bfq-iosched: remove unused variable

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>

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 0cd8aa80c32de751f96694796e64fdf9362af1ea..10294124d597c9d2c914b20021e907f9073eac17 100644 (file)
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -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)

diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 8ec7ff92cd6f7a950b1c871a60d84ff5837c3135..faac509cb35ed99f218c9f060a92b13f507f8b24 100644 (file)
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -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)