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| author | Jens Axboe <jens.axboe@oracle.com> | 2009-05-20 08:54:31 +0200 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2009-05-20 08:54:31 +0200 |
| commit | 0a7ae2ff0d29bb3b327edff4c8ab67b3834fa811 (patch) | |
| tree | 88309ac99a39e15b9b23525a00a15b1564957b32 /block/blk-tag.c | |
| parent | ac36552a52a6ec8563ac0a109e2a0935673f4abb (diff) | |
| download | linux-0a7ae2ff0d29bb3b327edff4c8ab67b3834fa811.tar.gz linux-0a7ae2ff0d29bb3b327edff4c8ab67b3834fa811.tar.bz2 linux-0a7ae2ff0d29bb3b327edff4c8ab67b3834fa811.zip | |
block: change the tag sync vs async restriction logic
Make them fully share the tag space, but disallow async requests using
the last any two slots.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/blk-tag.c')
| -rw-r--r-- | block/blk-tag.c | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/block/blk-tag.c b/block/blk-tag.c index c260f7c30dda..2e5cfeb59333 100644 --- a/block/blk-tag.c +++ b/block/blk-tag.c @@ -336,7 +336,7 @@ EXPORT_SYMBOL(blk_queue_end_tag); int blk_queue_start_tag(struct request_queue *q, struct request *rq) { struct blk_queue_tag *bqt = q->queue_tags; - unsigned max_depth, offset; + unsigned max_depth; int tag; if (unlikely((rq->cmd_flags & REQ_QUEUED))) { @@ -355,13 +355,16 @@ int blk_queue_start_tag(struct request_queue *q, struct request *rq) * to starve sync IO on behalf of flooding async IO. */ max_depth = bqt->max_depth; - if (rq_is_sync(rq)) - offset = 0; - else - offset = max_depth >> 2; + if (!rq_is_sync(rq) && max_depth > 1) { + max_depth -= 2; + if (!max_depth) + max_depth = 1; + if (q->in_flight[0] > max_depth) + return 1; + } do { - tag = find_next_zero_bit(bqt->tag_map, max_depth, offset); + tag = find_first_zero_bit(bqt->tag_map, max_depth); if (tag >= max_depth) return 1; |