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Re: [Qemu-devel] test-filter-mirror hangs
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] test-filter-mirror hangs |
Date: |
Wed, 23 Jan 2019 19:53:46 +0000 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
* Jason Wang (address@hidden) wrote:
>
> On 2019/1/22 上午2:56, Peter Maydell wrote:
> > On Thu, 17 Jan 2019 at 09:46, Jason Wang <address@hidden> wrote:
> > >
> > > On 2019/1/15 上午12:33, Zhang Chen wrote:
> > > >
> > > > On Sat, Jan 12, 2019 at 12:15 AM Dr. David Alan Gilbert
> > > > <address@hidden <mailto:address@hidden>> wrote:
> > > >
> > > > * Peter Maydell (address@hidden
> > > > <mailto:address@hidden>) wrote:
> > > > > Recently I've noticed that test-filter-mirror has been hanging
> > > > > intermittently, typically when run on some other TCG
> > > > architecture.
> > > > > In the instance I've just looked at, this was with s390x guest on
> > > > > x86-64 host, though I've also seen it on other host archs and
> > > > > perhaps with other guests.
> > > >
> > > > Watch out to see if you really do see it for other guests;
> > > > it carefully avoids using virtio-net to avoid vhost; but on s390x
> > > > it
> > > > uses virtio-net-ccw - could that hit the vhost it was trying to
> > > > avoid?
> > > >
> > > > > Below is a backtrace, though it seems to be pretty unhelpful.
> > > > > Anybody got any theories ? Does the mirror test rely on dirty
> > > > > memory bitmaps like the migration test (which also hangs
> > > > > occasionally with TCG due to some bug I'm sure we've investigated
> > > > > in the past) ?
> > > >
> > > > I don't think it relies on the CPU at all.
> > > > I have no idea about this currently, but Jason and I designed the
> > > > test case.
> > > > Add Jason: Have any comments about this ?
> > >
> > > I can't reproduce this locally with s390x-softmmu. It looks to me the
> > > test should be independent to any kinds of emulation. It should pass
> > > when mainloop work.
> > I've just seen a hang with ppc64 guest on s390x host, so it is
> > indeed not specific to s390x guest (and so not specific to
> > virtio-net either, since the ppc64 guest setup uses e1000).
> >
> > thanks
> > -- PMM
>
>
> Finally reproduced locally after hundreds (sometimes thousands) times of
> running.
>
> Bisection points to OOB monitor[1].
>
> It looks to me after OOB is used unconditionally we lose a barrier to make
> sure socket is connected before sending packets in test-filter-mirror.c. Is
> there any other similar and simple thing that we could do to kick the
> mainloop?
Do you mean the:
/* send a qmp command to guarantee that 'connected' is setting to true. */
qmp_discard_response(qts, "{ 'execute' : 'query-status'}");
why was that ever sufficient to know the socket was ready?
Dave
> Thanks
>
> [1]
>
> commit 8258292e18c39480b64eba9f3551ab772ce29b5d (HEAD, refs/bisect/bad)
> Author: Peter Xu <address@hidden>
> Date: Tue Oct 9 14:27:15 2018 +0800
>
> monitor: Remove "x-oob", offer capability "oob" unconditionally
>
> Out-of-band command execution was introduced in commit cf869d53172.
> Unfortunately, we ran into a regression, and had to turn it into an
> experimental option for 2.12 (commit be933ffc23).
>
> http://lists.gnu.org/archive/html/qemu-devel/2018-03/msg06231.html
>
> The regression has since been fixed (commit 951702f39c7 "monitor: bind
> dispatch bh to iohandler context"). A thorough re-review of OOB
> commands led to a few more issues, which have also been addressed.
>
> This patch partly reverts be933ffc23 (monitor: new parameter "x-oob"),
> and makes QMP monitors again offer capability "oob" whenever they can
> provide it, i.e. when the monitor's character device is capable of
> running in an I/O thread.
>
> Some trivial touch-up in the test code is required to make sure qmp-test
> won't break.
>
> Reviewed-by: Markus Armbruster <address@hidden>
> Reviewed-by: Marc-André Lureau <address@hidden>
> Signed-off-by: Peter Xu <address@hidden>
> Message-Id: <address@hidden>
> [Conflict with "monitor: check if chardev can switch gcontext for OOB"
> resolved, commit message updated]
> Signed-off-by: Markus Armbruster <address@hidden>
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] test-filter-mirror hangs, Peter Maydell, 2019/01/11
- Re: [Qemu-devel] test-filter-mirror hangs, Dr. David Alan Gilbert, 2019/01/11
- Re: [Qemu-devel] test-filter-mirror hangs, Zhang Chen, 2019/01/14
- Re: [Qemu-devel] test-filter-mirror hangs, Jason Wang, 2019/01/22
- Re: [Qemu-devel] test-filter-mirror hangs,
Dr. David Alan Gilbert <=
- Re: [Qemu-devel] test-filter-mirror hangs, Jason Wang, 2019/01/23
- Re: [Qemu-devel] test-filter-mirror hangs, Dr. David Alan Gilbert, 2019/01/24
- Re: [Qemu-devel] test-filter-mirror hangs, Peter Xu, 2019/01/24
- Re: [Qemu-devel] test-filter-mirror hangs, Jason Wang, 2019/01/24
- Re: [Qemu-devel] test-filter-mirror hangs, Markus Armbruster, 2019/01/25
- Re: [Qemu-devel] test-filter-mirror hangs, Jason Wang, 2019/01/24
- Re: [Qemu-devel] test-filter-mirror hangs, Markus Armbruster, 2019/01/24
- Re: [Qemu-devel] test-filter-mirror hangs, Jason Wang, 2019/01/24
- Re: [Qemu-devel] test-filter-mirror hangs, Markus Armbruster, 2019/01/25
- Re: [Qemu-devel] test-filter-mirror hangs, Jason Wang, 2019/01/25