From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030185AbXDXLPU (ORCPT ); Tue, 24 Apr 2007 07:15:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030188AbXDXLPU (ORCPT ); Tue, 24 Apr 2007 07:15:20 -0400 Received: from wr-out-0506.google.com ([64.233.184.224]:33652 "EHLO wr-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030185AbXDXLPS (ORCPT ); Tue, 24 Apr 2007 07:15:18 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=mve4glj3ZcoOazqwHn5wQJf8/GqO4rTJWt+ppIYjqrP+v5LVO/lIGtgpya/mTxFmQv0RnsHLEpFuymiBs23zcShWl9sjm1Nw+oSzfVexh6XdPNEK5Huza6Q0CAnlzYLxEXDve3pSI51hd+j4UYHV+ndNtZAEcSsTpwWzppQ/Vjg= Message-ID: <1158166a0704240415i4cb2e29ep1a556d3aa379476c@mail.gmail.com> Date: Tue, 24 Apr 2007 13:15:17 +0200 From: "Denis Vlasenko" To: "Theodore Tso" , "Eric Hopper" , "Andrew Morton" , linux-kernel@vger.kernel.org Subject: Re: Question about Reiser4 In-Reply-To: <20070424011753.GD1663@thunk.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <462C4D32.4000909@redhat.com> <462C5034.9090403@redhat.com> <20070423010445.454eda63.akpm@linux-foundation.org> <20070423135216.GA2744@omnifarious.org> <20070423225640.GA1663@thunk.org> <462D46DF.4090802@zytor.com> <20070424001934.GC1663@thunk.org> <462D4FE1.5040406@zytor.com> <20070424011753.GD1663@thunk.org> 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... I definitely would like open/readv/close syscall a lot. Actually, a set of four syscalls open/readv/close open/pread/close open/writev/close open/pwrite/close will allow to reduce syscall overhead for a number of cases. -- vda