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authorShaohua Li <shli@fb.com>2015-01-16 04:32:25 +0300
committerJens Axboe <axboe@fb.com>2015-01-24 00:15:46 +0300
commitee1b6f7aff94019c09e73837054979063f722046 (patch)
tree79c7b943d7c6d62fec1874afd2c50964de054aa0 /include
parentbb5c3cdda37aad22996d6da2addd58cadc0436c0 (diff)
downloadlinux-ee1b6f7aff94019c09e73837054979063f722046.tar.xz
block: support different tag allocation policy
The libata tag allocation is using a round-robin policy. Next patch will make libata use block generic tag allocation, so let's add a policy to tag allocation. Currently two policies: FIFO (default) and round-robin. Cc: Jens Axboe <axboe@fb.com> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include')
-rw-r--r--include/linux/blkdev.h8
-rw-r--r--include/scsi/scsi_host.h3
-rw-r--r--include/scsi/scsi_tcq.h3
3 files changed, 11 insertions, 3 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4c4b732d7556..6f388fd1c11c 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -272,7 +272,11 @@ struct blk_queue_tag {
int max_depth; /* what we will send to device */
int real_max_depth; /* what the array can hold */
atomic_t refcnt; /* map can be shared */
+ int alloc_policy; /* tag allocation policy */
+ int next_tag; /* next tag */
};
+#define BLK_TAG_ALLOC_FIFO 0 /* allocate starting from 0 */
+#define BLK_TAG_ALLOC_RR 1 /* allocate starting from last allocated tag */
#define BLK_SCSI_MAX_CMDS (256)
#define BLK_SCSI_CMD_PER_LONG (BLK_SCSI_MAX_CMDS / (sizeof(long) * 8))
@@ -1139,11 +1143,11 @@ static inline bool blk_needs_flush_plug(struct task_struct *tsk)
extern int blk_queue_start_tag(struct request_queue *, struct request *);
extern struct request *blk_queue_find_tag(struct request_queue *, int);
extern void blk_queue_end_tag(struct request_queue *, struct request *);
-extern int blk_queue_init_tags(struct request_queue *, int, struct blk_queue_tag *);
+extern int blk_queue_init_tags(struct request_queue *, int, struct blk_queue_tag *, int);
extern void blk_queue_free_tags(struct request_queue *);
extern int blk_queue_resize_tags(struct request_queue *, int);
extern void blk_queue_invalidate_tags(struct request_queue *);
-extern struct blk_queue_tag *blk_init_tags(int);
+extern struct blk_queue_tag *blk_init_tags(int, int);
extern void blk_free_tags(struct blk_queue_tag *);
static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 019e66858ce6..e113c757d555 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -402,6 +402,9 @@ struct scsi_host_template {
*/
unsigned char present;
+ /* If use block layer to manage tags, this is tag allocation policy */
+ int tag_alloc_policy;
+
/*
* Let the block layer assigns tags to all commands.
*/
diff --git a/include/scsi/scsi_tcq.h b/include/scsi/scsi_tcq.h
index 9708b28bd2aa..b27977e8aaed 100644
--- a/include/scsi/scsi_tcq.h
+++ b/include/scsi/scsi_tcq.h
@@ -66,7 +66,8 @@ static inline int scsi_init_shared_tag_map(struct Scsi_Host *shost, int depth)
* devices on the shared host (for libata)
*/
if (!shost->bqt) {
- shost->bqt = blk_init_tags(depth);
+ shost->bqt = blk_init_tags(depth,
+ shost->hostt->tag_alloc_policy);
if (!shost->bqt)
return -ENOMEM;
}