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Commit d62118b6 authored by Jens Axboe's avatar Jens Axboe
Browse files

blk-wbt: allow wbt to be enabled always through sysfs 



Currently there's no way to enable wbt if it's not enabled in the
kernel config by default for a device. Allow a write to the
'wbt_lat_usec' queue sysfs file to enable wbt.

This is useful for both the kernel config case, but also if the
device is CFQ managed and it was turned off by default.

Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent fa224eed

block/blk-sysfs.c

+16 −6
Original line number Diff line number Diff line
@@ -425,20 +425,30 @@ static ssize_t queue_wb_lat_store(struct request_queue *q, const char *page, 
	ssize_t ret;

	s64 val;



	rwb = q->rq_wb;

	if (!rwb)

		return -EINVAL;



	ret = queue_var_store64(&val, page);

	if (ret < 0)

		return ret;

	if (val < -1)

		return -EINVAL;



	rwb = q->rq_wb;

	if (!rwb) {

		ret = wbt_init(q);

		if (ret)

			return ret;



		rwb = q->rq_wb;

		if (!rwb)

			return -EINVAL;

	}



	if (val == -1)

		rwb->min_lat_nsec = wbt_default_latency_nsec(q);

	else if (val >= 0)

		rwb->min_lat_nsec = val * 1000ULL;

	else

		return -EINVAL;



	if (rwb->enable_state == WBT_STATE_ON_DEFAULT)

		rwb->enable_state = WBT_STATE_ON_MANUAL;



	wbt_update_limits(rwb);

	return count;

block/blk-wbt.c

+2 −1
Original line number Diff line number Diff line
@@ -673,7 +673,7 @@ void wbt_disable_default(struct request_queue *q) 
{

	struct rq_wb *rwb = q->rq_wb;



	if (rwb) {

	if (rwb && rwb->enable_state == WBT_STATE_ON_DEFAULT) {

		del_timer_sync(&rwb->window_timer);

		rwb->win_nsec = rwb->min_lat_nsec = 0;

		wbt_update_limits(rwb);
@@ -721,6 +721,7 @@ int wbt_init(struct request_queue *q) 
	rwb->last_comp = rwb->last_issue = jiffies;

	rwb->queue = q;

	rwb->win_nsec = RWB_WINDOW_NSEC;

	rwb->enable_state = WBT_STATE_ON_DEFAULT;

	wbt_update_limits(rwb);



	/*

block/blk-wbt.h

+11 −0
Original line number Diff line number Diff line
@@ -21,6 +21,15 @@ enum { 
	WBT_NUM_RWQ		= 2,

};



/*

 * Enable states. Either off, or on by default (done at init time),

 * or on through manual setup in sysfs.

 */

enum {

	WBT_STATE_ON_DEFAULT	= 1,

	WBT_STATE_ON_MANUAL	= 2,

};



static inline void wbt_clear_state(struct blk_issue_stat *stat)

{

	stat->time &= BLK_STAT_TIME_MASK;
@@ -61,6 +70,8 @@ struct rq_wb { 
	int scale_step;

	bool scaled_max;



	short enable_state;			/* WBT_STATE_* */



	/*

	 * Number of consecutive periods where we don't have enough

	 * information to make a firm scale up/down decision.