On Tue, 2015-10-27 at 16:47 +0100, Samuel Thibault wrote:
> Wei Liu, le Tue 27 Oct 2015 15:43:29 +0000, a écrit :
> > Oxenstored has a behaviour that it only writes a contiguous piece of
> > data. When it writes across ring boundary it will return a short-write
> > while there is still room. That leads to mini-os stalling when it sees
> > there is not enough data in the ring.
> >
> > Given that oxenstored is the default xenstored implementation we think
> > it would be useful to workaround this for the benefit of running mini-
> > os
> > (and unikernel based on it) on any Xen installation.
> >
> > Signed-off-by: Wei Liu <wei.l...@citrix.com>
>
> As discussed in the previous thread, this is rather a workaround.
Given that I'm in the process of applying "tools/ocaml/xb: Correct
calculations of data/space the ring" which I think is the real fix here am
unsure if we still want to take this workaround.
Any thoughts?
> Better
> be safe than sorry.
>
> Acked-by: Samuel Thibault <samuel.thiba...@ens-lyon.org>
>
> And could too be backported to stable branches.
>
> > ---
> > xenbus/xenbus.c | 10 ++++++++--
> > 1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/xenbus/xenbus.c b/xenbus/xenbus.c
> > index 0ab387a..abf8b1b 100644
> > --- a/xenbus/xenbus.c
> > +++ b/xenbus/xenbus.c
> > @@ -205,8 +205,11 @@ static void xenbus_thread_func(void *ign)
> > prod = xenstore_buf->rsp_prod;
> > DEBUG("Rsp_cons %d, rsp_prod %d.\n", xenstore_buf-
> > >rsp_cons,
> > xenstore_buf->rsp_prod);
> > - if (xenstore_buf->rsp_prod - xenstore_buf->rsp_cons <
> > sizeof(msg))
> > + if (xenstore_buf->rsp_prod - xenstore_buf->rsp_cons <
> > sizeof(msg)) {
> > + /* Work around oxenstored bug */
> > + notify_remote_via_evtchn(start_info.store_evtchn);
> > break;
> > + }
> > rmb();
> > memcpy_from_ring(xenstore_buf->rsp,
> > &msg,
> > @@ -217,8 +220,11 @@ static void xenbus_thread_func(void *ign)
> > xenstore_buf->rsp_prod - xenstore_buf->rsp_cons,
> > msg.req_id);
> > if (xenstore_buf->rsp_prod - xenstore_buf->rsp_cons <
> > - sizeof(msg) + msg.len)
> > + sizeof(msg) + msg.len) {
> > + /* Work around oxenstored bug */
> > + notify_remote_via_evtchn(start_info.store_evtchn);
> > break;
> > + }
> >
> > DEBUG("Message is good.\n");
> >
> > --
> > 2.1.4
> >
>
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