From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030297AbXDWXzQ (ORCPT ); Mon, 23 Apr 2007 19:55:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030307AbXDWXzQ (ORCPT ); Mon, 23 Apr 2007 19:55:16 -0400 Received: from terminus.zytor.com ([192.83.249.54]:51319 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030297AbXDWXzO (ORCPT ); Mon, 23 Apr 2007 19:55:14 -0400 Message-ID: <462D46DF.4090802@zytor.com> Date: Mon, 23 Apr 2007 16:53:03 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 1.5.0.10 (X11/20070302) MIME-Version: 1.0 To: Theodore Tso , Eric Hopper , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: Question about Reiser4 References: <462C2E5B.1080008@redhat.com> <462C4858.3050006@redhat.com> <462C4D32.4000909@redhat.com> <462C5034.9090403@redhat.com> <20070423010445.454eda63.akpm@linux-foundation.org> <20070423135216.GA2744@omnifarious.org> <20070423225640.GA1663@thunk.org> In-Reply-To: <20070423225640.GA1663@thunk.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Theodore Tso wrote: > > One of the big problems of using a filesystem as a DB is the system > call overheads. If you use huge numbers of tiny files, then each > attempt read an atom of information from the DB takes three system > calls --- an open(), read(), and close(), with all of the overheads in > terms of dentry and inode cache. > Now, to be fair, there are probably a number of cases where open/lseek/readv/close and open/lseek/writev/close would be worth doing as a single system call. The big problem as far as I can see involves EINTR handling; such a system call has serious restartability implications. Of course, there are Ingo's syslets... -hpa