Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932102AbVKXP33 (ORCPT ); Thu, 24 Nov 2005 10:29:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932105AbVKXP33 (ORCPT ); Thu, 24 Nov 2005 10:29:29 -0500 Received: from ns.suse.de ([195.135.220.2]:6810 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S932102AbVKXP32 (ORCPT ); Thu, 24 Nov 2005 10:29:28 -0500 Date: Thu, 24 Nov 2005 16:29:24 +0100 From: Andi Kleen To: Avi Kivity Cc: Andi Kleen , Benjamin LaHaise , Jeff Garzik , Andrew Grover , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, john.ronciak@intel.com, christopher.leech@intel.com Subject: Re: [RFC] [PATCH 0/3] ioat: DMA engine support Message-ID: <20051124152924.GB5921@wotan.suse.de> References: <4384E7F2.2030508@pobox.com> <20051123223007.GA5921@wotan.suse.de> <20051124001700.GC14246@kvack.org> <20051124065037.GZ20775@brahms.suse.de> <4385DB32.7010605@argo.co.il> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4385DB32.7010605@argo.co.il> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1448 Lines: 45 On Thu, Nov 24, 2005 at 05:24:34PM +0200, Avi Kivity wrote: > Andi Kleen wrote: > > >>Don't forget that there are benefits of not polluting the cache with the > >>traffic for the incoming skbs. > >> > >> > > > >Is that a general benefit outside benchmarks? I would expect > >most real programs to actually do something with the data > >- and that usually involves needing it in cache. > > > > > > > As an example, an NFS server reads some data pages using iSCSI and sends > them using NFS/TCP (or vice versa). For TX this can be done zero copy using a sendfile like setup. For RX it may help - but my point was that most applications are not structured in this simple way. > >>In the I/O AT case it might make sense to do a few prefetch()es of the > >>userland data on the return-to-userspace code path. > >> > >> > > > >Some prefetches for user space might be a good idea yes > > > > > > > As long as they can be turned off. Not all usespace applications want to > touch the data immediately. Perhaps. And lots of others might. Of course the simple network benchmarks don't so the number on them look good. Just pointing out that it's not clear it will always be a big help. -Andi - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/