From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: Re: [PATCH 12/35] undo-io: use a bitmap to track what we've already written Date: Tue, 5 May 2015 10:21:45 -0400 Message-ID: <20150505142145.GD12468@thunk.org> References: <20150402023359.25243.79782.stgit@birch.djwong.org> <20150402023519.25243.93058.stgit@birch.djwong.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: "Darrick J. Wong" Return-path: Received: from imap.thunk.org ([74.207.234.97]:45875 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2993159AbbEEOVp (ORCPT ); Tue, 5 May 2015 10:21:45 -0400 Content-Disposition: inline In-Reply-To: <20150402023519.25243.93058.stgit@birch.djwong.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Apr 01, 2015 at 07:35:19PM -0700, Darrick J. Wong wrote: > It's really inefficient to (ab)use the TDB key store as a bitmap to > find out if we've already written a block to the undo file, because > the tdb code is reads the database key btree disk blocks for *every* > query. Changing that logic to a bitmap reduces overhead by a large > margin -- the overhead of using undo_io while converting a 2TB FS to > metadata_csum is reduced from 55 minutes to 45. > > Signed-off-by: Darrick J. Wong Thanks, applied. - Ted