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bfq-iosched: remove unused variable

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bfqd->sb_shift was attempted used as a cache for the sbitmap queue
shift, but we don't need it, as it never changes. Kill it with fire.

Acked-by: Paolo Valente <paolo.valente@linaro.org>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2018-05-09 15:25:22 -06:00
parent f0635b8a41
commit bd7d4ef6a4
2 changed files with 7 additions and 15 deletions
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16
block/bfq-iosched.c
View File

@ -5085,26 +5085,24 @@ void bfq_put_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg)
*/
static void bfq_update_depths(struct bfq_data *bfqd, struct sbitmap_queue *bt)
{
bfqd->sb_shift = bt->sb.shift;
/*
* In-word depths if no bfq_queue is being weight-raised:
* leaving 25% of tags only for sync reads.
*
* In next formulas, right-shift the value
* (1U<<bfqd->sb_shift), instead of computing directly
* (1U<<(bfqd->sb_shift - something)), to be robust against
* any possible value of bfqd->sb_shift, without having to
* (1U<<bt->sb.shift), instead of computing directly
* (1U<<(bt->sb.shift - something)), to be robust against
* any possible value of bt->sb.shift, without having to
* limit 'something'.
*/
/* no more than 50% of tags for async I/O */
bfqd->word_depths[0][0] = max((1U<<bfqd->sb_shift)>>1, 1U);
bfqd->word_depths[0][0] = max((1U << bt->sb.shift) >> 1, 1U);
/*
* no more than 75% of tags for sync writes (25% extra tags
* w.r.t. async I/O, to prevent async I/O from starving sync
* writes)
*/
bfqd->word_depths[0][1] = max(((1U<<bfqd->sb_shift) * 3)>>2, 1U);
bfqd->word_depths[0][1] = max(((1U << bt->sb.shift) * 3) >> 2, 1U);
/*
* In-word depths in case some bfq_queue is being weight-
@ -5114,9 +5112,9 @@ static void bfq_update_depths(struct bfq_data *bfqd, struct sbitmap_queue *bt)
* shortage.
*/
/* no more than ~18% of tags for async I/O */
bfqd->word_depths[1][0] = max(((1U<<bfqd->sb_shift) * 3)>>4, 1U);
bfqd->word_depths[1][0] = max(((1U << bt->sb.shift) * 3) >> 4, 1U);
/* no more than ~37% of tags for sync writes (~20% extra tags) */
bfqd->word_depths[1][1] = max(((1U<<bfqd->sb_shift) * 6)>>4, 1U);
bfqd->word_depths[1][1] = max(((1U << bt->sb.shift) * 6) >> 4, 1U);
}
static int bfq_init_hctx(struct blk_mq_hw_ctx *hctx, unsigned int index)

6
block/bfq-iosched.h
View File

@ -635,12 +635,6 @@ struct bfq_data {
/* bfqq associated with the task issuing current bio for merging */
struct bfq_queue *bio_bfqq;
/*
* Cached sbitmap shift, used to compute depth limits in
* bfq_update_depths.
*/
unsigned int sb_shift;
/*
* Depth limits used in bfq_limit_depth (see comments on the
* function)