[PATCH 3/8] bfq: Store full bitmap depth in bfq_data

Jan Kara
2021-10-06T17:32:04Z

Store bitmap depth shift inside bfq_data so that we can use it in
bfq_limit_depth() for proportioning when limiting number of available
request tags for a cgroup.

Signed-off-by: Jan Kara <jack@suse.cz>
---
block/bfq-iosched.c | 10 ++++++----
block/bfq-iosched.h | 1 +
2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 4d9e04edb614..c93a74b8e9c8 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -6855,7 +6855,9 @@ static unsigned int bfq_update_depths(struct bfq_data *bfqd,
struct sbitmap_queue *bt)
{
unsigned int i, j, min_shallow = UINT_MAX;
+ unsigned int depth = 1U << bt->sb.shift;

+ bfqd->full_depth_shift = bt->sb.shift;
/*
* In-word depths if no bfq_queue is being weight-raised:
* leaving 25% of tags only for sync reads.
@@ -6867,13 +6869,13 @@ 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(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((depth * 3) >> 2, 1U);

/*
* In-word depths in case some bfq_queue is being weight-
@@ -6883,9 +6885,9 @@ 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((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((depth * 6) >> 4, 1U);

for (i = 0; i < 2; i++)
for (j = 0; j < 2; j++)
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 3787cfb0febb..820cb8c2d1fe 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -769,6 +769,7 @@ struct bfq_data {
* function)
*/
unsigned int word_depths[2][2];
+ unsigned int full_depth_shift;
};

enum bfqq_state_flags {
--
2.26.2