On Tue, 29 May 2007 14:52:51 +0200 Peter Zijlstra <[email protected]> wrote:
> Introduce the core lock statistics code.
>
I must say that an aggregate addition of 27 ifdefs is a bit sad. And there
is some easy stuff here.
> +#ifdef CONFIG_PROVE_LOCKING
> +int prove_locking = 1;
> +module_param(prove_locking, int, 0644);
> +#endif
#else
#define prove_locking 0
#endif
> +
> +#ifdef CONFIG_LOCK_STAT
> +int lock_stat = 1;
> +module_param(lock_stat, int, 0644);
> +#endif
ditto.
>
> ...
>
> +struct lock_class_stats lock_stats(struct lock_class *class)
> +{
> + struct lock_class_stats stats;
> + int cpu, i;
> +
> + memset(&stats, 0, sizeof(struct lock_class_stats));
> + for_each_possible_cpu(cpu) {
> + struct lock_class_stats *pcs =
> + &per_cpu(lock_stats, cpu)[class - lock_classes];
> +
> + for (i = 0; i < ARRAY_SIZE(stats.contention_point); i++)
> + stats.contention_point[i] += pcs->contention_point[i];
> +
> + lock_time_add(&pcs->read_waittime, &stats.read_waittime);
> + lock_time_add(&pcs->write_waittime, &stats.write_waittime);
> +
> + lock_time_add(&pcs->read_holdtime, &stats.read_holdtime);
> + lock_time_add(&pcs->write_holdtime, &stats.write_holdtime);
> + }
> +
> + return stats;
> +}
hm, that isn't trying to be very efficient.
> @@ -2035,6 +2131,11 @@ static int __lock_acquire(struct lockdep
> int chain_head = 0;
> u64 chain_key;
>
> +#ifdef CONFIG_PROVE_LOCKING
> + if (!prove_locking)
> + check = 1;
> +#endif
Removable
> +#ifdef CONFIG_LOCK_STAT
> +static void lock_release_holdtime(struct held_lock *hlock)
> +{
> + struct lock_class_stats *stats;
> + unsigned long long holdtime;
> +
> + if (!lock_stat)
> + return;
> +
> + holdtime = sched_clock() - hlock->holdtime_stamp;
> +
> + stats = get_lock_stats(hlock->class);
> +
> + if (hlock->read)
> + lock_time_inc(&stats->read_holdtime, holdtime);
> + else
> + lock_time_inc(&stats->write_holdtime, holdtime);
> +
> + put_lock_stats(stats);
> +}
> +#else
> +static void lock_release_holdtime(struct held_lock *hlock)
inline
> +{
> +}
> +#endif
> +
> ...
>
> @@ -2456,6 +2712,14 @@ void lock_acquire(struct lockdep_map *lo
> {
> unsigned long flags;
>
> +#ifdef CONFIG_LOCK_STAT
> + if (unlikely(!lock_stat))
> +#endif
removable
> +#ifdef CONFIG_PROVE_LOCKING
> + if (unlikely(!prove_locking))
> +#endif
removable
> @@ -2475,6 +2739,14 @@ void lock_release(struct lockdep_map *lo
> {
> unsigned long flags;
>
> +#ifdef CONFIG_LOCK_STAT
> + if (unlikely(!lock_stat))
> +#endif
removable
> +#ifdef CONFIG_PROVE_LOCKING
> + if (unlikely(!prove_locking))
> +#endif
> + return;
> +
> if (unlikely(current->lockdep_recursion))
> return;
>
>
> ...
>
> +#ifdef CONFIG_LOCK_STAT
> +
> +extern void lock_contended(struct lockdep_map *lock, unsigned long ip);
> +extern void lock_acquired(struct lockdep_map *lock);
> +
> +#define LOCK_CONTENDED(_lock, try, lock) \
> +do { \
> + if (!try(_lock)) { \
> + lock_contended(&(_lock)->dep_map, _RET_IP_); \
> + lock(_lock); \
> + lock_acquired(&(_lock)->dep_map); \
> + } \
> +} while (0)
> +
> +#else /* CONFIG_LOCK_STAT */
> +
> +#define lock_contended(l, i) do { } while (0)
> +#define lock_acquired(l) do { } while (0)
inlines are better.
> +#define LOCK_CONTENDED(_lock, try, lock) \
> + lock(_lock)
> +
> +#endif /* CONFIG_LOCK_STAT */
> +
> },
>
> ...
>
> +#ifdef CONFIG_PROVE_LOCKING
> + {
> + .ctl_name = KERN_PROVE_LOCKING,
> + .procname = "prove_locking",
> + .data = &prove_locking,
> + .maxlen = sizeof(int),
> + .mode = 0644,
> + .proc_handler = &proc_dointvec,
> + },
> +#endif
> +#ifdef CONFIG_LOCK_STAT
> + {
> + .ctl_name = KERN_LOCK_STAT,
> + .procname = "lock_stat",
> + .data = &lock_stat,
> + .maxlen = sizeof(int),
> + .mode = 0644,
> + .proc_handler = &proc_dointvec,
> + },
> +#endif
Please use CTL_UNNUNBERED for new sysctls.
> { .ctl_name = 0 }
> };
> Index: linux-2.6-git/include/linux/sysctl.h
> ===================================================================
> --- linux-2.6-git.orig/include/linux/sysctl.h
> +++ linux-2.6-git/include/linux/sysctl.h
> @@ -166,6 +166,8 @@ enum
> KERN_NMI_WATCHDOG=75, /* int: enable/disable nmi watchdog */
> KERN_PANIC_ON_NMI=76, /* int: whether we will panic on an unrecovered */
> KERN_POWEROFF_CMD=77, /* string: poweroff command line */
> + KERN_PROVE_LOCKING=78, /* int: enable lock dependancy checking */
> + KERN_LOCK_STAT=79, /* int: enable lock statistics */
> };
And lose these.
So I'm inclined to ask if you can redo these pathces with a view to reducing
the ifdef density with a bit of restructuring.
We could do that as a followon patch I guess. Nicer not to though.
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