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Commit 32d62510 authored by Waiman Long's avatar Waiman Long Committed by Ingo Molnar
Browse files

locking/pvqspinlock: Enable slowpath locking count tracking 



This patch enables the tracking of the number of slowpath locking
operations performed. This can be used to compare against the number
of lock stealing operations to see what percentage of locks are stolen
versus acquired via the regular slowpath.

Signed-off-by: default avatarWaiman Long <Waiman.Long@hpe.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Douglas Hatch <doug.hatch@hpe.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
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/1449778666-13593-2-git-send-email-Waiman.Long@hpe.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent cb037fda

kernel/locking/qspinlock_paravirt.h

+5 −0
Original line number Diff line number Diff line
@@ -400,6 +400,11 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node) 
	if (READ_ONCE(pn->state) == vcpu_hashed)

		lp = (struct qspinlock **)1;



	/*

	 * Tracking # of slowpath locking operations

	 */

	qstat_inc(qstat_pv_lock_slowpath, true);



	for (;; waitcnt++) {

		/*

		 * Set correct vCPU state to be used by queue node wait-early

kernel/locking/qspinlock_stat.h

+3 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
 *   pv_kick_wake	- # of vCPU kicks used for computing pv_latency_wake

 *   pv_latency_kick	- average latency (ns) of vCPU kick operation

 *   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
@@ -45,6 +46,7 @@ enum qlock_stats { 
	qstat_pv_kick_wake,

	qstat_pv_latency_kick,

	qstat_pv_latency_wake,

	qstat_pv_lock_slowpath,

	qstat_pv_lock_stealing,

	qstat_pv_spurious_wakeup,

	qstat_pv_wait_again,
@@ -70,6 +72,7 @@ static const char * const qstat_names[qstat_num + 1] = { 
	[qstat_pv_spurious_wakeup] = "pv_spurious_wakeup",

	[qstat_pv_latency_kick]	   = "pv_latency_kick",

	[qstat_pv_latency_wake]    = "pv_latency_wake",

	[qstat_pv_lock_slowpath]   = "pv_lock_slowpath",

	[qstat_pv_lock_stealing]   = "pv_lock_stealing",

	[qstat_pv_wait_again]      = "pv_wait_again",

	[qstat_pv_wait_early]      = "pv_wait_early",