From: "J. Bruce Fields" Subject: Re: slowness due to splitting into pages in?nfs3svc_decode_writeargs() Date: Fri, 31 Aug 2007 17:43:06 -0400 Message-ID: <20070831214306.GO11165@fieldses.org> References: <200708312003.30446.bernd-schubert@gmx.de> <20070831184515.GC11165@fieldses.org> <200708312334.50001.bernd-schubert@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: "Brian J. Murrell" , nfs@lists.sourceforge.net To: Bernd Schubert Return-path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list2-new.sourceforge.net with esmtp (Exim 4.43) id 1IREGe-0004yj-Lc for nfs@lists.sourceforge.net; Fri, 31 Aug 2007 14:43:04 -0700 Received: from mail.fieldses.org ([66.93.2.214] helo=fieldses.org) by mail.sourceforge.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.44) id 1IREGi-0004XP-Vr for nfs@lists.sourceforge.net; Fri, 31 Aug 2007 14:43:09 -0700 In-Reply-To: <200708312334.50001.bernd-schubert@gmx.de> List-Id: "Discussion of NFS under Linux development, interoperability, and testing." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: nfs-bounces@lists.sourceforge.net Errors-To: nfs-bounces@lists.sourceforge.net On Fri, Aug 31, 2007 at 11:34:49PM +0200, Bernd Schubert wrote: > On Friday 31 August 2007, J. Bruce Fields wrote: > > There's no guarantee the later pages in the rq_pages array are > > contiguous in memory after the first one, so the rest of that iovec > > probably has random data in it. > > Hmm, its some time since I last read rfc1813, but I can't remember something > like 'data are send in pages and pages may have random order'. So I guess > some kind of multi-threading is filling in the data the client is sending? The data all arrives in one big chunk, in order. But then we have to put it some place. The kernel almost never tries to allocate more than one contiguous page of memory--memory fragmentation can make it difficult to do that reliably--so we just ask for a bunch of pages to put the data in, which may represent memory from all over the place, store those pages into an array, and receive the data into those pages in the order they're listed in the array. --b. ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs