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author | Shaohua Li <shli@fb.com> | 2017-10-06 17:55:59 -0700 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2017-10-10 13:48:14 -0600 |
commit | eca8b53a6769e60d6d8240d71202d73b0af81901 (patch) | |
tree | 6a042bf2b35595851ca83b9e77eec8ca05f1e38a | |
parent | 53cfdc10a95d03fbc82970d682a32696d19ef886 (diff) | |
download | linux-eca8b53a6769e60d6d8240d71202d73b0af81901.tar.gz linux-eca8b53a6769e60d6d8240d71202d73b0af81901.tar.bz2 linux-eca8b53a6769e60d6d8240d71202d73b0af81901.zip |
blk-stat: delete useless code
Fix two issues:
- the per-cpu stat flush is unnecessary, nobody uses per-cpu stat except
sum it to global stat. We can do the calculation there. The flush just
wastes cpu time.
- some fields are signed int/s64. I don't see the point.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r-- | block/blk-stat.c | 45 | ||||
-rw-r--r-- | include/linux/blk_types.h | 5 |
2 files changed, 9 insertions, 41 deletions
diff --git a/block/blk-stat.c b/block/blk-stat.c index c52356d90fe3..3a2f3c96f367 100644 --- a/block/blk-stat.c +++ b/block/blk-stat.c @@ -11,8 +11,6 @@ #include "blk-mq.h" #include "blk.h" -#define BLK_RQ_STAT_BATCH 64 - struct blk_queue_stats { struct list_head callbacks; spinlock_t lock; @@ -23,45 +21,21 @@ static void blk_stat_init(struct blk_rq_stat *stat) { stat->min = -1ULL; stat->max = stat->nr_samples = stat->mean = 0; - stat->batch = stat->nr_batch = 0; -} - -static void blk_stat_flush_batch(struct blk_rq_stat *stat) -{ - const s32 nr_batch = READ_ONCE(stat->nr_batch); - const s32 nr_samples = READ_ONCE(stat->nr_samples); - - if (!nr_batch) - return; - if (!nr_samples) - stat->mean = div64_s64(stat->batch, nr_batch); - else { - stat->mean = div64_s64((stat->mean * nr_samples) + - stat->batch, - nr_batch + nr_samples); - } - - stat->nr_samples += nr_batch; - stat->nr_batch = stat->batch = 0; + stat->batch = 0; } +/* src is a per-cpu stat, mean isn't initialized */ static void blk_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src) { - blk_stat_flush_batch(src); - if (!src->nr_samples) return; dst->min = min(dst->min, src->min); dst->max = max(dst->max, src->max); - if (!dst->nr_samples) - dst->mean = src->mean; - else { - dst->mean = div64_s64((src->mean * src->nr_samples) + - (dst->mean * dst->nr_samples), - dst->nr_samples + src->nr_samples); - } + dst->mean = div_u64(src->batch + dst->mean * dst->nr_samples, + dst->nr_samples + src->nr_samples); + dst->nr_samples += src->nr_samples; } @@ -69,13 +43,8 @@ static void __blk_stat_add(struct blk_rq_stat *stat, u64 value) { stat->min = min(stat->min, value); stat->max = max(stat->max, value); - - if (stat->batch + value < stat->batch || - stat->nr_batch + 1 == BLK_RQ_STAT_BATCH) - blk_stat_flush_batch(stat); - stat->batch += value; - stat->nr_batch++; + stat->nr_samples++; } void blk_stat_add(struct request *rq) @@ -84,7 +53,7 @@ void blk_stat_add(struct request *rq) struct blk_stat_callback *cb; struct blk_rq_stat *stat; int bucket; - s64 now, value; + u64 now, value; now = __blk_stat_time(ktime_to_ns(ktime_get())); if (now < blk_stat_time(&rq->issue_stat)) diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h index a2d2aa709cef..3385c89f402e 100644 --- a/include/linux/blk_types.h +++ b/include/linux/blk_types.h @@ -329,11 +329,10 @@ static inline bool blk_qc_t_is_internal(blk_qc_t cookie) } struct blk_rq_stat { - s64 mean; + u64 mean; u64 min; u64 max; - s32 nr_samples; - s32 nr_batch; + u32 nr_samples; u64 batch; }; |