From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:56257 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753489AbaDUWN0 (ORCPT ); Mon, 21 Apr 2014 18:13:26 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1WcMSq-0004xf-OT for linux-btrfs@vger.kernel.org; Tue, 22 Apr 2014 00:13:24 +0200 Received: from ip68-231-22-224.ph.ph.cox.net ([68.231.22.224]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 22 Apr 2014 00:13:24 +0200 Received: from 1i5t5.duncan by ip68-231-22-224.ph.ph.cox.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 22 Apr 2014 00:13:24 +0200 To: linux-btrfs@vger.kernel.org From: Duncan <1i5t5.duncan@cox.net> Subject: Re: Snapshot aware defrag and qgroups thoughts Date: Mon, 21 Apr 2014 22:13:11 +0000 (UTC) Message-ID: References: <53553172.9030309@fb.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: Josef Bacik posted on Mon, 21 Apr 2014 07:55:46 -0700 as excerpted: [Near the bottom, point #4 immediately before conclusion.] > You still have to post-process merge to make sure, but you are far more > likely to merge everything in real-time since you are only changing the > sequence number every once and a while instead of for every new sequence > number. Much of this is above my head, which is OK as I'm not a btrfs dev, but... ...only changing the sequence number... for every new sequence number? Something's wrong with that. No WONDER the system live-locked! =:^) My above-my-head guess is that in place of for every new sequence number there, you meant for every delayed ref. Meanwhile, thanks for putting this all down. I already said I don't understand much of it, but I certainly have a better appreciation for the complexities of snapshot-aware-defrag. I hadn't considered what qgroups could do to it at all! -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman