[ovs-discuss] ovs-ofctl fails occasionally
Ben Pfaff
blp at ovn.org
Fri Mar 1 19:00:55 UTC 2019
Thanks, I applied this to master and backported it as far as it would go.
On Fri, Mar 01, 2019 at 04:45:22AM +0000, Ken Ajiro wrote:
>
> Ben,
>
> > The following stopgap appears to fix the problem on master. I suspect
> > it could be easily backported as far as necessary. Does it work for you
> > too?
>
> Yes, it worked. Thank you for your support.
>
> Thanks,
> Ken
>
> On Thu, 28 Feb 2019 00:12:54 +0000,
> blp at ovn.org wrote
> in E-mail "Re: [ovs-discuss] ovs-ofctl fails occasionally":
>
> > On Wed, Feb 27, 2019 at 12:45:58PM +0000, Ken Ajiro wrote:
> > >
> > > Hello,
> > >
> > > When I use ovs-ofctl on OVS 2.10.1, it failed occasionally by error:
> > >
> > > ovs-ofctl: br0: failed to connect to socket (Broken pipe)
> > >
> > > This error is possible to be reproduced with:
> > >
> > > # while :; do /opt/nec/pf/ds/bin/ovs-ofctl --timeout=5 dump-flows br0 > /tmp/log || break; done; cat /tmp/log
> > > ovs-ofctl: br0: failed to connect to socket (Broken pipe)
> > >
> > > Also I tried with OVS 2.4.1 and could not reproduce this error.
> > >
> > > I think that recently rconn.c was modified on commit 476d2551abd2871696a64203f78d658ac2d7f32c
> > > and the connection for ofctl was changed it begins on state S_CONNECTING instead of S_ACTIVE.
> > > So timeout_CONNECTING will be applied for ofctl connection, however timeout_CONNECTING is 1
> > > and this is too short (e.g. if transition time of CONNCTING was 12:00:00.999, it will be timed out
> > > after 1ms). I think that this is cause of occasionally disconnection of ofctl.
> >
> > Thanks for the report.
> >
> > It seems to me that the right long-term fix is to use higher resolution
> > (e.g. millisecond resolution) to measure the timeouts. However, that
> > will be a relatively large fix.
> >
> > The following stopgap appears to fix the problem on master. I suspect
> > it could be easily backported as far as necessary. Does it work for you
> > too?
> >
> > diff --git a/lib/rconn.c b/lib/rconn.c
> > index 48ae8c6a72e5..8ca23cbcfe90 100644
> > --- a/lib/rconn.c
> > +++ b/lib/rconn.c
> > @@ -502,7 +502,7 @@ static unsigned int
> > timeout_CONNECTING(const struct rconn *rc)
> > OVS_REQUIRES(rc->mutex)
> > {
> > - return MAX(1, rc->backoff);
> > + return MAX(2, rc->backoff);
> > }
> >
> > static void
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