From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:52534) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1glflK-0002P1-SV for qemu-devel@nongnu.org; Mon, 21 Jan 2019 15:01:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1glflH-0000PZ-0a for qemu-devel@nongnu.org; Mon, 21 Jan 2019 15:01:36 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54344) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1glflA-0000IQ-Ha for qemu-devel@nongnu.org; Mon, 21 Jan 2019 15:01:30 -0500 Date: Mon, 21 Jan 2019 20:01:21 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20190121200121.GD2083@work-vm> References: <20190111161515.GG2738@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] test-filter-mirror hangs List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: Jason Wang , Zhang Chen , QEMU Developers , Li Zhijian , Paolo Bonzini * Peter Maydell (peter.maydell@linaro.org) wrote: > On Thu, 17 Jan 2019 at 09:46, Jason Wang wrote: > > > > > > On 2019/1/15 =E4=B8=8A=E5=8D=8812:33, Zhang Chen wrote: > > > > > > > > > On Sat, Jan 12, 2019 at 12:15 AM Dr. David Alan Gilbert > > > > wrote: > > > > > > * Peter Maydell (peter.maydell@linaro.org > > > ) wrote: > > > > Recently I've noticed that test-filter-mirror has been hangin= g > > > > intermittently, typically when run on some other TCG architec= ture. > > > > In the instance I've just looked at, this was with s390x gues= t 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 s39= 0x 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 investig= ated > > > > in the past) ? > > > > > > I don't think it relies on the CPU at all. >=20 > > > 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. >=20 > 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). Hmph, there goes that idea. I guess we need some tracing of the packet flow; do you build with tracing on and can we enable it for a test? Dave > thanks > -- PMM -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK