[PATCH v3 14/14] bfq: optimize the calculation of bfq_weight_to_ioprio()

brookxu
2021-03-25T06:59:21Z

The value range of ioprio is [0, 7], but the result of
bfq_weight_to_ioprio() may exceed this range, so simple
optimization is required.

Signed-off-by: Chunguang Xu <brookxu@tencent.com>
---
block/bfq-wf2q.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index b477a9b..1b91c8b 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -586,8 +586,9 @@ unsigned short bfq_ioprio_to_weight(int ioprio)
*/
static unsigned short bfq_weight_to_ioprio(int weight)
{
- return max_t(int, 0,
- IOPRIO_BE_NR * BFQ_WEIGHT_CONVERSION_COEFF - weight);
+ int ioprio = IOPRIO_BE_NR - weight / BFQ_WEIGHT_CONVERSION_COEFF;
+
+ return ioprio < 0 ? 0 : min_t(int, ioprio, IOPRIO_BE_NR - 1);
}

static void bfq_get_entity(struct bfq_entity *entity)
--
1.8.3.1