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| author | Ming Lei <ming.lei@redhat.com> | 2021-01-22 10:33:17 +0800 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2021-03-04 17:37:00 -0500 |
| commit | 020b0f0a31920e5b7e7e120d4560453b67b70733 (patch) | |
| tree | f86878d9930a3c58f62eda4008628fc2fa7dbcaa /include/scsi | |
| parent | ca44532139514f5fb0a5a081cd8576e4abe54e65 (diff) | |
| download | linux-020b0f0a31920e5b7e7e120d4560453b67b70733.tar.gz linux-020b0f0a31920e5b7e7e120d4560453b67b70733.tar.bz2 linux-020b0f0a31920e5b7e7e120d4560453b67b70733.zip | |
scsi: core: Replace sdev->device_busy with sbitmap
SCSI currently uses an atomic variable to track queue depth for each
attached device. The queue depth depends on many factors such as transport
type and device implementation. In addition, the SCSI device queue depth is
not a static entity but changes over time as a result of congestion
management.
While blk-mq currently tracks queue depth for each hctx, it can't easily be
changed to accommodate the SCSI per-device requirement.
The current approach of using an atomic variable doesn't scale well when
there are lots of CPU cores and the disk is very fast. IOPS can be
substantially impacted by the atomic in the hot path.
Replace the atomic variable sdev->device_busy with an sbitmap for tracking
the SCSI device queue depth.
It has been observed that IOPS is improved ~30% by this patchset in the
following test:
1) test machine(32 logical CPU cores)
Thread(s) per core: 2
Core(s) per socket: 8
Socket(s): 2
NUMA node(s): 2
Model name: Intel(R) Xeon(R) Silver 4110 CPU @ 2.10GHz
2) setup scsi_debug:
modprobe scsi_debug virtual_gb=128 max_luns=1 submit_queues=32 delay=0 max_queue=256
3) fio script:
fio --rw=randread --size=128G --direct=1 --ioengine=libaio --iodepth=2048 \
--numjobs=32 --bs=4k --group_reporting=1 --group_reporting=1 --runtime=60 \
--loops=10000 --name=job1 --filename=/dev/sdN
[mkp: fix device_busy reference in mpt3sas]
Link: https://lore.kernel.org/r/20210122023317.687987-14-ming.lei@redhat.com
Link: https://lore.kernel.org/linux-block/20200119071432.18558-6-ming.lei@redhat.com/
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'include/scsi')
| -rw-r--r-- | include/scsi/scsi_device.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index dd0b9f690a26..05c7c320ef32 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -8,6 +8,7 @@ #include <linux/blkdev.h> #include <scsi/scsi.h> #include <linux/atomic.h> +#include <linux/sbitmap.h> struct device; struct request_queue; @@ -106,7 +107,7 @@ struct scsi_device { struct list_head siblings; /* list of all devices on this host */ struct list_head same_target_siblings; /* just the devices sharing same target id */ - atomic_t device_busy; /* commands actually active on LLDD */ + struct sbitmap budget_map; atomic_t device_blocked; /* Device returned QUEUE_FULL. */ atomic_t restarts; @@ -592,7 +593,7 @@ static inline int scsi_device_supports_vpd(struct scsi_device *sdev) static inline int scsi_device_busy(struct scsi_device *sdev) { - return atomic_read(&sdev->device_busy); + return sbitmap_weight(&sdev->budget_map); } #define MODULE_ALIAS_SCSI_DEVICE(type) \ |