diff options
| author | Alan D. Brunelle <Alan.Brunelle@hp.com> | 2010-01-29 09:04:08 +0100 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2010-01-29 09:04:08 +0100 |
| commit | 488991e28e55b4fbca8067edf0259f69d1a6f92c (patch) | |
| tree | fea5e0aca42e338137cc050e66aaeb5f539e3d21 /include/linux/blkdev.h | |
| parent | 47483e25205f1f8d79784f0f7c733941bc080ec0 (diff) | |
block: Added in stricter no merge semantics for block I/O
Updated 'nomerges' tunable to accept a value of '2' - indicating that _no_
merges at all are to be attempted (not even the simple one-hit cache).
The following table illustrates the additional benefit - 5 minute runs of
a random I/O load were applied to a dozen devices on a 16-way x86_64 system.
nomerges Throughput %System Improvement (tput / %sys)
-------- ------------ ----------- -------------------------
0 12.45 MB/sec 0.669365609
1 12.50 MB/sec 0.641519199 0.40% / 2.71%
2 12.52 MB/sec 0.639849750 0.56% / 2.96%
Signed-off-by: Alan D. Brunelle <alan.brunelle@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'include/linux/blkdev.h')
| -rw-r--r-- | include/linux/blkdev.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index ffb13ad3571..f71f5c58620 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -463,6 +463,7 @@ struct request_queue #define QUEUE_FLAG_IO_STAT 15 /* do IO stats */ #define QUEUE_FLAG_CQ 16 /* hardware does queuing */ #define QUEUE_FLAG_DISCARD 17 /* supports DISCARD */ +#define QUEUE_FLAG_NOXMERGES 18 /* No extended merges */ #define QUEUE_FLAG_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \ (1 << QUEUE_FLAG_CLUSTER) | \ @@ -589,6 +590,8 @@ enum { #define blk_queue_queuing(q) test_bit(QUEUE_FLAG_CQ, &(q)->queue_flags) #define blk_queue_stopped(q) test_bit(QUEUE_FLAG_STOPPED, &(q)->queue_flags) #define blk_queue_nomerges(q) test_bit(QUEUE_FLAG_NOMERGES, &(q)->queue_flags) +#define blk_queue_noxmerges(q) \ + test_bit(QUEUE_FLAG_NOXMERGES, &(q)->queue_flags) #define blk_queue_nonrot(q) test_bit(QUEUE_FLAG_NONROT, &(q)->queue_flags) #define blk_queue_io_stat(q) test_bit(QUEUE_FLAG_IO_STAT, &(q)->queue_flags) #define blk_queue_flushing(q) ((q)->ordseq) |