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scsi: target: Convert target drivers to use sbitmap

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The sbitmap and the percpu_ida perform essentially the same task,
allocating tags for commands.  The sbitmap outperforms the percpu_ida as
documented here: https://lkml.org/lkml/2014/4/22/553

The sbitmap interface is a little harder to use, but being able to remove
the percpu_ida code and getting better performance justifies the additional
complexity.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>	# f_tcm
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Matthew Wilcox
2018-06-12 12:05:44 -07:00
committed by Martin K. Petersen
parent 83c2b54b92
commit 10e9cbb6b5
10 changed files with 59 additions and 24 deletions
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7
include/target/target_core_base.h
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@@ -4,7 +4,7 @@
#include <linux/configfs.h> /* struct config_group */
#include <linux/dma-direction.h> /* enum dma_data_direction */
#include <linux/percpu_ida.h> /* struct percpu_ida */
#include <linux/sbitmap.h>
#include <linux/percpu-refcount.h>
#include <linux/semaphore.h> /* struct semaphore */
#include <linux/completion.h>
@@ -455,6 +455,7 @@ struct se_cmd {
int sam_task_attr;
/* Used for se_sess->sess_tag_pool */
unsigned int map_tag;
int map_cpu;
/* Transport protocol dependent state, see transport_state_table */
enum transport_state_table t_state;
/* See se_cmd_flags_table */
@@ -608,7 +609,7 @@ struct se_session {
struct list_head sess_wait_list;
spinlock_t sess_cmd_lock;
void *sess_cmd_map;
struct percpu_ida sess_tag_pool;
struct sbitmap_queue sess_tag_pool;
};
struct se_device;
@@ -936,7 +937,7 @@ static inline void atomic_dec_mb(atomic_t *v)
static inline void target_free_tag(struct se_session *sess, struct se_cmd *cmd)
{
percpu_ida_free(&sess->sess_tag_pool, cmd->map_tag);
sbitmap_queue_clear(&sess->sess_tag_pool, cmd->map_tag, cmd->map_cpu);
}
#endif /* TARGET_CORE_BASE_H */