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authorJan Kara <jack@suse.cz>2020-12-10 10:44:33 +0100
committerJens Axboe <axboe@kernel.dk>2021-01-05 11:33:50 -0700
commit6d4d273588378c65915acaf7b2ee74e9dd9c130a (patch)
tree6186d79037d2a486cc6f9e386edc531a10e7fb3b
parentd16baa3f1453c14d680c5fee01cd122a22d0e0ce (diff)
bfq: Fix computation of shallow depth
BFQ computes number of tags it allows to be allocated for each request type based on tag bitmap. However it uses 1 << bitmap.shift as number of available tags which is wrong. 'shift' is just an internal bitmap value containing logarithm of how many bits bitmap uses in each bitmap word. Thus number of tags allowed for some request types can be far to low. Use proper bitmap.depth which has the number of tags instead. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--block/bfq-iosched.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 9e81d1052091..9e4eb0fc1c16 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -6332,13 +6332,13 @@ static unsigned int bfq_update_depths(struct bfq_data *bfqd,
* limit 'something'.
*/
/* no more than 50% of tags for async I/O */
- bfqd->word_depths[0][0] = max((1U << bt->sb.shift) >> 1, 1U);
+ bfqd->word_depths[0][0] = max(bt->sb.depth >> 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 << bt->sb.shift) * 3) >> 2, 1U);
+ bfqd->word_depths[0][1] = max((bt->sb.depth * 3) >> 2, 1U);
/*
* In-word depths in case some bfq_queue is being weight-
@@ -6348,9 +6348,9 @@ static unsigned int bfq_update_depths(struct bfq_data *bfqd,
* shortage.
*/
/* no more than ~18% of tags for async I/O */
- bfqd->word_depths[1][0] = max(((1U << bt->sb.shift) * 3) >> 4, 1U);
+ bfqd->word_depths[1][0] = max((bt->sb.depth * 3) >> 4, 1U);
/* no more than ~37% of tags for sync writes (~20% extra tags) */
- bfqd->word_depths[1][1] = max(((1U << bt->sb.shift) * 6) >> 4, 1U);
+ bfqd->word_depths[1][1] = max((bt->sb.depth * 6) >> 4, 1U);
for (i = 0; i < 2; i++)
for (j = 0; j < 2; j++)