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authorWaiman Long <Waiman.Long@hpe.com>2016-05-31 18:53:47 +0200
committerIngo Molnar <mingo@kernel.org>2016-08-10 14:16:02 +0200
commit08be8f63c40c030b5cf95b4368e314e563a86301 (patch)
tree79a14559d31108b7e9ad0c559c0070a39f146223 /kernel/locking/qspinlock_stat.h
parentlocking/qspinlock: Improve readability (diff)
downloadlinux-08be8f63c40c030b5cf95b4368e314e563a86301.tar.xz
linux-08be8f63c40c030b5cf95b4368e314e563a86301.zip
locking/pvstat: Separate wait_again and spurious wakeup stats
Currently there are overlap in the pvqspinlock wait_again and spurious_wakeup stat counters. Because of lock stealing, it is no longer possible to accurately determine if spurious wakeup has happened in the queue head. As they track both the queue node and queue head status, it is also hard to tell how many of those comes from the queue head and how many from the queue node. This patch changes the accounting rules so that spurious wakeup is only tracked in the queue node. The wait_again count, however, is only tracked in the queue head when the vCPU failed to acquire the lock after a vCPU kick. This should give a much better indication of the wait-kick dynamics in the queue node and the queue head. Signed-off-by: Waiman Long <Waiman.Long@hpe.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Douglas Hatch <doug.hatch@hpe.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Pan Xinhui <xinhui@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Scott J Norton <scott.norton@hpe.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1464713631-1066-2-git-send-email-Waiman.Long@hpe.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/locking/qspinlock_stat.h')
-rw-r--r--kernel/locking/qspinlock_stat.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h
index b9d031516254..eb0a599fcf58 100644
--- a/kernel/locking/qspinlock_stat.h
+++ b/kernel/locking/qspinlock_stat.h
@@ -24,8 +24,8 @@
* pv_latency_wake - average latency (ns) from vCPU kick to wakeup
* pv_lock_slowpath - # of locking operations via the slowpath
* pv_lock_stealing - # of lock stealing operations
- * pv_spurious_wakeup - # of spurious wakeups
- * pv_wait_again - # of vCPU wait's that happened after a vCPU kick
+ * pv_spurious_wakeup - # of spurious wakeups in non-head vCPUs
+ * pv_wait_again - # of wait's after a queue head vCPU kick
* pv_wait_early - # of early vCPU wait's
* pv_wait_head - # of vCPU wait's at the queue head
* pv_wait_node - # of vCPU wait's at a non-head queue node