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From: Will Deacon <will.deacon@arm.com>
To: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org, peterz@infradead.org,
	mingo@kernel.org, boqun.feng@gmail.com,
	paulmck@linux.vnet.ibm.com, longman@redhat.com,
	will.deacon@arm.com
Subject: [PATCH v3 13/14] locking/qspinlock: Add stat tracking for pending vs slowpath
Date: Thu, 26 Apr 2018 11:34:27 +0100	[thread overview]
Message-ID: <1524738868-31318-14-git-send-email-will.deacon@arm.com> (raw)
In-Reply-To: <1524738868-31318-1-git-send-email-will.deacon@arm.com>

From: Waiman Long <longman@redhat.com>

Currently, the qspinlock_stat code tracks only statistical counts in the
PV qspinlock code. However, it may also be useful to track the number
of locking operations done via the pending code vs. the MCS lock queue
slowpath for the non-PV case.

The qspinlock stat code is modified to do that. The stat counter
pv_lock_slowpath is renamed to lock_slowpath so that it can be used by
both the PV and non-PV cases.

Signed-off-by: Waiman Long <longman@redhat.com>
---
 kernel/locking/qspinlock.c          | 14 +++++++++++---
 kernel/locking/qspinlock_paravirt.h |  7 +------
 kernel/locking/qspinlock_stat.h     |  9 ++++++---
 3 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 1e3ddc42135e..b39f341d831b 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -12,11 +12,11 @@
  * GNU General Public License for more details.
  *
  * (C) Copyright 2013-2015 Hewlett-Packard Development Company, L.P.
- * (C) Copyright 2013-2014 Red Hat, Inc.
+ * (C) Copyright 2013-2014,2018 Red Hat, Inc.
  * (C) Copyright 2015 Intel Corp.
  * (C) Copyright 2015 Hewlett-Packard Enterprise Development LP
  *
- * Authors: Waiman Long <waiman.long@hpe.com>
+ * Authors: Waiman Long <longman@redhat.com>
  *          Peter Zijlstra <peterz@infradead.org>
  */
 
@@ -33,6 +33,11 @@
 #include <asm/qspinlock.h>
 
 /*
+ * Include queued spinlock statistics code
+ */
+#include "qspinlock_stat.h"
+
+/*
  * The basic principle of a queue-based spinlock can best be understood
  * by studying a classic queue-based spinlock implementation called the
  * MCS lock. The paper below provides a good description for this kind
@@ -295,7 +300,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
 	BUILD_BUG_ON(CONFIG_NR_CPUS >= (1U << _Q_TAIL_CPU_BITS));
 
 	if (pv_enabled())
-		goto queue;
+		goto pv_queue;
 
 	if (virt_spin_lock(lock))
 		return;
@@ -348,6 +353,7 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
 		 * *,1,0 -> *,0,1
 		 */
 		clear_pending_set_locked(lock);
+		qstat_inc(qstat_lock_pending, true);
 		return;
 	}
 
@@ -363,6 +369,8 @@ void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
 	 * queuing.
 	 */
 queue:
+	qstat_inc(qstat_lock_slowpath, true);
+pv_queue:
 	node = this_cpu_ptr(&mcs_nodes[0]);
 	idx = node->count++;
 	tail = encode_tail(smp_processor_id(), idx);
diff --git a/kernel/locking/qspinlock_paravirt.h b/kernel/locking/qspinlock_paravirt.h
index 2dbad2f25480..25730b2ac022 100644
--- a/kernel/locking/qspinlock_paravirt.h
+++ b/kernel/locking/qspinlock_paravirt.h
@@ -56,11 +56,6 @@ struct pv_node {
 };
 
 /*
- * Include queued spinlock statistics code
- */
-#include "qspinlock_stat.h"
-
-/*
  * Hybrid PV queued/unfair lock
  *
  * By replacing the regular queued_spin_trylock() with the function below,
@@ -428,7 +423,7 @@ pv_wait_head_or_lock(struct qspinlock *lock, struct mcs_spinlock *node)
 	/*
 	 * Tracking # of slowpath locking operations
 	 */
-	qstat_inc(qstat_pv_lock_slowpath, true);
+	qstat_inc(qstat_lock_slowpath, true);
 
 	for (;; waitcnt++) {
 		/*
diff --git a/kernel/locking/qspinlock_stat.h b/kernel/locking/qspinlock_stat.h
index 4a30ef63c607..6bd78c0740fc 100644
--- a/kernel/locking/qspinlock_stat.h
+++ b/kernel/locking/qspinlock_stat.h
@@ -22,13 +22,14 @@
  *   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 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
+ *   lock_pending	- # of locking operations via pending code
+ *   lock_slowpath	- # of locking operations via MCS lock queue
  *
  * Writing to the "reset_counters" file will reset all the above counter
  * values.
@@ -46,13 +47,14 @@ 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,
 	qstat_pv_wait_early,
 	qstat_pv_wait_head,
 	qstat_pv_wait_node,
+	qstat_lock_pending,
+	qstat_lock_slowpath,
 	qstat_num,	/* Total number of statistical counters */
 	qstat_reset_cnts = qstat_num,
 };
@@ -73,12 +75,13 @@ 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",
 	[qstat_pv_wait_head]       = "pv_wait_head",
 	[qstat_pv_wait_node]       = "pv_wait_node",
+	[qstat_lock_pending]       = "lock_pending",
+	[qstat_lock_slowpath]      = "lock_slowpath",
 	[qstat_reset_cnts]         = "reset_counters",
 };
 
