From: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx> According to current policy, RT tasks possess the privilege for both of CPU and IO scheduler which could have the preempted CFS tasks suffer big IO-latency unfairly. This commit introduce an approximate method to deduct the preempt affection. TaskA sched in | | | submit_bio | | | fifo_time = jiffies + expire (insert_request) TaskB sched in | | preempted by RT task |\ | This period time is unfair to TaskB's IO request, should be adjust |/ submit_bio | | | fifo_time = jiffies + expire * CFS_PROPORTION(rq) (insert_request) Signed-off-by: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx> --- block/mq-deadline.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/block/mq-deadline.c b/block/mq-deadline.c index f958e79277b8..43c08c3d6f18 100644 --- a/block/mq-deadline.c +++ b/block/mq-deadline.c @@ -15,6 +15,7 @@ #include <linux/compiler.h> #include <linux/rbtree.h> #include <linux/sbitmap.h> +#include "../kernel/sched/sched.h" #include <trace/events/block.h> @@ -802,6 +803,7 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, u8 ioprio_class = IOPRIO_PRIO_CLASS(ioprio); struct dd_per_prio *per_prio; enum dd_prio prio; + int fifo_expire; lockdep_assert_held(&dd->lock); @@ -840,7 +842,9 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, /* * set expire time and add to fifo list */ - rq->fifo_time = jiffies + dd->fifo_expire[data_dir]; + fifo_expire = task_is_realtime(current) ? dd->fifo_expire[data_dir] : + CFS_PROPORTION(current, dd->fifo_expire[data_dir]); + rq->fifo_time = jiffies + fifo_expire; insert_before = &per_prio->fifo_list[data_dir]; #ifdef CONFIG_BLK_DEV_ZONED /* -- 2.25.1
