path: root/kernel/sched.c
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authorJeremy Fitzhardinge <>2007-05-08 00:28:02 -0700
committerLinus Torvalds <>2007-05-08 11:15:06 -0700
commit966812dc98e6a7fcdf759cbfa0efab77500a8868 (patch)
tree47e38e3c866f1855962e212e6e11f2ab656df710 /kernel/sched.c
parent8524070b7982d76258942275908b7434cfcab4b4 (diff)
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 <> Cc: Ingo Molnar <> Cc: Thomas Gleixner <> Cc: john stultz <> Cc: Zachary Amsden <> Cc: James Morris <> Cc: Dan Hecht <> Cc: Paul Mackerras <> Cc: Martin Schwidefsky <> Cc: Prarit Bhargava <> Cc: Chris Lalancette <> Cc: Rick Lindsley <> Cc: Eric Dumazet <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'kernel/sched.c')
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