From: Theodore Tso Subject: Re: tracepoints in ext4 (and/or ext3?) Date: Tue, 12 Aug 2008 12:32:32 -0400 Message-ID: <20080812163232.GC8857@mit.edu> References: <48A09E7F.7060605@redhat.com> <20080812081954.5f5eeb10@gara> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Eric Sandeen , ext4 development To: "Jose R. Santos" Return-path: Received: from www.church-of-our-saviour.org ([69.25.196.31]:36791 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750987AbYHLQcv (ORCPT ); Tue, 12 Aug 2008 12:32:51 -0400 Content-Disposition: inline In-Reply-To: <20080812081954.5f5eeb10@gara> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Aug 12, 2008 at 08:19:54AM -0500, Jose R. Santos wrote: > > Good idea, although Im not sure if ext[34] is the best place we should > start putting markers though. I can think of ext3/4 specific markers that would be useful for people who are tuning our filesystems for performance. This would include when we start and end tranactions, when we force a checkpoint, when we create and, extend, and finish using a handle in the jbd layer. In the ext4 itself, knowing when we are mapping delayed allocations would be useful, as well as when we freeze and unfreeze a filesystem (i.e., for snapshots). There are a lot of other tracepoints that probably do make more sense to be put in the VFS layer, although on thing that would be *really* nice is some semantic sugar in Systemtap or in a Systemtap tapset so that we only trigger the tracepoints for a particular filesystem. - Ted