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| author | Mike Christie <michael.christie@oracle.com> | 2021-02-27 11:00:06 -0600 |
|---|---|---|
| committer | Martin K. Petersen <martin.petersen@oracle.com> | 2021-03-04 17:37:03 -0500 |
| commit | 39ae3edda325e9cf9e978c9788affe88231f3b34 (patch) | |
| tree | ee148448ca96958fd380291d4871a8ad719ad9f0 /include/target | |
| parent | 3d75948b8320ac167ec2efe5a8ebf44bdcb3cc14 (diff) | |
| download | linux-next-39ae3edda325e9cf9e978c9788affe88231f3b34.tar.gz | |
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>
Diffstat (limited to 'include/target')
| -rw-r--r-- | include/target/target_core_base.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index cf445c3a551a..d1f7d2a45354 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -944,11 +944,20 @@ static inline struct se_portal_group *param_to_tpg(struct config_item *item) tpg_param_group); } +enum { + /* Use se_cmd's cpuid for completion */ + SE_COMPL_AFFINITY_CPUID = -1, + /* Complete on current CPU */ + SE_COMPL_AFFINITY_CURR_CPU = -2, +}; + struct se_wwn { struct target_fabric_configfs *wwn_tf; void *priv; struct config_group wwn_group; struct config_group fabric_stat_group; + struct config_group param_group; + int cmd_compl_affinity; }; static inline void atomic_inc_mb(atomic_t *v) |