Migration with "--p2p --tunnelled" hanging in v6.9.0

Christian Ehrhardt christian.ehrhardt at canonical.com
Thu Nov 26 09:02:29 UTC 2020


On Wed, Nov 25, 2020 at 7:06 PM Daniel P. Berrangé <berrange at redhat.com> wrote:
>
> On Wed, Nov 25, 2020 at 05:20:41PM +0000, Daniel P. Berrangé wrote:
> > On Wed, Nov 25, 2020 at 05:00:20PM +0000, Daniel P. Berrangé wrote:
> > > On Wed, Nov 25, 2020 at 04:36:39PM +0000, Daniel P. Berrangé wrote:
> > > > On Wed, Nov 25, 2020 at 04:49:14PM +0100, Christian Ehrhardt wrote:
> > > > > I found that the same vol-download vs 127.0.0.1 gives the same results.
> > > > > That in turn makes it easier to gather results as we only need one system.
> > > >
> > > > Yep, that's useful, I'm able to reproduce this problem myself too
> > > > now. Will do some local tests and report back...
> > >
> > > Sigh, the problem is way too many reallocs, repeatedly growing and shrinking
> > > the buffer we use for I/O.
> > >
> > > I guess we never noticed this awfulness in the virsh console code it was
> > > copied from, as the data volumes are lower.
> > >
> > > Switching to a fixed size buffer makes it massively faster. I'll prep a
> > > patch asap.
> >
> > Actually, it is also important to have a bigger buffer. Using a 1 MB buffer
> > makes all the difference in throughput.
>
> I've sent two patches to improve the performance and managed to test
> vol-download with our ssh helper to beat netcat. I've not had a chance
> to test with tunnelled migration yet though, so if you want to try the
> patches with your migration test scenario, that'd be useful confirmation

Thank you Daniel,
I've done extensive testing (all good) and replied with details and a
Tested-by to the patch submission.

>
> Regards,
> Daniel
> --
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>


-- 
Christian Ehrhardt
Staff Engineer, Ubuntu Server
Canonical Ltd





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