From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964821AbWFHK6E (ORCPT ); Thu, 8 Jun 2006 06:58:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964820AbWFHK6E (ORCPT ); Thu, 8 Jun 2006 06:58:04 -0400 Received: from ns.virtualhost.dk ([195.184.98.160]:8479 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S964818AbWFHK6C (ORCPT ); Thu, 8 Jun 2006 06:58:02 -0400 Date: Thu, 8 Jun 2006 13:00:45 +0200 From: Jens Axboe To: Hans Reiser Cc: Tom Vier , Linux-Kernel@vger.kernel.org, Reiserfs developers mail-list , Reiserfs mail-list Subject: Re: [PATCH] updated reiser4 - reduced cpu usage for writes by writing more than 4k at a time (has implications for generic write code and eventually for the IO layer) Message-ID: <20060608110044.GA5207@suse.de> References: <44736D3E.8090808@namesys.com> <20060524175312.GA3579@zero> <44749E24.40203@namesys.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <44749E24.40203@namesys.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 24 2006, Hans Reiser wrote: > Tom Vier wrote: > > >On Tue, May 23, 2006 at 01:14:54PM -0700, Hans Reiser wrote: > > > > > >>underlying FS can be improved. Performance results show that the new > >>code consumes 40% less CPU when doing "dd bs=1MB ....." (your hardware, > >>and whether the data is in cache, may vary this result). Note that this > >>has only a small effect on elapsed time for most hardware. > >> > >> > > > >Write requests in linux are restricted to one page? > > > > > > > It may go to the kernel as a 64MB write, but VFS sends it to the FS as > 64MB/4k separate 4k writes. Nonsense, there are ways to get > PAGE_CACHE_SIZE writes in one chunk. Other file systems have been doing it for years. -- Jens Axboe