.lixom.net> <20060420.204200.103377406.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: olof@lixom.net, andrew.grover@intel.com, netdev@vger.kernel.org Return-path: Received: from lixom.net ([66.141.50.11]:14298 "EHLO mail.lixom.net") by vger.kernel.org with ESMTP id S932094AbWDUEnp (ORCPT ); Fri, 21 Apr 2006 00:43:45 -0400 To: "David S. Miller" Content-Disposition: inline In-Reply-To: <20060420.204200.103377406.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, Apr 20, 2006 at 08:42:00PM -0700, David S. Miller wrote: > This is basically why none of the performance gains add up to me. I > am thus very concerned that the current non-cache-warming > implmentation may fall flat performance wise. Ok, I buy your arguments. It does seems unlikely that a DMA offload without cache warmth will be a net gain. More performance data is definitely be required. After digging after PDFs, it seems as the Freescale 85xx (at least, probably earlier models as well) can warm L2 for the DMA destination data. However, I don't have any hardware with it to play around with for benchmarking to see what cache warming might bring (back), performance-wise. I think there is still use for a common multi-function DMA framework across platforms and client components, even if net receive doesn't end up being {a,the first} user. -Olof