Mike Christie 39ae3edda3 scsi: target: core: Make completion affinity configurable ... It may not always be best to complete the IO on same CPU as it was submitted on. This commit allows userspace to configure it. This has been useful for vhost-scsi where we have a single thread for submissions and completions. If we force the completion on the submission CPU we may be adding conflicts with what the user has setup in the lower levels with settings like the block layer rq_affinity or the driver's IRQ or softirq (the network's rps_cpus value) settings. We may also want to set it up where the vhost thread runs on CPU N and does its submissions/completions there, and then have LIO do its completion booking on CPU M, but can't configure the lower levels due to issues like using dm-multipath with lots of paths (the path selector can throw commands all over the system because it's only taking into account latency/throughput at its level). The new setting is in: /sys/kernel/config/target/$fabric/$target/param/cmd_completion_affinity Writing: -1 -> Gives the current default behavior of completing on the submission CPU. -2 -> Completes the cmd on the CPU the lower layers sent it to us from. > 0 -> Completes on the CPU userspace has specified. Link: https://lore.kernel.org/r/20210227170006.5077-26-michael.christie@oracle.com Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com> Signed-off-by: Mike Christie <michael.christie@oracle.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>		2021-03-04 17:37:03 -05:00
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iscsi	scsi: target: Make iscsit_register_transport() return void	2020-08-04 20:56:56 -04:00
target_core_backend.h	scsi: target: core: Fix backend plugging	2021-03-04 17:37:02 -05:00
target_core_base.h	scsi: target: core: Make completion affinity configurable	2021-03-04 17:37:03 -05:00
target_core_fabric.h	scsi: target: core: Add workqueue based cmd submission	2021-03-04 17:37:02 -05:00