linux_dsm_epyc7002/include
Ming Lei 6eb045e092 scsi: core: avoid host-wide host_busy counter for scsi_mq
It isn't necessary to check the host depth in scsi_queue_rq() any more
since it has been respected by blk-mq before calling scsi_queue_rq() via
getting driver tag.

Lots of LUNs may attach to same host and per-host IOPS may reach millions,
so we should avoid expensive atomic operations on the host-wide counter in
the IO path.

This patch implements scsi_host_busy() via blk_mq_tagset_busy_iter() with
one scsi command state for reading the count of busy IOs for scsi_mq.

It is observed that IOPS is increased by 15% in IO test on scsi_debug (32
LUNs, 32 submit queues, 1024 can_queue, libaio/dio) in a dual-socket
system.

Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Omar Sandoval <osandov@fb.com>,
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
Cc: James Bottomley <james.bottomley@hansenpartnership.com>,
Cc: Christoph Hellwig <hch@lst.de>,
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20191025065855.6309-1-ming.lei@redhat.com
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2019-11-01 20:12:50 -04:00
..
acpi
asm-generic Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
clocksource
crypto Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity 2019-09-27 19:37:27 -07:00
drm drm: Measure Self Refresh Entry/Exit times to avoid thrashing 2019-09-19 10:03:32 -04:00
dt-bindings Main MIPS changes for v5.4: 2019-09-22 09:30:30 -07:00
keys
kvm
linux libnvdimm fixes v5.4-rc1 2019-09-29 10:33:41 -07:00
math-emu
media
misc
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf 2019-09-27 20:15:00 +02:00
pcmcia
ras
rdma RDMA subsystem updates for 5.4 2019-09-21 10:26:24 -07:00
scsi scsi: core: avoid host-wide host_busy counter for scsi_mq 2019-11-01 20:12:50 -04:00
soc
sound
target scsi: target: Remove tpg_list and se_portal_group.se_tpg_node 2019-10-03 22:00:09 -04:00
trace A few more tracing fixes: 2019-09-30 09:29:53 -07:00
uapi scsi: ch: add include guard to chio.h 2019-10-09 22:31:14 -04:00
vdso
video
xen
Kbuild - New Drivers 2019-09-23 19:37:49 -07:00