Commit bf2c4282 authored by Ming Lei's avatar Ming Lei Committed by Martin K. Petersen
Browse files

scsi: sbitmap: Add helpers for updating allocation hint 

Add helpers for updating allocation hint so that we can avoid duplicate
code.

Prepare for moving allocation hint into sbitmap.

Link: https://lore.kernel.org/r/20210122023317.687987-4-ming.lei@redhat.com


Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Tested-by: default avatarSumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.de>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent efe1f3a1

lib/sbitmap.c

+54 −39
Original line number Diff line number Diff line
@@ -9,6 +9,55 @@ 
#include <linux/sbitmap.h>

#include <linux/seq_file.h>



static int init_alloc_hint(struct sbitmap_queue *sbq, gfp_t flags)

{

	unsigned depth = sbq->sb.depth;



	sbq->alloc_hint = alloc_percpu_gfp(unsigned int, flags);

	if (!sbq->alloc_hint)

		return -ENOMEM;



	if (depth && !sbq->sb.round_robin) {

		int i;



		for_each_possible_cpu(i)

			*per_cpu_ptr(sbq->alloc_hint, i) = prandom_u32() % depth;

	}



	return 0;

}



static inline unsigned update_alloc_hint_before_get(struct sbitmap_queue *sbq,

						    unsigned int depth)

{

	unsigned hint;



	hint = this_cpu_read(*sbq->alloc_hint);

	if (unlikely(hint >= depth)) {

		hint = depth ? prandom_u32() % depth : 0;

		this_cpu_write(*sbq->alloc_hint, hint);

	}



	return hint;

}



static inline void update_alloc_hint_after_get(struct sbitmap_queue *sbq,

					       unsigned int depth,

					       unsigned int hint,

					       unsigned int nr)

{

	if (nr == -1) {

		/* If the map is full, a hint won't do us much good. */

		this_cpu_write(*sbq->alloc_hint, 0);

	} else if (nr == hint || unlikely(sbq->sb.round_robin)) {

		/* Only update the hint if we used it. */

		hint = nr + 1;

		if (hint >= depth - 1)

			hint = 0;

		this_cpu_write(*sbq->alloc_hint, hint);

	}

}



/*

 * See if we have deferred clears that we can batch move

 */
@@ -355,17 +404,11 @@ int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth, 
	if (ret)

		return ret;



	sbq->alloc_hint = alloc_percpu_gfp(unsigned int, flags);

	if (!sbq->alloc_hint) {

	if (init_alloc_hint(sbq, flags) != 0) {

		sbitmap_free(&sbq->sb);

		return -ENOMEM;

	}



	if (depth && !round_robin) {

		for_each_possible_cpu(i)

			*per_cpu_ptr(sbq->alloc_hint, i) = prandom_u32() % depth;

	}



	sbq->min_shallow_depth = UINT_MAX;

	sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);

	atomic_set(&sbq->wake_index, 0);
@@ -418,24 +461,10 @@ int __sbitmap_queue_get(struct sbitmap_queue *sbq) 
	unsigned int hint, depth;

	int nr;



	hint = this_cpu_read(*sbq->alloc_hint);

	depth = READ_ONCE(sbq->sb.depth);

	if (unlikely(hint >= depth)) {

		hint = depth ? prandom_u32() % depth : 0;

		this_cpu_write(*sbq->alloc_hint, hint);

	}

	hint = update_alloc_hint_before_get(sbq, depth);

	nr = sbitmap_get(&sbq->sb, hint);



	if (nr == -1) {

		/* If the map is full, a hint won't do us much good. */

		this_cpu_write(*sbq->alloc_hint, 0);

	} else if (nr == hint || unlikely(sbq->sb.round_robin)) {

		/* Only update the hint if we used it. */

		hint = nr + 1;

		if (hint >= depth - 1)

			hint = 0;

		this_cpu_write(*sbq->alloc_hint, hint);

	}

	update_alloc_hint_after_get(sbq, depth, hint, nr);



	return nr;

}
@@ -449,24 +478,10 @@ int __sbitmap_queue_get_shallow(struct sbitmap_queue *sbq, 


	WARN_ON_ONCE(shallow_depth < sbq->min_shallow_depth);



	hint = this_cpu_read(*sbq->alloc_hint);

	depth = READ_ONCE(sbq->sb.depth);

	if (unlikely(hint >= depth)) {

		hint = depth ? prandom_u32() % depth : 0;

		this_cpu_write(*sbq->alloc_hint, hint);

	}

	hint = update_alloc_hint_before_get(sbq, depth);

	nr = sbitmap_get_shallow(&sbq->sb, hint, shallow_depth);



	if (nr == -1) {

		/* If the map is full, a hint won't do us much good. */

		this_cpu_write(*sbq->alloc_hint, 0);

	} else if (nr == hint || unlikely(sbq->sb.round_robin)) {

		/* Only update the hint if we used it. */

		hint = nr + 1;

		if (hint >= depth - 1)

			hint = 0;

		this_cpu_write(*sbq->alloc_hint, hint);

	}

	update_alloc_hint_after_get(sbq, depth, hint, nr);



	return nr;

}