Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754589AbZALM72 (ORCPT ); Mon, 12 Jan 2009 07:59:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752434AbZALM7R (ORCPT ); Mon, 12 Jan 2009 07:59:17 -0500 Received: from kandzendo.ru ([195.178.208.66]:48287 "EHLO tservice.net.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752221AbZALM7Q (ORCPT ); Mon, 12 Jan 2009 07:59:16 -0500 Date: Mon, 12 Jan 2009 15:59:14 +0300 From: Evgeniy Polyakov To: Herbert Xu Cc: Jarek Poplawski , "David S. Miller" , Jens Axboe , Willy Tarreau , Changli Gao , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: Data corruption issue with splice() on 2.6.27.10 Message-ID: <20090112125914.GA12142@ioremap.net> References: <20090106155715.GA28783@1wt.eu> <20090107093915.GA6899@ff.dom.local> <20090107122205.GA6051@1wt.eu> <20090107123153.GA9597@ff.dom.local> <20090107123504.GN32491@kernel.dk> <20090107124946.GA9677@ff.dom.local> <20090107125217.GA26235@gondor.apana.org.au> <20090112120257.GA5697@gondor.apana.org.au> <20090112124545.GA10893@ioremap.net> <20090112125607.GA6370@gondor.apana.org.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090112125607.GA6370@gondor.apana.org.au> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1358 Lines: 28 On Mon, Jan 12, 2009 at 11:56:07PM +1100, Herbert Xu (herbert@gondor.apana.org.au) wrote: > > As a long-term solution this sounds as the best case, but introduces > > quite heavy overhead for the allocators. Right now we allocate > > 1500+shared_info rounded up to the nearest power of the two (2k), but > > then we will either need to have own network allocator (I have one :) or > > allocate PAGE_SIZE+shared_info rounded up to the pwoer of the two (i.e. > > 8k), which is unfeasible. > > No that's not what I was suggesting. The page split model allocates > an skb with a very small head that accomodates only the headers. > All payload is stored in the frags structure. > > For 1500-byte packets, we can manage the payload area efficiently > by dividing each allocated page into 2K chunks. The page will > then be automatically freed once all the 2K chunks on it have been > freed through the page ref count mechanism. That's the part I referred to as a network own allocator. We can have multiple kmem_caches though for the popular MTUs and round up the requested size otherwise. -- Evgeniy Polyakov -- 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/