Commit d61fcfa4 authored by Shaohua Li's avatar Shaohua Li Committed by Jens Axboe
Browse files

blk-throttle: choose a small throtl_slice for SSD 



The throtl_slice is 100ms by default. This is a long time for SSD, a lot
of IO can run. To make cgroups have smoother throughput, we choose a
small value (20ms) for SSD.

Signed-off-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 297e3d85

block/blk-sysfs.c

+2 −0
Original line number Diff line number Diff line
@@ -906,6 +906,8 @@ int blk_register_queue(struct gendisk *disk) 


	blk_wb_init(q);



	blk_throtl_register_queue(q);



	if (q->request_fn || (q->mq_ops && q->elevator)) {

		ret = elv_register_queue(q);

		if (ret) {

block/blk-throttle.c

+20 −3
Original line number Diff line number Diff line
@@ -18,8 +18,9 @@ static int throtl_grp_quantum = 8; 
/* Total max dispatch from all groups in one round */

static int throtl_quantum = 32;



/* Throttling is performed over 100ms slice and after that slice is renewed */

#define DFL_THROTL_SLICE (HZ / 10)

/* Throttling is performed over a slice and after that slice is renewed */

#define DFL_THROTL_SLICE_HD (HZ / 10)

#define DFL_THROTL_SLICE_SSD (HZ / 50)

#define MAX_THROTL_SLICE (HZ)



static struct blkcg_policy blkcg_policy_throtl;
@@ -1961,7 +1962,6 @@ int blk_throtl_init(struct request_queue *q) 


	q->td = td;

	td->queue = q;

	td->throtl_slice = DFL_THROTL_SLICE;



	td->limit_valid[LIMIT_MAX] = true;

	td->limit_index = LIMIT_MAX;
@@ -1982,6 +1982,23 @@ void blk_throtl_exit(struct request_queue *q) 
	kfree(q->td);

}



void blk_throtl_register_queue(struct request_queue *q)

{

	struct throtl_data *td;



	td = q->td;

	BUG_ON(!td);



	if (blk_queue_nonrot(q))

		td->throtl_slice = DFL_THROTL_SLICE_SSD;

	else

		td->throtl_slice = DFL_THROTL_SLICE_HD;

#ifndef CONFIG_BLK_DEV_THROTTLING_LOW

	/* if no low limit, use previous default */

	td->throtl_slice = DFL_THROTL_SLICE_HD;

#endif

}



#ifdef CONFIG_BLK_DEV_THROTTLING_LOW

ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page)

{

block/blk.h

+2 −0
Original line number Diff line number Diff line
@@ -319,10 +319,12 @@ static inline struct io_context *create_io_context(gfp_t gfp_mask, int node) 
extern void blk_throtl_drain(struct request_queue *q);

extern int blk_throtl_init(struct request_queue *q);

extern void blk_throtl_exit(struct request_queue *q);

extern void blk_throtl_register_queue(struct request_queue *q);

#else /* CONFIG_BLK_DEV_THROTTLING */

static inline void blk_throtl_drain(struct request_queue *q) { }

static inline int blk_throtl_init(struct request_queue *q) { return 0; }

static inline void blk_throtl_exit(struct request_queue *q) { }

static inline void blk_throtl_register_queue(struct request_queue *q) { }

#endif /* CONFIG_BLK_DEV_THROTTLING */

#ifdef CONFIG_BLK_DEV_THROTTLING_LOW

extern ssize_t blk_throtl_sample_time_show(struct request_queue *q, char *page);

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