| Message ID | 20211125151048.103910-4-hare@suse.de (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | scsi: enabled reserved commands for LLDDs | expand |
On 11/25/21 07:10, Hannes Reinecke wrote: > Quite some drivers are using management commands internally, which > typically use the same hardware tag pool (ie they are being allocated > from the same hardware resources) as the 'normal' I/O commands. > These commands are set aside before allocating the block-mq tag bitmap, > so they'll never show up as busy in the tag map. > The block-layer, OTOH, already has 'reserved_tags' to handle precisely > this situation. > So this patch adds a new field 'nr_reserved_cmds' to the SCSI host > template to instruct the block layer to set aside a tag space for these > management commands by using reserved tags. Reviewed-by: Bart Van Assche <bvanassche@acm.org>
On 11/25/2021 7:10 AM, Hannes Reinecke wrote: > Quite some drivers are using management commands internally, which > typically use the same hardware tag pool (ie they are being allocated > from the same hardware resources) as the 'normal' I/O commands. > These commands are set aside before allocating the block-mq tag bitmap, > so they'll never show up as busy in the tag map. > The block-layer, OTOH, already has 'reserved_tags' to handle precisely > this situation. > So this patch adds a new field 'nr_reserved_cmds' to the SCSI host > template to instruct the block layer to set aside a tag space for these > management commands by using reserved tags. > > Signed-off-by: Hannes Reinecke <hare@suse.de> > --- Reviewed-by: Asutosh Das <asutoshd@codeaurora.org> > drivers/scsi/hosts.c | 3 +++ > drivers/scsi/scsi_lib.c | 9 ++++++++- > include/scsi/scsi_host.h | 22 +++++++++++++++++++++- > 3 files changed, 32 insertions(+), 2 deletions(-) > > diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c > index a539fa2fb221..8ee7a7279b6b 100644 > --- a/drivers/scsi/hosts.c > +++ b/drivers/scsi/hosts.c > @@ -482,6 +482,9 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) > if (sht->virt_boundary_mask) > shost->virt_boundary_mask = sht->virt_boundary_mask; > > + if (sht->nr_reserved_cmds) > + shost->nr_reserved_cmds = sht->nr_reserved_cmds; > + > device_initialize(&shost->shost_gendev); > dev_set_name(&shost->shost_gendev, "host%d", shost->host_no); > shost->shost_gendev.bus = &scsi_bus_type; > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index 6fbd36c9c416..e8f1025d0ed8 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1939,7 +1939,9 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost) > tag_set->ops = &scsi_mq_ops_no_commit; > tag_set->nr_hw_queues = shost->nr_hw_queues ? : 1; > tag_set->nr_maps = shost->nr_maps ? : 1; > - tag_set->queue_depth = shost->can_queue; > + tag_set->queue_depth = > + shost->can_queue + shost->nr_reserved_cmds; > + tag_set->reserved_tags = shost->nr_reserved_cmds; > tag_set->cmd_size = cmd_size; > tag_set->numa_node = NUMA_NO_NODE; > tag_set->flags = BLK_MQ_F_SHOULD_MERGE; > @@ -1964,6 +1966,9 @@ void scsi_mq_destroy_tags(struct Scsi_Host *shost) > * @nowait: do not wait for command allocation to succeed. > * > * Allocates a SCSI command for internal LLDD use. > + * If 'nr_reserved_commands' is spectified by the host the > + * command will be allocated from the reserved tag pool; > + * otherwise the normal tag pool will be used. > */ > struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev, > int data_direction, bool nowait) > @@ -1973,6 +1978,8 @@ struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev, > blk_mq_req_flags_t flags = 0; > int op; > > + if (sdev->host->nr_reserved_cmds) > + flags |= BLK_MQ_REQ_RESERVED; > if (nowait) > flags |= BLK_MQ_REQ_NOWAIT; > op = (data_direction == DMA_TO_DEVICE) ? > diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h > index 6f49a8940dc4..7512d97aceb4 100644 > --- a/include/scsi/scsi_host.h > +++ b/include/scsi/scsi_host.h > @@ -367,10 +367,19 @@ struct scsi_host_template { > /* > * This determines if we will use a non-interrupt driven > * or an interrupt driven scheme. It is set to the maximum number > - * of simultaneous commands a single hw queue in HBA will accept. > + * of simultaneous commands a single hw queue in HBA will accept > + * excluding internal commands. > */ > int can_queue; > > + /* > + * This determines how many commands the HBA will set aside > + * for internal commands. This number will be added to > + * @can_queue to calcumate the maximum number of simultaneous > + * commands sent to the host. > + */ > + int nr_reserved_cmds; > + > /* > * In many instances, especially where disconnect / reconnect are > * supported, our host also has an ID on the SCSI bus. If this is > @@ -608,6 +617,11 @@ struct Scsi_Host { > unsigned short max_cmd_len; > > int this_id; > + > + /* > + * Number of commands this host can handle at the same time. > + * This excludes reserved commands as specified by nr_reserved_cmds. > + */ > int can_queue; > short cmd_per_lun; > short unsigned int sg_tablesize; > @@ -626,6 +640,12 @@ struct Scsi_Host { > */ > unsigned nr_hw_queues; > unsigned nr_maps; > + > + /* > + * Number of reserved commands to allocate, if any. > + */ > + unsigned nr_reserved_cmds; > + > unsigned active_mode:2; > > /* >
