{"id":807323,"url":"http://patchwork.ozlabs.org/api/patches/807323/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20170829213657.GO27715@localhost.localdomain/","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20170829213657.GO27715@localhost.localdomain>","list_archive_url":null,"date":"2017-08-29T21:36:57","name":"fixup! hostmem-file: Add \"discard-data\" option","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"3f09c9c4dc33df96bf597feb04451b09ef9c7e94","submitter":{"id":195,"url":"http://patchwork.ozlabs.org/api/people/195/?format=json","name":"Eduardo Habkost","email":"ehabkost@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20170829213657.GO27715@localhost.localdomain/mbox/","series":[{"id":485,"url":"http://patchwork.ozlabs.org/api/series/485/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/list/?series=485","date":"2017-08-29T21:36:57","name":"fixup! hostmem-file: Add \"discard-data\" option","version":1,"mbox":"http://patchwork.ozlabs.org/series/485/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/807323/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/807323/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":["ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=nongnu.org\n\t(client-ip=2001:4830:134:3::11; helo=lists.gnu.org;\n\tenvelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org;\n\treceiver=)","ext-mx06.extmail.prod.ext.phx2.redhat.com;\n\tdmarc=none (p=none dis=none) header.from=redhat.com","ext-mx06.extmail.prod.ext.phx2.redhat.com;\n\tspf=fail smtp.mailfrom=ehabkost@redhat.com"],"Received":["from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11])\n\t(using TLSv1 with cipher AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby ozlabs.org (Postfix) with ESMTPS id 3xhhnP08VLz9s2G\n\tfor ;\n\tWed, 30 Aug 2017 07:37:44 +1000 (AEST)","from localhost ([::1]:47115 helo=lists.gnu.org)\n\tby lists.gnu.org with esmtp (Exim 4.71) (envelope-from\n\t)\n\tid 1dmoCa-0005ML-AY\n\tfor incoming@patchwork.ozlabs.org; Tue, 29 Aug 2017 17:37:40 -0400","from eggs.gnu.org ([2001:4830:134:3::10]:33022)\n\tby lists.gnu.org with esmtp (Exim 4.71)\n\t(envelope-from ) id 1dmoC1-0005K3-GH\n\tfor qemu-devel@nongnu.org; Tue, 29 Aug 2017 17:37:06 -0400","from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)\n\t(envelope-from ) id 1dmoBy-0003ep-AP\n\tfor qemu-devel@nongnu.org; Tue, 29 Aug 2017 17:37:05 -0400","from mx1.redhat.com ([209.132.183.28]:41674)\n\tby eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32)\n\t(Exim 4.71) (envelope-from ) id 1dmoBy-0003eD-1K\n\tfor qemu-devel@nongnu.org; Tue, 29 Aug 2017 17:37:02 -0400","from smtp.corp.redhat.com\n\t(int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16])\n\t(using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits))\n\t(No client certificate requested)\n\tby mx1.redhat.com (Postfix) with ESMTPS id B7C25267CA;\n\tTue, 29 Aug 2017 21:37:00 +0000 (UTC)","from localhost (ovpn-116-31.gru2.redhat.com [10.97.116.31])\n\tby smtp.corp.redhat.com (Postfix) with ESMTP id 3648D6A32C;\n\tTue, 29 Aug 2017 21:36:58 +0000 (UTC)"],"DMARC-Filter":"OpenDMARC Filter v1.3.2 mx1.redhat.com B7C25267CA","Date":"Tue, 29 Aug 2017 18:36:57 -0300","From":"Eduardo Habkost ","To":"\"Daniel P. Berrange\" ","Message-ID":"<20170829213657.GO27715@localhost.localdomain>","References":"<20170824192315.5897-1-ehabkost@redhat.com>\n\t<20170824192315.5897-4-ehabkost@redhat.com>\n\t<20170829111345.GI3783@redhat.com>\n\t<20170829131258.GA30734@localhost.localdomain>","MIME-Version":"1.0","Content-Type":"text/plain; charset=us-ascii","Content-Disposition":"inline","In-Reply-To":"<20170829131258.GA30734@localhost.localdomain>","X-Fnord":"you can see the fnord","User-Agent":"Mutt/1.8.0 (2017-02-23)","X-Scanned-By":"MIMEDefang 2.79 on 10.5.11.16","X-Greylist":"Sender IP whitelisted, not delayed by milter-greylist-4.5.16\n\t(mx1.redhat.com [10.5.110.30]);\n\tTue, 29 Aug 2017 21:37:01 +0000 (UTC)","X-detected-operating-system":"by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic]\n\t[fuzzy]","X-Received-From":"209.132.183.28","Subject":"[Qemu-devel] [PATCH] fixup! hostmem-file: Add \"discard-data\" option","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.21","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"Paolo Bonzini ,\n\tZack Cornelius , qemu-devel@nongnu.org,\n\t\"Dr. David Alan Gilbert\" ,\n\tIgor Mammedov ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n\t"},"content":"On Tue, Aug 29, 2017 at 10:12:58AM -0300, Eduardo Habkost wrote:\n> On Tue, Aug 29, 2017 at 12:13:45PM +0100, Daniel P. Berrange wrote:\n> > On Thu, Aug 24, 2017 at 04:23:15PM -0300, Eduardo Habkost wrote:\n[...]\n> > > @@ -4172,6 +4172,9 @@ the path to either a shared memory or huge page filesystem mount.\n> > > The @option{share} boolean option determines whether the memory\n> > > region is marked as private to QEMU, or shared. The latter allows\n> > > a co-operating external process to access the QEMU memory region.\n> > > +Setting the @option{discard-data} boolean option to @var{on}\n> > > +indicates that file contents can be destroyed when QEMU exits,\n> > > +to avoid unnecessarily flushing data to the backing file.\n> > \n> > We should note that this only works if QEMU shuts down normally. If QEMU\n> > is aggressively killed (SIGKILL) or aborts for some reason, then we'll\n> > never get a chance to invoke madvise(), so presumably the kernel will\n> > still flush the data\n> \n> Good point. I tried to not give any guarantees by saying\n> \"contents _can_ be destroyed\", but users may still have different\n> expectations.\n> \n> I will change it to:\n> \n> Setting the @option{discard-data} boolean option to @var{on}\n> indicates that file contents can be destroyed when QEMU exits,\n> to avoid unnecessarily flushing data to the backing file. Note\n> that @option{discard-data} is only an optimization, and QEMU\n> might not discard file contents if it aborts unexpectedly or is\n> terminated using SIGKILL.\n\nFixup patch:\n\nSigned-off-by: Eduardo Habkost \n---\n qemu-options.hx | 5 ++++-\n 1 file changed, 4 insertions(+), 1 deletion(-)","diff":"diff --git a/qemu-options.hx b/qemu-options.hx\nindex ad985e4..de9a18a 100644\n--- a/qemu-options.hx\n+++ b/qemu-options.hx\n@@ -4174,7 +4174,10 @@ region is marked as private to QEMU, or shared. The latter allows\n a co-operating external process to access the QEMU memory region.\n Setting the @option{discard-data} boolean option to @var{on}\n indicates that file contents can be destroyed when QEMU exits,\n-to avoid unnecessarily flushing data to the backing file.\n+to avoid unnecessarily flushing data to the backing file. Note\n+that @option{discard-data} is only an optimization, and QEMU\n+might not discard file contents if it aborts unexpectedly or is\n+terminated using SIGKILL.\n \n @item -object rng-random,id=@var{id},filename=@var{/dev/random}\n \n","prefixes":[]}