Set the QUEUE_FLAG_NOWAIT. 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 (pmem-nowait-on) # grep IOPS pmem*fio | column -t
pmem-nowait-off-1.fio: read: IOPS=3683k, BW=14.0GiB/s
pmem-nowait-off-2.fio: read: IOPS=3819k, BW=14.6GiB/s
pmem-nowait-off-3.fio: read: IOPS=3999k, BW=15.3GiB/s
pmem-nowait-on-1.fio: read: IOPS=5837k, BW=22.3GiB/s
pmem-nowait-on-2.fio: read: IOPS=5936k, BW=22.6GiB/s
pmem-nowait-on-3.fio: read: IOPS=5945k, BW=22.7GiB/s
linux-block (pmem-nowait-on) # grep cpu pmem*fio | column -t
pmem-nowait-off-1.fio: cpu : usr=7.09%, sys=29.65%, ctx=198742065
pmem-nowait-off-2.fio: cpu : usr=6.89%, sys=30.56%, ctx=205817652
pmem-nowait-off-3.fio: cpu : usr=6.86%, sys=30.94%, ctx=222627094
pmem-nowait-on-1.fio: cpu : usr=10.58%, sys=88.44%, ctx=27181
pmem-nowait-on-2.fio: cpu : usr=10.50%, sys=87.75%, ctx=25746
pmem-nowait-on-3.fio: cpu : usr=10.67%, sys=88.60%, ctx=28261
linux-block (pmem-nowait-on) # grep slat pmem*fio | column -t
pmem-nowait-off-1.fio: slat (nsec): min=432, max=50847k, avg=9324.69
pmem-nowait-off-2.fio: slat (nsec): min=441, max=52557k, avg=9132.45
pmem-nowait-off-3.fio: slat (nsec): min=430, max=36113k, avg=9132.63
pmem-nowait-on-1.fio: slat (nsec): min=1393, max=68090k, avg=7615.31
pmem-nowait-on-2.fio: slat (nsec): min=1222, max=44137k, avg=7493.77
pmem-nowait-on-3.fio: slat (nsec): min=1493, max=40100k, avg=7486.36
Signed-off-by: Chaitanya Kulkarni <k...@nvidia.com>
---
drivers/nvdimm/pmem.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
index 46e094e56159..ddd485c377eb 100644
--- a/drivers/nvdimm/pmem.c
+++ b/drivers/nvdimm/pmem.c
@@ -543,6 +543,7 @@ static int pmem_attach_disk(struct device *dev,
blk_queue_max_hw_sectors(q, UINT_MAX);
blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
blk_queue_flag_set(QUEUE_FLAG_SYNCHRONOUS, q);
+ blk_queue_flag_set(QUEUE_FLAG_NOWAIT, q);
if (pmem->pfn_flags & PFN_MAP)
blk_queue_flag_set(QUEUE_FLAG_DAX, q);
--
2.40.0
