From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50988) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dvL1i-0005LO-7S for qemu-devel@nongnu.org; Fri, 22 Sep 2017 06:17:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dvL1e-0004xP-TP for qemu-devel@nongnu.org; Fri, 22 Sep 2017 06:17:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40586) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dvL1e-0004wi-KU for qemu-devel@nongnu.org; Fri, 22 Sep 2017 06:17:38 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id BDA67806D1 for ; Fri, 22 Sep 2017 10:17:37 +0000 (UTC) Date: Fri, 22 Sep 2017 11:17:28 +0100 From: "Daniel P. Berrange" Message-ID: <20170922101728.GJ12725@redhat.com> Reply-To: "Daniel P. Berrange" References: <1506070572-7549-1-git-send-email-peterx@redhat.com> <1506070572-7549-2-git-send-email-peterx@redhat.com> <20170922090433.GC12725@redhat.com> <20170922091430.GJ30661@pxdev.xzpeter.org> <20170922093631.GG12725@redhat.com> <4760b1a1-446d-fc2c-8794-8860bededc56@redhat.com> <20170922094325.GH12725@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH 1/3] iothread: provide helpers for internal use List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Peter Xu , qemu-devel@nongnu.org, Stefan Hajnoczi , Fam Zheng , "Dr . David Alan Gilbert" On Fri, Sep 22, 2017 at 12:14:04PM +0200, Paolo Bonzini wrote: > On 22/09/2017 11:43, Daniel P. Berrange wrote: > > On Fri, Sep 22, 2017 at 11:38:31AM +0200, Paolo Bonzini wrote: > >> On 22/09/2017 11:36, Daniel P. Berrange wrote: > >>> On Fri, Sep 22, 2017 at 05:14:30PM +0800, Peter Xu wrote: > >>>> On Fri, Sep 22, 2017 at 10:04:33AM +0100, Daniel P. Berrange wrote: > >>>>> On Fri, Sep 22, 2017 at 04:56:10PM +0800, Peter Xu wrote: > >>>>>> IOThread is a general framework that contains IO loop environment and a > >>>>>> real thread behind. It's also good to be used internally inside qemu. > >>>>>> Provide some helpers for it to create iothreads to be used internally. > >>>>>> > >>>>>> Signed-off-by: Peter Xu > >>>>>> --- > >>>>>> include/sysemu/iothread.h | 8 ++++++++ > >>>>>> iothread.c | 21 +++++++++++++++++++++ > >>>>>> 2 files changed, 29 insertions(+) > >>>>>> > >>>>>> diff --git a/include/sysemu/iothread.h b/include/sysemu/iothread.h > >>>>>> index d2985b3..b07663f 100644 > >>>>>> --- a/include/sysemu/iothread.h > >>>>>> +++ b/include/sysemu/iothread.h > >>>>>> @@ -46,4 +46,12 @@ AioContext *iothread_get_aio_context(IOThread *iothread); > >>>>>> void iothread_stop_all(void); > >>>>>> GMainContext *iothread_get_g_main_context(IOThread *iothread); > >>>>>> > >>>>>> +/* > >>>>>> + * Helpers used to allocate iothreads for internal use. These > >>>>>> + * iothreads will not be seen by monitor clients when query using > >>>>>> + * "query-iothreads". > >>>>>> + */ > >>>>>> +IOThread *iothread_create(const char *id, Error **errp); > >>>>>> +void iothread_destroy(IOThread *iothread); > >>>>>> + > >>>>>> #endif /* IOTHREAD_H */ > >>>>>> diff --git a/iothread.c b/iothread.c > >>>>>> index 44c8944..74e400c 100644 > >>>>>> --- a/iothread.c > >>>>>> +++ b/iothread.c > >>>>>> @@ -354,3 +354,24 @@ GMainContext *iothread_get_g_main_context(IOThread *iothread) > >>>>>> > >>>>>> return iothread->worker_context; > >>>>>> } > >>>>>> + > >>>>>> +static Object *iothread_get_internal_parent(void) > >>>>>> +{ > >>>>>> + return container_get(object_get_root(), "/internal-iothreads"); > >>>>>> +} > >>>>> > >>>>> I tend to think we might benefit from having this generalized in the > >>>>> QOM API instead. We have object_get_objects_root() for things that > >>>>> are created by the mgmt app / user via CLI / QMP. A parallel method > >>>>> object_get_internal_root() could be useful for cases like this where > >>>>> we want to create user-creatable objects, but not have them be > >>>>> visible to the mgmt app / user, as that would confuse the mgmt app. > >>>>> > >>>>> Example for this scenario - libvirt calls query-iothreads to identify > >>>>> IO thread PIDs, and would get very unhappy if the IOThread used by > >>>>> the monitor would appear in that response, which is why Peter has > >>>>> put it under /internal-iothreads. I think this scenario will apply > >>>>> more broadly, so benefit from us having a general helper in QOM. > >>>> > >>>> Yeah, I can split the patch if we want it to be exposed to public. > >>>> > >>>> In that case, would the name "object_get_internal_root" be good? > >>> > >>> Yeah that's fine with me, but lets see if Paolo has any thoughts from > >>> the QOM side. > >> > >> No, I don't. However, I wonder if query-iothreads should have an > >> argument to include internal iothreads. > > > > I guess it depends whether we consider use of iothreads for migration > > to be a private impl detail that may be ripped out & replaced at any > > time, or a semi-public detail that apps may rely on. Personally I > > would suggest it should be a private impl detail of migration code > > that is never exposed to anything outside QEMU, so we have flexibility > > to change it at will later. > > As far as I understood it's not migration, it's the whole monitor that > moves to the iothread. So it's a thing that lasts for the whole > existence of the QEMU process. But I may be wrong. Sorry yes, my bad - its the iothread behind the monitor. I still think that is a detail worth keeping private in case we want to refactor how the monitor threading works later. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|