-- 
2.1.4

  parent reply	other threads:[~2018-04-26 10:34 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-26 10:34 [PATCH v3 00/14] kernel/locking: qspinlock improvements Will Deacon
2018-04-26 10:34 ` [PATCH v3 01/14] barriers: Introduce smp_cond_load_relaxed and atomic_cond_read_relaxed Will Deacon
2018-04-27  9:36   ` [tip:locking/core] locking/barriers: Introduce smp_cond_load_relaxed() and atomic_cond_read_relaxed() tip-bot for Will Deacon
2018-04-26 10:34 ` [PATCH v3 02/14] locking/qspinlock: Merge struct __qspinlock into struct qspinlock Will Deacon
2018-04-27  9:37   ` [tip:locking/core] locking/qspinlock: Merge 'struct __qspinlock' into 'struct qspinlock' tip-bot for Will Deacon
2018-04-26 10:34 ` [PATCH v3 03/14] locking/qspinlock: Bound spinning on pending->locked transition in slowpath Will Deacon
2018-04-27  9:37   ` [tip:locking/core] " tip-bot for Will Deacon
2018-04-26 10:34 ` [PATCH v3 04/14] locking/qspinlock/x86: Increase _Q_PENDING_LOOPS upper bound Will Deacon
2018-04-27  9:38   ` [tip:locking/core] " tip-bot for Will Deacon
2018-04-26 10:34 ` [PATCH v3 05/14] locking/qspinlock: Remove unbounded cmpxchg loop from locking slowpath Will Deacon
2018-04-26 15:53   ` Peter Zijlstra
2018-04-26 16:55     ` Will Deacon
2018-04-28 12:45       ` Peter Zijlstra
2018-04-30  8:53         ` Will Deacon
2018-04-26 20:16   ` Waiman Long
2018-04-27 10:16     ` Will Deacon
2018-04-27 11:01       ` [tip:locking/core] locking/qspinlock: Remove duplicate clear_pending() function from PV code tip-bot for Will Deacon
2018-04-27 13:09       ` [PATCH v3 05/14] locking/qspinlock: Remove unbounded cmpxchg loop from locking slowpath Waiman Long
2018-04-27  9:39   ` [tip:locking/core] locking/qspinlock: Remove unbounded cmpxchg() " tip-bot for Will Deacon
2018-04-26 10:34 ` [PATCH v3 06/14] locking/qspinlock: Kill cmpxchg loop when claiming lock from head of queue Will Deacon
2018-04-27  9:39   ` [tip:locking/core] locking/qspinlock: Kill cmpxchg() " tip-bot for Will Deacon
2018-04-26 10:34 ` [PATCH v3 07/14] locking/qspinlock: Use atomic_cond_read_acquire Will Deacon
2018-04-27  9:40   ` [tip:locking/core] locking/qspinlock: Use atomic_cond_read_acquire() tip-bot for Will Deacon
2018-04-26 10:34 ` [PATCH v3 08/14] locking/mcs: Use smp_cond_load_acquire() in mcs spin loop Will Deacon
2018-04-27  9:40   ` [tip:locking/core] locking/mcs: Use smp_cond_load_acquire() in MCS " tip-bot for Jason Low
2018-04-26 10:34 ` [PATCH v3 09/14] locking/qspinlock: Use smp_cond_load_relaxed to wait for next node Will Deacon
2018-04-27  9:41   ` [tip:locking/core] locking/qspinlock: Use smp_cond_load_relaxed() " tip-bot for Will Deacon
2018-04-26 10:34 ` [PATCH v3 10/14] locking/qspinlock: Make queued_spin_unlock use smp_store_release Will Deacon
2018-04-27  9:42   ` [tip:locking/core] locking/qspinlock: Use smp_store_release() in queued_spin_unlock() tip-bot for Will Deacon
2018-04-26 10:34 ` [PATCH v3 11/14] locking/qspinlock: Elide back-to-back RELEASE operations with smp_wmb() Will Deacon
2018-04-27  9:42   ` [tip:locking/core] " tip-bot for Will Deacon
2018-04-26 10:34 ` [PATCH v3 12/14] locking/qspinlock: Use try_cmpxchg instead of cmpxchg when locking Will Deacon
2018-04-27  9:43   ` [tip:locking/core] locking/qspinlock: Use try_cmpxchg() instead of cmpxchg() " tip-bot for Will Deacon
2018-04-26 10:34 ` Will Deacon [this message]
2018-04-27  9:43   ` [tip:locking/core] locking/qspinlock: Add stat tracking for pending vs. slowpath tip-bot for Waiman Long
2018-04-26 10:34 ` [PATCH v3 14/14] MAINTAINERS: Add myself as a co-maintainer for LOCKING PRIMITIVES Will Deacon
2018-04-26 15:55   ` Peter Zijlstra
2018-04-27  9:44   ` [tip:locking/core] MAINTAINERS: Add myself as a co-maintainer for the locking subsystem tip-bot for Will Deacon
2018-04-26 15:54 ` [PATCH v3 00/14] kernel/locking: qspinlock improvements Peter Zijlstra
2018-04-27  9:33   ` Ingo Molnar
2018-04-26 20:18 ` Waiman Long

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