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Date: Fri, 26 Dec 2008 21:13:22 +0800
From: "Yang Xi" <yangxilkm@...il.com>
To: "Ingo Molnar" <mingo@...e.hu>
Cc: "Peter Zijlstra" <a.p.zijlstra@...llo.nl>,
linux-kernel@...r.kernel.org, chyyuu <chyyuu@...il.com>
Subject: Re: [PATCH 2.6.28-rc4]lock_stat: Add "con-hungry" to show that how many person-time fight for the ticket spinlock
> #ifndef spin_nr_contended
> # define spin_nr_contended(lock) (spin_is_contended(lock) ? 1 : 0)
> #endif
And I change the spin_nr_contended to spin_nr_contender
> do we need the ->isticketspinlock distinction? Cannot we call
> spin_nr_contended() for all spinlocks? (it's just that for ticket
> spinlocks we get a real value out of it - for normal spinlocks we only get
> 0/1 out of it. But that is not a problem really.)
Not only the spin lock invokes lock_contended(). So we have to know
the invoker is spin lock. I have changed the isticketspinlock to
isspinlock to avoid the confusion.
>
> also, please rename 'hungry' to something more descriptive: for example
> 'nr_contended' fits pretty well?
I changed hungry to contender. con-hungry to nr-contender, max hungry
to max-contender.
Here is the patch
Signed-off-by: Yangxi <hiyangxi@...il.com>
---
arch/x86/include/asm/spinlock.h | 9 +++++++++
include/linux/lockdep.h | 5 ++++-
include/linux/spinlock.h | 4 ++++
kernel/lockdep.c | 21 ++++++++++++++++++++-
kernel/lockdep_proc.c | 10 +++++++---
lib/spinlock_debug.c | 1 +
6 files changed, 45 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index d17c919..5c52960 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -172,6 +172,15 @@ static inline int
__ticket_spin_is_contended(raw_spinlock_t *lock)
return (((tmp >> TICKET_SHIFT) - tmp) & ((1 << TICKET_SHIFT) - 1)) > 1;
}
+static inline int __ticket_spin_nr_contender(raw_spinlock_t *lock)
+{
+ int tmp = ACCESS_ONCE(lock->slock);
+
+ return (((tmp >> TICKET_SHIFT) - tmp) & ((1 << TICKET_SHIFT) - 1)) + 1;
+}
+
+#define spin_nr_contender(lock) __ticket_spin_nr_contender(&(lock)->raw_lock)
+
#ifdef CONFIG_PARAVIRT
/*
* Define virtualization-friendly old-style lock byte lock, for use in
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 331e5f1..d777102 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -136,6 +136,8 @@ enum bounce_type {
bounce_acquired_read,
bounce_contended_write,
bounce_contended_read,
+ nr_contender,
+ max_contender,
nr_bounce_types,
bounce_acquired = bounce_acquired_write,
@@ -164,7 +166,8 @@ struct lockdep_map {
struct lock_class *class_cache;
const char *name;
#ifdef CONFIG_LOCK_STAT
- int cpu;
+ unsigned int cpu:32;
+ unsigned int isspinlock:1;
#endif
};
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h
index e0c0fcc..54b8a88 100644
--- a/include/linux/spinlock.h
+++ b/include/linux/spinlock.h
@@ -127,6 +127,10 @@ do { \
#define spin_is_contended(lock) __raw_spin_is_contended(&(lock)->raw_lock)
#endif
+#ifndef spin_nr_contender
+#define spin_nr_contender(lock) (spin_is_contended(lock) ? 1 : 0)
+#endif
+
/**
* spin_unlock_wait - wait until the spinlock gets unlocked
* @lock: the spinlock in question.
diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 06e1571..9a9e7d7 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -191,8 +191,14 @@ struct lock_class_stats lock_stats(struct
lock_class *class)
lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
- for (i = 0; i < ARRAY_SIZE(stats.bounces); i++)
+ for (i = 0; i < ARRAY_SIZE(stats.bounces); i++) {
+ if (i == max_contender) {
+ if (stats.bounces[i] < pcs->bounces[i])
+ stats.bounces[i] = pcs->bounces[i];
+ continue;
+ }
stats.bounces[i] += pcs->bounces[i];
+ }
}
return stats;
@@ -2998,9 +3004,16 @@ __lock_contended(struct lockdep_map *lock,
unsigned long ip)
struct task_struct *curr = current;
struct held_lock *hlock, *prev_hlock;
struct lock_class_stats *stats;
+ unsigned long contender;
+ spinlock_t *lock_ptr;
unsigned int depth;
int i, point;
+ if (lock->isspinlock) {
+ lock_ptr = container_of(lock, spinlock_t, dep_map);
+ contender = spin_nr_contender(lock_ptr);
+ }
+
depth = curr->lockdep_depth;
if (DEBUG_LOCKS_WARN_ON(!depth))
return;
@@ -3030,6 +3043,12 @@ found_it:
stats->contention_point[point]++;
if (lock->cpu != smp_processor_id())
stats->bounces[bounce_contended + !!hlock->read]++;
+ stats->bounces[nr_contender] += contender;
+ if (lock->isspinlock) {
+ if (stats->bounces[max_contender] < contender)
+ stats->bounces[max_contender] = contender;
+ }
+
put_lock_stats(stats);
}
diff --git a/kernel/lockdep_proc.c b/kernel/lockdep_proc.c
index 20dbcbf..c87b42c 100644
--- a/kernel/lockdep_proc.c
+++ b/kernel/lockdep_proc.c
@@ -535,6 +535,8 @@ static void seq_stats(struct seq_file *m, struct
lock_stat_data *data)
seq_printf(m, "%40s:", name);
seq_printf(m, "%14lu ", stats->bounces[bounce_contended_write]);
+ seq_printf(m, "%14lu ", stats->bounces[nr_contender]);
+ seq_printf(m, "%14lu ", stats->bounces[max_contender]);
seq_lock_time(m, &stats->write_waittime);
seq_printf(m, " %14lu ", stats->bounces[bounce_acquired_write]);
seq_lock_time(m, &stats->write_holdtime);
@@ -583,11 +585,13 @@ static void seq_stats(struct seq_file *m, struct
lock_stat_data *data)
static void seq_header(struct seq_file *m)
{
seq_printf(m, "lock_stat version 0.2\n");
- seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
- seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s "
+ seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
+ seq_printf(m, "%40s %14s %14s %14s %14s %14s %14s %14s %14s %14s %14s "
"%14s %14s\n",
"class name",
"con-bounces",
+ "nr-contender",
+ "max-contender",
"contentions",
"waittime-min",
"waittime-max",
@@ -597,7 +601,7 @@ static void seq_header(struct seq_file *m)
"holdtime-min",
"holdtime-max",
"holdtime-total");
- seq_line(m, '-', 0, 40 + 1 + 10 * (14 + 1));
+ seq_line(m, '-', 0, 40 + 1 + 12 * (14 + 1));
seq_printf(m, "\n");
}
diff --git a/lib/spinlock_debug.c b/lib/spinlock_debug.c
index 9c4b025..5c6e06f 100644
--- a/lib/spinlock_debug.c
+++ b/lib/spinlock_debug.c
@@ -27,6 +27,7 @@ void __spin_lock_init(spinlock_t *lock, const char *name,
lock->magic = SPINLOCK_MAGIC;
lock->owner = SPINLOCK_OWNER_INIT;
lock->owner_cpu = -1;
+ lock->dep_map.isspinlock = 1;
}
EXPORT_SYMBOL(__spin_lock_init);
--
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