Ignore stolen time in the softlockup watchdog

The softlockup watchdog is currently a nuisance in a virtual machine, since
the whole system could have the CPU stolen from it for a long period of
time.  While it would be unlikely for a guest domain to be denied timer
interrupts for over 10s, it could happen and any softlockup message would
be completely spurious.

Earlier I proposed that sched_clock() return time in unstolen nanoseconds,
which is how Xen and VMI currently implement it.  If the softlockup
watchdog uses sched_clock() to measure time, it would automatically ignore
stolen time, and therefore only report when the guest itself locked up.
When running native, sched_clock() returns real-time nanoseconds, so the
behaviour would be unchanged.

Note that sched_clock() used this way is inherently per-cpu, so this patch
makes sure that the per-processor watchdog thread initialized its own
timestamp.

Signed-off-by: Jeremy Fitzhardinge <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: john stultz <[email protected]>
Cc: Zachary Amsden <[email protected]>
Cc: James Morris <[email protected]>
Cc: Dan Hecht <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Prarit Bhargava <[email protected]>
Cc: Chris Lalancette <[email protected]>
Cc: Rick Lindsley <[email protected]>
Cc: Eric Dumazet <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions