From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265656AbUBFT0c (ORCPT ); Fri, 6 Feb 2004 14:26:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265658AbUBFT0b (ORCPT ); Fri, 6 Feb 2004 14:26:31 -0500 Received: from post.tau.ac.il ([132.66.16.11]:56753 "EHLO post.tau.ac.il") by vger.kernel.org with ESMTP id S265656AbUBFT02 (ORCPT ); Fri, 6 Feb 2004 14:26:28 -0500 Date: Fri, 6 Feb 2004 21:26:18 +0200 From: Micha Feigin To: lkml Subject: Re: reiserfs - difference between a commit and a transaction Message-ID: <20040206192618.GE2582@luna.mooo.com> Mail-Followup-To: lkml References: <20040206002346.GA2571@luna.mooo.com> <16419.22749.486759.348150@laputa.namesys.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <16419.22749.486759.348150@laputa.namesys.com> User-Agent: Mutt/1.5.5.1+cvs20040105i X-AntiVirus: checked by Vexira MailArmor (version: 2.0.1.16; VAE: 6.23.0.3; VDF: 6.23.0.60; host: localhost) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 06, 2004 at 12:05:33PM +0300, Nikita Danilov wrote: > Micha Feigin writes: > > I am trying to do some work on reiserfs to make it laptop-mode > > compliant. After looking at the code because it was still noisy after I > > thought I told correctly to be quite, raised a question that I was > > hoping someone can clarify for me. > > > > Reiserfs has both a transaction and a commit and I was wondering what > > is which. > > Transaction is a sequence of file system modifications that (by the > virtue of file system implementation) is bound to either be completed as > a whole or be aborted as a whole (this is called "atomicity"). > > Commit is a certain operation performed during transaction life-time to > implement its atomicity. > So, at what time of a transaction's life would a commit be flushed to disk, only in the process of flushing the transaction to disk or at several points during its life time to make sure that atomicity is preserved. And on that note, can there be several transactions active at one time or is a new transaction created only when the previous is closed and ready to flush. > > > > (I am mostly interested in this from the point of what max_trans_age > > and max_commit_age affect) > > Take a look at the "commit" mount option of reiserfs. > Thats what I was looking at and what I ported to 2.4 (it did require a fix for laptop mode to enable reseting the value, but that will be coming shortly). The problem was that reiserfs was still being very noisy (kreiserfsd was writing to disk around every 30 seconds despite beeing mounted with commit=600). That led me to look further into the code and changing max_trans_age instead of max_commit_age kept it quite for the full ten minutes. I am still checking to make sure that its not something with me or my system. For laptop mode we want to keep disk activity quiet for around ten minutes at a time so that the disk can be spun down, thus sacrificing the chance of loosing data for battery life. I am trying to see what is the right value to change and what is the meaning of changing it but I could only find old documentation and the comments in the code are good only for people who know the meaning of the terms in the first place. > > > > Thanks > > Nikita. > - > 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/ >