Re: Need help with fixing the Xen waitqueue feature

[Olaf Hering <olaf@aepfle.de>]

On Tue, Nov 22, Keir Fraser wrote:

> I have a new theory, which is that if we go round the for-loop in
> wait_event() more than once, the vcpu's pause counter gets messed up and
> goes negative, condemning it to sleep forever.

I have added a check for that, its not negative.
 
> I have *just* pushed a change to the debug 'q' key (ignore the changeset
> comment referring to 'd' key, I got that wrong!) which will print per-vcpu
> and per-domain pause_count values. Please get the system stuck again, and
> send the output from 'q' key with that new changeset (c/s 24178).

To me it looks like dom0 gets paused, perhaps due to some uneven pause/unpause calls.
I will see if I can figure it out.

Olaf

(XEN) 'q' pressed -> dumping domain info (now=0xA1:4BC733CC)
(XEN) General information for domain 0:
(XEN)     refcnt=3 dying=0 pause_count=0
(XEN)     nr_pages=5991502 xenheap_pages=5 dirty_cpus={} max_pages=4294967295
(XEN)     handle=00000000-0000-0000-0000-000000000000 vm_assist=00000004
(XEN) Rangesets belonging to domain 0:
(XEN)     I/O Ports  { 0-1f, 22-3f, 44-60, 62-9f, a2-3f7, 400-407, 40c-cfb, d00-ffff }
(XEN)     Interrupts { 0-303 }
(XEN)     I/O Memory { 0-febff, fec01-fec8f, fec91-fedff, fee01-ffffffffffffffff }
(XEN) Memory pages belonging to domain 0:
(XEN)     DomPage list too long to display
(XEN)     XenPage 000000000036ff8d: caf=c000000000000002, taf=7400000000000002
(XEN)     XenPage 000000000036ff8c: caf=c000000000000001, taf=7400000000000001
(XEN)     XenPage 000000000036ff8b: caf=c000000000000001, taf=7400000000000001
(XEN)     XenPage 000000000036ff8a: caf=c000000000000001, taf=7400000000000001
(XEN)     XenPage 000000000008befd: caf=c000000000000002, taf=7400000000000002
(XEN) VCPU information and callbacks for domain 0:
(XEN)     VCPU0: CPU0 [has=F] poll=0 upcall_pend = 01, upcall_mask = 00 dirty_cpus={} cpu_affinity={0}
(XEN)     pause_count=1 pause_flags=0
(XEN)     250 Hz periodic timer (period 4 ms)
(XEN) General information for domain 1:
(XEN)     refcnt=3 dying=0 pause_count=0
(XEN)     nr_pages=17549 xenheap_pages=6 dirty_cpus={} max_pages=131328
(XEN)     handle=5499728e-7f38-dbb0-b6cc-22866a6864f3 vm_assist=00000000
(XEN)     paging assistance: hap refcounts translate external
(XEN) Rangesets belonging to domain 1:
(XEN)     I/O Ports  { }
(XEN)     Interrupts { }
(XEN)     I/O Memory { }
(XEN) Memory pages belonging to domain 1:
(XEN)     DomPage list too long to display
(XEN)     PoD entries=0 cachesize=0
(XEN)     XenPage 0000000000200b7c: caf=c000000000000001, taf=7400000000000001
(XEN)     XenPage 0000000000203bfe: caf=c000000000000001, taf=7400000000000001
(XEN)     XenPage 0000000000200b48: caf=c000000000000001, taf=7400000000000001
(XEN)     XenPage 000000000021291d: caf=c000000000000001, taf=7400000000000001
(XEN)     XenPage 000000000003ebfc: caf=c000000000000001, taf=7400000000000001
(XEN)     XenPage 0000000000202ef4: caf=c000000000000001, taf=7400000000000001
(XEN) VCPU information and callbacks for domain 1:
(XEN)     VCPU0: CPU0 [has=F] poll=0 upcall_pend = 00, upcall_mask = 00 dirty_cpus={} cpu_affinity={0}
(XEN)     pause_count=0 pause_flags=4
(XEN)     paging assistance: hap, 4 levels
(XEN)     No periodic timer
(XEN) Notifying guest 0:0 (virq 1, port 0, stat 0/-1/-1)
(XEN) Notifying guest 1:0 (virq 1, port 0, stat 0/0/0)