From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from www.humilis.net ([82.95.169.224]:34549 "EHLO panda.humilis.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751132Ab2LQKg1 (ORCPT ); Mon, 17 Dec 2012 05:36:27 -0500 Date: Mon, 17 Dec 2012 11:36:24 +0100 From: Sander To: Sylvain Alain Cc: linux-btrfs@vger.kernel.org Subject: Re: btrfs subvolume snapshot performance problem Message-ID: <20121217103624.GA15304@panda> Reply-To: sander@humilis.net References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-btrfs-owner@vger.kernel.org List-ID: Sylvain Alain wrote (ao): > gentootux ~ # mount /dev/sda4 -o > noatime,ssd,discard,compress=lzo,noacl,space_cache,subvolid=0 ^^^^^^^ > Instead of 3 secondes to run the snapshot, it took almost 4 minutes. Let me repeat the answer cwillu gave to Russell on this, and Russell's response: Russell Coker wrote (ao): > On Sun, 16 Dec 2012, cwillu wrote: > > Don't use discard; it's a non-queuing command, which means your > > performance will suck unless your device is really terrible at > > garbage collection (in which case, it's just the lesser of two evils). > > Thanks for the advice. On one of my systems a reinstall of the linux- > image-3.6-trunk-amd64 package went from almost 4 minutes to only 29 > seconds when I removed the discard option.