在 15/6/10 上午5:22, Mikulas Patocka 写道:
> This patch adds an option to dm statistics to collect and report the
> histogram of latencies.
>
> Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
>
> ---
> Documentation/device-mapper/statistics.txt | 21 ++-
> drivers/md/dm-stats.c | 201 +++++++++++++++++++++++++----
> 2 files changed, 196 insertions(+), 26 deletions(-)
>
> Index: linux-4.1-rc7/drivers/md/dm-stats.c
> ===================================================================
> --- linux-4.1-rc7.orig/drivers/md/dm-stats.c 2015-06-08 16:38:43.000000000 +0200
> +++ linux-4.1-rc7/drivers/md/dm-stats.c 2015-06-08 17:02:01.000000000 +0200
> @@ -29,6 +29,7 @@ struct dm_stat_percpu {
> unsigned long long io_ticks[2];
> unsigned long long io_ticks_total;
> unsigned long long time_in_queue;
> + unsigned long long *histogram;
> };
>
> struct dm_stat_shared {
[snip]
> @@ -619,6 +700,11 @@ static void __dm_stat_init_temporary_per
> shared->tmp.io_ticks[WRITE] += ACCESS_ONCE(p->io_ticks[WRITE]);
> shared->tmp.io_ticks_total += ACCESS_ONCE(p->io_ticks_total);
> shared->tmp.time_in_queue += ACCESS_ONCE(p->time_in_queue);
> + if (s->n_histogram_entries) {
> + unsigned i;
> + for (i = 0; i < s->n_histogram_entries + 1; i++)
> + shared->tmp.histogram[i] += ACCESS_ONCE(p->histogram[i]);
s->n_histogram_entries + 1 in for() looping will be calculated many times, maybe this way could be better,
+ if (s->n_histogram_entries) {
+ unsigned i, j;
+ j = s->n_histogram_entries + 1;
+ for (i = 0; i < j; i++)
+ shared->tmp.histogram[i] += ACCESS_ONCE(p->histogram[i]);
> + }
> }
> }
>
> @@ -648,6 +734,15 @@ static void __dm_stat_clear(struct dm_st
> p->io_ticks_total -= shared->tmp.io_ticks_total;
> p->time_in_queue -= shared->tmp.time_in_queue;
> local_irq_enable();
> + if (s->n_histogram_entries) {
> + unsigned i;
> + for (i = 0; i < s->n_histogram_entries + 1; i++) {
Same situation here,
+ unsigned i, j;
+ j = s->n_histogram_entries + 1;
+ for (i = 0; i < j; i++) {
> + local_irq_disable();
> + p = &s->stat_percpu[smp_processor_id()][x];
> + p->histogram[i] -= shared->tmp.histogram[i];
> + local_irq_enable();
> + }
> + }
> }
> }
>
> @@ -737,7 +832,7 @@ static int dm_stats_print(struct dm_stat
>
> __dm_stat_init_temporary_percpu_totals(shared, s, x);
>
> - DMEMIT("%llu+%llu %llu %llu %llu %llu %llu %llu %llu %llu %d %llu %llu %llu %llu\n",
> + DMEMIT("%llu+%llu %llu %llu %llu %llu %llu %llu %llu %llu %d %llu %llu %llu %llu",
> (unsigned long long)start,
> (unsigned long long)step,
> shared->tmp.ios[READ],
> @@ -753,6 +848,13 @@ static int dm_stats_print(struct dm_stat
> dm_jiffies_to_msec64(s, shared->tmp.time_in_queue),
> dm_jiffies_to_msec64(s, shared->tmp.io_ticks[READ]),
> dm_jiffies_to_msec64(s, shared->tmp.io_ticks[WRITE]));
> + if (s->n_histogram_entries) {
> + unsigned i;
> + for (i = 0; i < s->n_histogram_entries + 1; i++) {
Same situation here,
+ unsigned i, j;
+ j = s->n_histogram_entries + 1;
+ for (i = 0; i < j; i++) {
> + DMEMIT("%s%llu", !i ? " " : ":", shared->tmp.histogram[i]);
> + }
> + }
> + DMEMIT("\n");
>
> if (unlikely(sz + 1 >= maxlen))
> goto buffer_overflow;
[snip]
Coly
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