[PATCH 1/1] bcache: allow user to set QUEUE_FLAG_NOWAIT

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


Allow user to set the QUEUE_FLAG_NOWAIT optionally using module
parameter to retain the default behaviour. Also, update respective
allocation flags in the write path. Following are the performance
numbers with io_uring fio engine for random read, note that device has
been populated fully with randwrite workload before taking these
numbers :-

* linux-block (for-next) # grep IOPS  bc-*fio | column -t

nowait-off-1.fio:  read:  IOPS=482k,  BW=1885MiB/s
nowait-off-2.fio:  read:  IOPS=484k,  BW=1889MiB/s
nowait-off-3.fio:  read:  IOPS=483k,  BW=1886MiB/s

nowait-on-1.fio:   read:  IOPS=544k,  BW=2125MiB/s
nowait-on-2.fio:   read:  IOPS=547k,  BW=2137MiB/s
nowait-on-3.fio:   read:  IOPS=546k,  BW=2132MiB/s

* linux-block (for-next) # grep slat  bc-*fio | column -t

nowait-off-1.fio: slat (nsec):  min=430, max=5488.5k, avg=2797.52
nowait-off-2.fio: slat (nsec):  min=431, max=8252.4k, avg=2805.33
nowait-off-3.fio: slat (nsec):  min=431, max=6846.6k, avg=2814.57

nowait-on-1.fio:  slat (usec):  min=2,   max=39086,   avg=87.48
nowait-on-2.fio:  slat (usec):  min=3,   max=39519,   avg=86.98
nowait-on-3.fio:  slat (usec):  min=3,   max=38880,   avg=87.17

* linux-block (for-next) # grep cpu  bc-*fio | column -t

nowait-off-1.fio:  cpu  :  usr=2.77%,  sys=6.57%,   ctx=22015526
nowait-off-2.fio:  cpu  :  usr=2.75%,  sys=6.59%,   ctx=22003700
nowait-off-3.fio:  cpu  :  usr=2.81%,  sys=6.57%,   ctx=21938309

nowait-on-1.fio:   cpu  :  usr=1.08%,  sys=78.39%,  ctx=2744092
nowait-on-2.fio:   cpu  :  usr=1.10%,  sys=79.76%,  ctx=2537466
nowait-on-3.fio:   cpu  :  usr=1.10%,  sys=79.88%,  ctx=2528092

Signed-off-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
 drivers/md/bcache/request.c | 3 ++-
 drivers/md/bcache/super.c   | 6 ++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 67a2e29e0b40..2055a23eb4b7 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -716,9 +716,10 @@ static inline struct search *search_alloc(struct bio *bio,
 		struct bcache_device *d, struct block_device *orig_bdev,
 		unsigned long start_time)
+	gfp_t gfp = bio->bi_opf & REQ_NOWAIT ? GFP_NOWAIT : GFP_NOIO;
 	struct search *s;
-	s = mempool_alloc(&d->c->search, GFP_NOIO);
+	s = mempool_alloc(&d->c->search, gfp);
 	closure_init(&s->cl, NULL);
 	do_bio_hook(s, bio, request_endio);
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 7e9d19fd21dd..f76822bece26 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -28,6 +28,7 @@
 unsigned int bch_cutoff_writeback;
 unsigned int bch_cutoff_writeback_sync;
+bool bch_nowait;
 static const char bcache_magic[] = {
 	0xc6, 0x85, 0x73, 0xf6, 0x4e, 0x1a, 0x45, 0xca,
@@ -971,6 +972,8 @@ static int bcache_device_init(struct bcache_device *d, unsigned int block_size,
 	blk_queue_flag_set(QUEUE_FLAG_NONROT, d->disk->queue);
+	if (bch_nowait)
+		blk_queue_flag_set(QUEUE_FLAG_NOWAIT, d->disk->queue);
 	blk_queue_write_cache(q, true, true);
@@ -2933,6 +2936,9 @@ MODULE_PARM_DESC(bch_cutoff_writeback, "threshold to cutoff writeback");
 module_param(bch_cutoff_writeback_sync, uint, 0);
 MODULE_PARM_DESC(bch_cutoff_writeback_sync, "hard threshold to cutoff writeback");
+module_param(bch_nowait, bool, 0);
 MODULE_DESCRIPTION("Bcache: a Linux block layer cache");
 MODULE_AUTHOR("Kent Overstreet <kent.overstreet@xxxxxxxxx>");

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Linux ARM Kernel]     [Linux Filesystem Development]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux OMAP]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux