Critical bugfixes for the VMI-Timer code.
1) Do not setup a one shot alarm if we are keeping the periodic alarm
armed. Additionally, since the periodic alarm can be run at a lower rate
than HZ, let's fixup the guard to the no-idle-hz mode appropriately. This
fixes the bug where the no-idle-hz mode might have a higher interrupt rate
than the non-idle case.
2) The interrupt handler can no longer adjust xtime due to nested lock
acquisition. Drop this. We don't need to check for wallclock time at
every tick, it can be done in userspace instead.
3) Add a bypass to disable noidle operation. This is useful as a last
minute workaround, or testing measure.
4) The code to skip the IO_APIC timer testing (no_timer_check) should be
conditional on IO_APIC, not SMP, since UP kernels can have this configured
in as well.
Signed-off-by: Dan Hecht <dhecht@vmware.com>
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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