Commit fa6fb5aa authored by Shaohua Li's avatar Shaohua Li Committed by Jens Axboe
Browse files

blk-throttle: ignore idle cgroup limit 



Last patch introduces a way to detect idle cgroup. We use it to make
upgrade/downgrade decision. And the new algorithm can detect completely
idle cgroup too, so we can delete the corresponding code.

Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent ada75b6e

block/blk-throttle.c

+26 −14
Original line number Diff line number Diff line
@@ -152,8 +152,6 @@ struct throtl_grp { 


	unsigned long last_check_time;



	unsigned long last_dispatch_time[2];



	/* When did we start a new slice */

	unsigned long slice_start[2];

	unsigned long slice_end[2];
@@ -508,8 +506,6 @@ static void throtl_pd_online(struct blkg_policy_data *pd) 
	 * Update has_rules[] after a new group is brought online.

	 */

	tg_update_has_rules(tg);

	tg->last_dispatch_time[READ] = jiffies;

	tg->last_dispatch_time[WRITE] = jiffies;

}



static void blk_throtl_update_limit_valid(struct throtl_data *td)
@@ -1708,9 +1704,8 @@ static bool throtl_tg_can_upgrade(struct throtl_grp *tg) 
		return true;



	if (time_after_eq(jiffies,

	     tg->last_dispatch_time[READ] + tg->td->throtl_slice) &&

	    time_after_eq(jiffies,

	     tg->last_dispatch_time[WRITE] + tg->td->throtl_slice))

		tg_last_low_overflow_time(tg) + tg->td->throtl_slice) &&

	    throtl_tg_is_idle(tg))

		return true;

	return false;

}
@@ -1756,6 +1751,26 @@ static bool throtl_can_upgrade(struct throtl_data *td, 
	return true;

}



static void throtl_upgrade_check(struct throtl_grp *tg)

{

	unsigned long now = jiffies;



	if (tg->td->limit_index != LIMIT_LOW)

		return;



	if (time_after(tg->last_check_time + tg->td->throtl_slice, now))

		return;



	tg->last_check_time = now;



	if (!time_after_eq(now,

	     __tg_last_low_overflow_time(tg) + tg->td->throtl_slice))

		return;



	if (throtl_can_upgrade(tg->td, NULL))

		throtl_upgrade_state(tg->td);

}



static void throtl_upgrade_state(struct throtl_data *td)

{

	struct cgroup_subsys_state *pos_css;
@@ -1797,18 +1812,15 @@ static bool throtl_tg_can_downgrade(struct throtl_grp *tg) 
	struct throtl_data *td = tg->td;

	unsigned long now = jiffies;



	if (time_after_eq(now, tg->last_dispatch_time[READ] +

					td->throtl_slice) &&

	    time_after_eq(now, tg->last_dispatch_time[WRITE] +

					td->throtl_slice))

		return false;

	/*

	 * If cgroup is below low limit, consider downgrade and throttle other

	 * cgroups

	 */

	if (time_after_eq(now, td->low_upgrade_time + td->throtl_slice) &&

	    time_after_eq(now, tg_last_low_overflow_time(tg) +

					td->throtl_slice))

					td->throtl_slice) &&

	    (!throtl_tg_is_idle(tg) ||

	     !list_empty(&tg_to_blkg(tg)->blkcg->css.children)))

		return true;

	return false;

}
@@ -1931,10 +1943,10 @@ bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg, 


again:

	while (true) {

		tg->last_dispatch_time[rw] = jiffies;

		if (tg->last_low_overflow_time[rw] == 0)

			tg->last_low_overflow_time[rw] = jiffies;

		throtl_downgrade_check(tg);

		throtl_upgrade_check(tg);

		/* throtl is FIFO - if bios are already queued, should queue */

		if (sq->nr_queued[rw])

			break;

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