From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Richard W.M. Jones" Subject: Re: Making discard/fstrim reliable Date: Thu, 3 Apr 2014 19:08:39 +0100 Message-ID: <20140403180839.GR1302@redhat.com> References: <20140326204708.GA29191@redhat.com> <533DA127.5090909@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: =?utf-8?B?THVrw6HFoQ==?= Czerner , linux-fsdevel@vger.kernel.org To: Paolo Bonzini Return-path: Received: from mx1.redhat.com ([209.132.183.28]:21193 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752973AbaDCSIm (ORCPT ); Thu, 3 Apr 2014 14:08:42 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s33I8f7m012180 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 3 Apr 2014 14:08:42 -0400 Content-Disposition: inline In-Reply-To: <533DA127.5090909@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Thu, Apr 03, 2014 at 07:57:59PM +0200, Paolo Bonzini wrote: > From Richard's description, what seems to happen is that ext4 FITRIM > scans the filesystem and prepares the discard requests; but then it > sends them down to the filesystem after the ioctl has finished. > Does that make any sense? And would that be considered a bug? That would account for it if it happened. I'm still working on a good reproducer. It's remarkably hard to reproduce on fast / 64 bit hardware ... Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/