[dpdk-dev] virtio "how to restart applications" - //dpdk.org/doc/virtio-net-pmd
Gopakumar Choorakkot Edakkunni
gopakumar.c.e at gmail.com
Fri Mar 17 05:56:01 CET 2017
Thanks for the confirmation about not having to do anything special to
close the ports on dpdk going down or coming up.
As for the question about if I met any issue of ovs getting stuck - yes, my
guest process runs dpdk 16.07 as I mentioned earlier - and if I kill my
guest process, then the host OVS-dpdk on the host reports stall ! The
OVS-dpdk and emu versions I use are as below. But maybe that is because of
the ovs missing the fixes you mentioned ?
~# ovs-vswitchd --version
ovs-vswitchd (Open vSwitch) 2.4.1
Compiled Nov 14 2016 06:53:31
# kvm --version
QEMU emulator version 2.2.0, Copyright (c) 2003-2008 Fabrice Bellard
On Thu, Mar 16, 2017 at 9:35 PM, Yuanhan Liu <yuanhan.liu at linux.intel.com>
> On Thu, Mar 16, 2017 at 07:48:28PM -0700, Gopakumar Choorakkot Edakkunni
> > Thanks a lot for the response Yuanhan. I am using dpdk v16.07. So what
> you are
> > saying is that in 16.07, we dont really need to call rte_eth_dev_close()
> > exit,
> It's not about "don't really need", it's more like "it's hard to". Just
> think that it may crash at any time.
> > because dpdk will ensure that it will do virtio reset before init when it
> > comes up right ?
> No, It just handles the abnormal case well when guest APP restarts.
> > Regarding the vhost commits you mentioned - do we still need those fixes
> if we
> > have the "virtio reset before init" mechanism ?
> Yes, we still need them: just think some malicious guest may also forge
> data like that.
> I'm a bit confused then. Have you actually met any issue (like got stucked)
> with DPDK v16.07?
> > Or that is a seperate problem
> > altogether (and hence we would need those fixes) ?
> > Rgds,
> > Gopa.
> > On Thu, Mar 16, 2017 at 7:06 PM, Yuanhan Liu <
> yuanhan.liu at linux.intel.com>
> > wrote:
> > On Thu, Mar 16, 2017 at 12:39:16PM -0700, Gopakumar Choorakkot
> > wrote:
> > > So the doc says we should call rte_eth_dev_close() *before* going
> > And I
> > > know that especially in dpdk-virtionet in the guest + ovs-dpdk in
> > host,
> > > the ovs ends up getting stalled/stuck (!!) if I dont close the port
> > before
> > > starting() it when the guest dpdk process comes back up.
> > I'm assuming you were using an old version, something like dpdk v2.2?
> > IIRC, DPDK v16.04 should have fixed your issue.
> > > Considering that this not done properly can screw up the HOST ovs,
> and I
> > want
> > > to do everything possible to avoid that, I want to be 200% sure
> that I
> > call
> > > close even if my process gets a kill -9 .. So obviously the only
> way of
> > doing
> > > that is to close the port when the dpdk process comes back up and
> > *before* we
> > > init the port. rte_eth_dev_close() is not capable of doing that as
> > expects
> > > the port parameters to be initialized etc.. before it can be
> > We do virtio reset before init, which is basically what
> > mainly does. So I see no big issue here.
> > The stuck issue is due to hugepage reset by the guest DPDK
> > leading all virtio vring elements being mem zeroed. The old vhost
> > handle it well, as a result, it got stuck. And here are some relevant
> > commits:
> > a436f53 vhost: avoid dead loop chain
> > c687b0b vhost: check for ring descriptors overflow
> > 623bc47 vhost: do sanity check for ring descriptor length
> > --yliu
> > > Any other
> > > suggestions on what can be done to close on restart rather than
> close on
> > going
> > > down ? Thought of bouncing this by the alias before I add a
> version of
> > close
> > > myself that can do this close-on-restart
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