Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 2 Jan 2003 19:05:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 2 Jan 2003 19:05:29 -0500 Received: from pc2-cwma1-4-cust86.swan.cable.ntl.com ([213.105.254.86]:16266 "EHLO irongate.swansea.linux.org.uk") by vger.kernel.org with ESMTP id ; Thu, 2 Jan 2003 19:05:28 -0500 Subject: Re: [PATCH] TCP Zero Copy for mmapped files From: Alan Cox To: "David S. Miller" Cc: lm@bitmover.com, tom@rhadamanthys.org, Linux Kernel Mailing List In-Reply-To: <20030102.151600.129375771.davem@redhat.com> References: <20030102221210.GA7704@window.dhis.org> <20030102222816.GF2461@work.bitmover.com> <1041549644.24829.66.camel@irongate.swansea.linux.org.uk> <20030102.151600.129375771.davem@redhat.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Ximian Evolution 1.0.8 (1.0.8-10) Date: 03 Jan 2003 00:56:59 +0000 Message-Id: <1041555419.24901.86.camel@irongate.swansea.linux.org.uk> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 879 Lines: 20 On Thu, 2003-01-02 at 23:16, David S. Miller wrote: > It depends how predictable your content is. With a 64bit box and a porn > server its probably quite tidy > > Let's say you have infinite VM (which is what 64-bit almost is :) then > the cost is setting up all of these useless VMAs for each and every > file (which is a 1 time cost, ok), and also the VMA lookup each > write() call. > > With sendfile() all of this goes straight to the page cache directly > without a VMA lookup. With a nasty unpleasant splat the moment you do modification on the content at all. For static objects sendfile is certainly superior, - 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/