Commit 681cd46f authored by Yu Kuai's avatar Yu Kuai Committed by Jens Axboe
Browse files

blk-throttle: factor out code to calculate ios/bytes_allowed 



No functional changes, new apis will be used in later patches to
calculate wait time for throttled bios when new configuration is
submitted.

Noted this patch also rename tg_with_in_iops/bps_limit() to
tg_within_iops/bps_limit().

Signed-off-by: default avatarYu Kuai <yukuai3@huawei.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220829022240.3348319-4-yukuai1@huaweicloud.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 8d6bbaad

block/blk-throttle.c

+35 −24
Original line number Diff line number Diff line
@@ -754,33 +754,20 @@ static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw) 
		   tg->slice_start[rw], tg->slice_end[rw], jiffies);

}



static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,

				  u32 iops_limit, unsigned long *wait)

static unsigned int calculate_io_allowed(u32 iops_limit,

					 unsigned long jiffy_elapsed)

{

	bool rw = bio_data_dir(bio);

	unsigned int io_allowed;

	unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;

	u64 tmp;



	if (iops_limit == UINT_MAX) {

		if (wait)

			*wait = 0;

		return true;

	}



	jiffy_elapsed = jiffies - tg->slice_start[rw];



	/* Round up to the next throttle slice, wait time must be nonzero */

	jiffy_elapsed_rnd = roundup(jiffy_elapsed + 1, tg->td->throtl_slice);



	/*

	 * jiffy_elapsed_rnd should not be a big value as minimum iops can be

	 * jiffy_elapsed should not be a big value as minimum iops can be

	 * 1 then at max jiffy elapsed should be equivalent of 1 second as we

	 * will allow dispatch after 1 second and after that slice should

	 * have been trimmed.

	 */



	tmp = (u64)iops_limit * jiffy_elapsed_rnd;

	tmp = (u64)iops_limit * jiffy_elapsed;

	do_div(tmp, HZ);



	if (tmp > UINT_MAX)
@@ -788,6 +775,32 @@ static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio, 
	else

		io_allowed = tmp;



	return io_allowed;

}



static u64 calculate_bytes_allowed(u64 bps_limit, unsigned long jiffy_elapsed)

{

	return mul_u64_u64_div_u64(bps_limit, (u64)jiffy_elapsed, (u64)HZ);

}



static bool tg_within_iops_limit(struct throtl_grp *tg, struct bio *bio,

				 u32 iops_limit, unsigned long *wait)

{

	bool rw = bio_data_dir(bio);

	unsigned int io_allowed;

	unsigned long jiffy_elapsed, jiffy_wait, jiffy_elapsed_rnd;



	if (iops_limit == UINT_MAX) {

		if (wait)

			*wait = 0;

		return true;

	}



	jiffy_elapsed = jiffies - tg->slice_start[rw];



	/* Round up to the next throttle slice, wait time must be nonzero */

	jiffy_elapsed_rnd = roundup(jiffy_elapsed + 1, tg->td->throtl_slice);

	io_allowed = calculate_io_allowed(iops_limit, jiffy_elapsed_rnd);

	if (tg->io_disp[rw] + 1 <= io_allowed) {

		if (wait)

			*wait = 0;
@@ -802,7 +815,7 @@ static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio, 
	return false;

}



static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,

static bool tg_within_bps_limit(struct throtl_grp *tg, struct bio *bio,

				u64 bps_limit, unsigned long *wait)

{

	bool rw = bio_data_dir(bio);
@@ -824,9 +837,7 @@ static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio, 
		jiffy_elapsed_rnd = tg->td->throtl_slice;



	jiffy_elapsed_rnd = roundup(jiffy_elapsed_rnd, tg->td->throtl_slice);

	bytes_allowed = mul_u64_u64_div_u64(bps_limit, (u64)jiffy_elapsed_rnd,

					    (u64)HZ);



	bytes_allowed = calculate_bytes_allowed(bps_limit, jiffy_elapsed_rnd);

	if (tg->bytes_disp[rw] + bio_size <= bytes_allowed) {

		if (wait)

			*wait = 0;
@@ -895,8 +906,8 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio, 
				jiffies + tg->td->throtl_slice);

	}



	if (tg_with_in_bps_limit(tg, bio, bps_limit, &bps_wait) &&

	    tg_with_in_iops_limit(tg, bio, iops_limit, &iops_wait)) {

	if (tg_within_bps_limit(tg, bio, bps_limit, &bps_wait) &&

	    tg_within_iops_limit(tg, bio, iops_limit, &iops_wait)) {

		if (wait)

			*wait = 0;

		return true;