From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ted Ts'o Subject: Re: [PATCH 2/5] ext4: speed up group trim with the right free block count. Date: Mon, 11 Jul 2011 00:06:58 -0400 Message-ID: <20110711040658.GF28763@thunk.org> References: <4E0DE63A.7030103@tao.ma> <1309534076-2784-1-git-send-email-tm@tao.ma> <1309534076-2784-2-git-send-email-tm@tao.ma> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org To: Tao Ma Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:55474 "EHLO test.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750913Ab1GKEHB (ORCPT ); Mon, 11 Jul 2011 00:07:01 -0400 Content-Disposition: inline In-Reply-To: <1309534076-2784-2-git-send-email-tm@tao.ma> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, Jul 01, 2011 at 11:27:53PM +0800, Tao Ma wrote: > From: Tao Ma > > When we trim some free blocks in a group of ext4, we should > calculate the free blocks properly and check whether there are > enough freed blocks left for us to trim. Current solution will > only calculate free spaces if they are large for a trim which > isn't appropriate. > > Let us see a small example: > a group has 1.5M free which are 300k, 300k, 300k, 300k, 300k. > And minblocks is 1M. With current solution, we have to iterate > the whole group since these 300k will never be subtracted from > 1.5M. But actually we should exit after we find the first 2 > free spaces since the left 3 chunks only sum up to 900K if we > subtract the first 600K although they can't be trimed. > > Reviewed-by: Andreas Dilger > Signed-off-by: Tao Ma Added to the ext4 tree, thanks. - Ted