linux/include
Mike Christie e2f4ea4013 scsi: target: Allow userspace to request direct submissions
This allows userspace to request the fabric drivers do direct submissions
if they support it. With the new device file, submit_type, users can
write 0 - 2 to control how commands are submitted to the backend:

 0 - TARGET_FABRIC_DEFAULT_SUBMIT - LIO will use the fabric's default
     submission type. This is the default for compat.

 1 - TARGET_DIRECT_SUBMIT - LIO will submit the cmd to the backend from the
     calling context if the fabric the cmd was received on supports it,
     else it will use the fabric's default type.

 2 - TARGET_QUEUE_SUBMIT - LIO will queue the cmd to the LIO submission
     workqueue which will pass it to the backend.

When using an NVMe drive and vhost-scsi with direct submission we see
around a 20% improvement in 4K I/Os:

fio jobs        1       2       4       8       10
--------------------------------------------------
defer           94K     190K    394K    770K    890K
direct          128K    252K    488K    950K    -

And when using the queueing mode, we now no longer see issues like where
the iSCSI tx thread is blocked in the block layer waiting on a tag so it
can't respond to a nop or perform I/Os for other LUs.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Link: https://lore.kernel.org/r/20230928020907.5730-6-michael.christie@oracle.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2023-10-13 15:53:58 -04:00
..
acpi Merge branches 'acpi-scan', 'acpi-tad', 'acpi-extlog' and 'acpi-misc' 2023-08-25 20:49:52 +02:00
asm-generic ata changes for 6.6 2023-09-05 12:37:28 -07:00
clocksource
crypto This update includes the following changes: 2023-08-29 11:23:29 -07:00
drm drm for 6.6-rc1 2023-08-30 13:34:34 -07:00
dt-bindings IOMMU Updates for Linux v6.6 2023-09-01 16:54:25 -07:00
keys
kunit - An extensive rework of kexec and crash Kconfig from Eric DeVolder 2023-08-29 14:53:51 -07:00
kvm
linux six smb3 client fixes, one fix for nls Kconfig, one minor spnego registry update 2023-09-09 19:56:23 -07:00
math-emu
media media updates for v6.6-rc1 2023-09-01 12:21:32 -07:00
memory
misc
net Including fixes from netfilter and bpf. 2023-09-07 18:33:07 -07:00
pcmcia
ras
rdma
rv rv: Set variable 'da_mon_##name' to static 2023-09-01 21:00:00 -04:00
scsi SCSI misc on 20230909 2023-09-09 12:01:33 -07:00
soc IOMMU Updates for Linux v6.6 2023-09-01 16:54:25 -07:00
sound ASoC: Name iov_iter argument as iterator instead of buffer 2023-09-01 15:38:49 +02:00
target scsi: target: Allow userspace to request direct submissions 2023-10-13 15:53:58 -04:00
trace tracing: Replace strlcpy with strscpy in trace/events/task.h 2023-09-01 21:00:00 -04:00
uapi RISC-V Patches for the 6.6 Merge Window, Part 2 (try 2) 2023-09-09 14:25:11 -07:00
ufs Merge branch 'fixes' into misc 2023-09-02 08:25:19 +01:00
vdso
video
xen dma-maping updates for Linux 6.6 2023-08-29 20:32:10 -07:00