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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>
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@ -11,8 +11,6 @@
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#include "blk-mq.h"
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#include "blk.h"
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#define BLK_RQ_STAT_BATCH 64
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struct blk_queue_stats {
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struct list_head callbacks;
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spinlock_t lock;
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@ -23,45 +21,21 @@ static void blk_stat_init(struct blk_rq_stat *stat)
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{
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stat->min = -1ULL;
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stat->max = stat->nr_samples = stat->mean = 0;
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stat->batch = stat->nr_batch = 0;
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}
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static void blk_stat_flush_batch(struct blk_rq_stat *stat)
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{
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const s32 nr_batch = READ_ONCE(stat->nr_batch);
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const s32 nr_samples = READ_ONCE(stat->nr_samples);
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if (!nr_batch)
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return;
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if (!nr_samples)
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stat->mean = div64_s64(stat->batch, nr_batch);
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else {
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stat->mean = div64_s64((stat->mean * nr_samples) +
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stat->batch,
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nr_batch + nr_samples);
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}
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stat->nr_samples += nr_batch;
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stat->nr_batch = stat->batch = 0;
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stat->batch = 0;
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}
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/* src is a per-cpu stat, mean isn't initialized */
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static void blk_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src)
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{
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blk_stat_flush_batch(src);
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if (!src->nr_samples)
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return;
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dst->min = min(dst->min, src->min);
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dst->max = max(dst->max, src->max);
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if (!dst->nr_samples)
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dst->mean = src->mean;
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else {
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dst->mean = div64_s64((src->mean * src->nr_samples) +
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(dst->mean * dst->nr_samples),
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dst->nr_samples + src->nr_samples);
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}
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dst->mean = div_u64(src->batch + dst->mean * dst->nr_samples,
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dst->nr_samples + src->nr_samples);
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dst->nr_samples += src->nr_samples;
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}
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@ -69,13 +43,8 @@ static void __blk_stat_add(struct blk_rq_stat *stat, u64 value)
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{
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stat->min = min(stat->min, value);
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stat->max = max(stat->max, value);
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if (stat->batch + value < stat->batch ||
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stat->nr_batch + 1 == BLK_RQ_STAT_BATCH)
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blk_stat_flush_batch(stat);
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stat->batch += value;
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stat->nr_batch++;
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stat->nr_samples++;
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}
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void blk_stat_add(struct request *rq)
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@ -84,7 +53,7 @@ void blk_stat_add(struct request *rq)
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struct blk_stat_callback *cb;
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struct blk_rq_stat *stat;
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int bucket;
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s64 now, value;
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u64 now, value;
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now = __blk_stat_time(ktime_to_ns(ktime_get()));
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if (now < blk_stat_time(&rq->issue_stat))
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@ -329,11 +329,10 @@ static inline bool blk_qc_t_is_internal(blk_qc_t cookie)
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}
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struct blk_rq_stat {
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s64 mean;
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u64 mean;
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u64 min;
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u64 max;
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s32 nr_samples;
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s32 nr_batch;
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u32 nr_samples;
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u64 batch;
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};
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