Re: [Xen-devel] Xen4.2 S3 regression?

[Ben Guthro <ben@xxxxxxxxxx>]

I did some more bisecting here, and I came up with another changeset
that seems to be problematic, Re: IRQs

After bisecting the problem discussed earlier in this thread to the
changeset below,
http://xenbits.xen.org/hg/xen-unstable.hg/rev/0695a5cdcb42


I worked past that issue by the following hack:

--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -1103,7 +1103,7 @@ void evtchn_destroy_final(struct domain *d)
 void evtchn_move_pirqs(struct vcpu *v)
 {
     struct domain *d = v->domain;
-    const cpumask_t *mask = cpumask_of(v->processor);
+    //const cpumask_t *mask = cpumask_of(v->processor);
     unsigned int port;
     struct evtchn *chn;

@@ -1111,7 +1111,9 @@ void evtchn_move_pirqs(struct vcpu *v)
     for ( port = v->pirq_evtchn_head; port; port = chn->u.pirq.next_port )
     {
         chn = evtchn_from_port(d, port);
+#if 0
         pirq_set_affinity(d, chn->u.pirq.irq, mask);
+#endif
     }
     spin_unlock(&d->event_lock);
 }


This seemed to work for this rather old changeset, but it was not
sufficient to fix it against the 4.1, or unstable trees.

I further bisected, in combination with this hack, and found the
following changeset to also be problematic:

http://xenbits.xen.org/hg/xen-unstable.hg/rev/c2cb776a5365


That is, before this change I could resume reliably (with the hack
above) - and after I could not.
This was surprising to me, as this change also looks rather innocuous.


Naturally, backing out this change seems to be non-trivial against the
tip, since so much around it has changed.




On Fri, Aug 17, 2012 at 6:40 AM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>> On 17.08.12 at 12:22, Ben Guthro <ben@xxxxxxxxxx> wrote:
>> On Thu, Aug 16, 2012 at 7:56 AM, Ben Guthro <ben@xxxxxxxxxx> wrote:
>>> In order to not flood the list with large logs, I put the logs here:
>>> https://citrix.sharefile.com/d/sfab699024a54df39
>>> I wasn't sure if you wanted a log with, or without the calls to
>>> evtchn_move_pirqs() commented out - so I included both.
>>
>> I received notifications that this got downloaded yesterday by a couple
>> people.
>> Did you have an opportunity to review it?
>
> Yes, I did.
>
>> If so - did you glean any new knowledge?
>
> Unfortunately not. Instead I was surprised that there were no
> IRQ fixup related messages at all, of which I still will need to
> make sense.
>
> In any case, I'm planning on putting together a debugging patch,
> but can't immediately tell when this will be.
>
> Jan
>

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