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c index a539fa2fb221..8ee7a7279b6b 100644 --- a/drivers/scsi/hosts.c +++ b/drivers/scsi/hosts.c @@ -482,6 +482,9 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize) if (sht->virt_boundary_mask) shost->virt_boundary_mask = sht->virt_boundary_mask; + if (sht->nr_reserved_cmds) + shost->nr_reserved_cmds = sht->nr_reserved_cmds; + device_initialize(&shost->shost_gendev); dev_set_name(&shost->shost_gendev, "host%d", shost->host_no); shost->shost_gendev.bus = &scsi_bus_type; diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 6fbd36c9c416..e8f1025d0ed8 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1939,7 +1939,9 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost) tag_set->ops = &scsi_mq_ops_no_commit; tag_set->nr_hw_queues = shost->nr_hw_queues ? : 1; tag_set->nr_maps = shost->nr_maps ? : 1; - tag_set->queue_depth = shost->can_queue; + tag_set->queue_depth = + shost->can_queue + shost->nr_reserved_cmds; + tag_set->reserved_tags = shost->nr_reserved_cmds; tag_set->cmd_size = cmd_size; tag_set->numa_node = NUMA_NO_NODE; tag_set->flags = BLK_MQ_F_SHOULD_MERGE; @@ -1964,6 +1966,9 @@ void scsi_mq_destroy_tags(struct Scsi_Host *shost) * @nowait: do not wait for command allocation to succeed. * * Allocates a SCSI command for internal LLDD use. + * If 'nr_reserved_commands' is spectified by the host the + * command will be allocated from the reserved tag pool; + * otherwise the normal tag pool will be used. */ struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev, int data_direction, bool nowait) @@ -1973,6 +1978,8 @@ struct scsi_cmnd *scsi_get_internal_cmd(struct scsi_device *sdev, blk_mq_req_flags_t flags = 0; int op; + if (sdev->host->nr_reserved_cmds) + flags |= BLK_MQ_REQ_RESERVED; if (nowait) flags |= BLK_MQ_REQ_NOWAIT; op = (data_direction == DMA_TO_DEVICE) ? diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index 6f49a8940dc4..7512d97aceb4 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -367,10 +367,19 @@ struct scsi_host_template { /* * This determines if we will use a non-interrupt driven * or an interrupt driven scheme. It is set to the maximum number - * of simultaneous commands a single hw queue in HBA will accept. + * of simultaneous commands a single hw queue in HBA will accept + * excluding internal commands. */ int can_queue; + /* + * This determines how many commands the HBA will set aside + * for internal commands. This number will be added to + * @can_queue to calcumate the maximum number of simultaneous + * commands sent to the host. + */ + int nr_reserved_cmds; + /* * In many instances, especially where disconnect / reconnect are * supported, our host also has an ID on the SCSI bus. If this is @@ -608,6 +617,11 @@ struct Scsi_Host { unsigned short max_cmd_len; int this_id; + + /* + * Number of commands this host can handle at the same time. + * This excludes reserved commands as specified by nr_reserved_cmds. + */ int can_queue; short cmd_per_lun; short unsigned int sg_tablesize; @@ -626,6 +640,12 @@ struct Scsi_Host { */ unsigned nr_hw_queues; unsigned nr_maps; + + /* + * Number of reserved commands to allocate, if any. + */ + unsigned nr_reserved_cmds; + unsigned active_mode:2; /*
Quite some drivers are using management commands internally, which typically use the same hardware tag pool (ie they are being allocated from the same hardware resources) as the 'normal' I/O commands. These commands are set aside before allocating the block-mq tag bitmap, so they'll never show up as busy in the tag map. The block-layer, OTOH, already has 'reserved_tags' to handle precisely this situation. So this patch adds a new field 'nr_reserved_cmds' to the SCSI host template to instruct the block layer to set aside a tag space for these management commands by using reserved tags. Signed-off-by: Hannes Reinecke <hare@suse.de> --- drivers/scsi/hosts.c | 3 +++ drivers/scsi/scsi_lib.c | 9 ++++++++- include/scsi/scsi_host.h | 22 +++++++++++++++++++++- 3 files changed, 32 insertions(+), 2 deletions(-)