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locking/pvqspinlock: Don't wait if vCPU is preempted 

If prev node is not in running state or its vCPU is preempted, we can give
up our vCPU slices in pv_wait_node() ASAP.

Signed-off-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: longman@redhat.com
Link: http://lkml.kernel.org/r/1484035006-6787-1-git-send-email-xinhui.pan@linux.vnet.ibm.com
[ Fixed typos in the changelog, removed ugly linebreak from the code. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Pan Xinhui 2017-01-10 02:56:46 -05:00 committed by Ingo Molnar
parent 607904c357
commit 75437bb304
1 changed files with 1 additions and 1 deletions
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2
kernel/locking/qspinlock_paravirt.h
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@ -263,7 +263,7 @@ pv_wait_early(struct pv_node *prev, int loop)
if ((loop & PV_PREV_CHECK_MASK) != 0)
return false;
return READ_ONCE(prev->state) != vcpu_running;
return READ_ONCE(prev->state) != vcpu_running || vcpu_is_preempted(prev->cpu);
}
/*