From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id p4JLsUo4055980 for ; Thu, 19 May 2011 16:54:30 -0500 Subject: Re: [PATCH 2/4] xfs: do not discard alloc btree blocks From: Alex Elder In-Reply-To: <20110504190011.319521066@bombadil.infradead.org> References: <20110504185513.136746538@bombadil.infradead.org> <20110504190011.319521066@bombadil.infradead.org> Date: Thu, 19 May 2011 16:54:29 -0500 Message-ID: <1305842069.2825.88.camel@doink> MIME-Version: 1.0 Reply-To: aelder@sgi.com List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Christoph Hellwig Cc: xfs@oss.sgi.com On Wed, 2011-05-04 at 14:55 -0400, Christoph Hellwig wrote: > Blocks for the allocation btree are allocated from and release to > the AGFL, and thus frequently reused. Even worse we do not have > an easy way to avoid using an AGFL block when it is discarded due > to the simple FILO list of free blocks, and thus can frequently > stall on blocks that are currently undergoing a discard. > > Add a flag to the busy extent tracking structure to skip the discard for > allocation btree blocks. In normal operation these blocks are reused > frequently enough that there is no need to discard them anyway, but > if they spill over to the allocation btree as part of a balance we > "leak" blocks that we would otherwise discard. We could fix this > by adding another flag and keeping these block in the rbtree even > after they aren't busy any more so that we could discard them when > they migrate out of the AGFL. Given that this would cause significant > overhead I don't think it's worthwile for now. > > Signed-off-by: Christoph Hellwig This one looks good. (If you add support for discard with nodelaylog it will need to be updated.) Reviewed-by: Alex Elder _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs