From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 4741890010C for ; Tue, 10 May 2011 10:05:48 -0400 (EDT) From: OGAWA Hirofumi Subject: Re: [PATCHSET v3.1 0/7] data integrity: Stabilize pages during writeback for various fses References: <20110509230318.19566.66202.stgit@elm3c44.beaverton.ibm.com> <87tyd31fkc.fsf@devron.myhome.or.jp> <20110510123819.GB4402@quack.suse.cz> <87hb924s2x.fsf@devron.myhome.or.jp> <20110510132953.GE4402@quack.suse.cz> <878vue4qjb.fsf@devron.myhome.or.jp> Date: Tue, 10 May 2011 23:05:41 +0900 In-Reply-To: <878vue4qjb.fsf@devron.myhome.or.jp> (OGAWA Hirofumi's message of "Tue, 10 May 2011 22:46:16 +0900") Message-ID: <87zkmu3b2i.fsf@devron.myhome.or.jp> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: Jan Kara Cc: "Darrick J. Wong" , Theodore Tso , Alexander Viro , Jens Axboe , "Martin K. Petersen" , Jeff Layton , Dave Chinner , linux-kernel , Dave Hansen , Christoph Hellwig , linux-mm@kvack.org, Chris Mason , Joel Becker , linux-scsi , linux-fsdevel , linux-ext4@vger.kernel.org, Mingming Cao OGAWA Hirofumi writes: > Jan Kara writes: > >>> I see. So many block layer stuff sounds like broken on corner case? If >>> so, I more feel this approach should be temporary workaround, and should >>> use another less-blocking approach. >> Not many but some... The alternative to less blocking approach is to do >> copy-out before a page is submitted for IO (or various middle ground >> alternatives of doing sometimes copyout, sometimes blocking...). That costs >> some performance as well. We talked about it at LSF and the approach >> Darrick is implementing was considered the least intrusive. There's really >> no way to fix these corner cases and keep performance. > > You already considered, to copy only if page was writeback (like > copy-on-write). I.e. if page is on I/O, copy, then switch the page for > writing new data. missed question mark in here. Did you already consider, to copy only if page was writeback (like copy-on-write)? I.e. if page is on I/O, copy, then switch the page for writing new data. > Yes, it is complex. But I think blocking and overhead is minimum, and > this can be used as infrastructure for copy-on-write FS. -- OGAWA Hirofumi -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org