| Message ID | 1666693096-180008-4-git-send-email-john.garry@huawei.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | blk-mq/libata/scsi: SCSI driver tagging improvements Part I | expand |
On 10/25/22 19:17, John Garry wrote: > From: Hannes Reinecke <hare@suse.de> > > 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> > #jpg: Set tag_set->queue_depth = shost->can_queue, and not > = shost->can_queue + shost->nr_reserved_cmds; > Signed-off-by: John Garry <john.garry@huawei.com> > --- > drivers/scsi/hosts.c | 3 +++ > drivers/scsi/scsi_lib.c | 2 ++ > include/scsi/scsi_host.h | 15 ++++++++++++++- > 3 files changed, 19 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c > index 12346e2297fd..db89afc37bc9 100644 > --- a/drivers/scsi/hosts.c > +++ b/drivers/scsi/hosts.c > @@ -489,6 +489,9 @@ 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; > + Nit: the if is not really necessary I think. But it does not hurt. > 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 39d4fd124375..a8c4e7c037ae 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1978,6 +1978,8 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost) > 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->reserved_tags = shost->nr_reserved_cmds; > + Why the blank line ? > tag_set->cmd_size = cmd_size; > tag_set->numa_node = dev_to_node(shost->dma_dev); > tag_set->flags = BLK_MQ_F_SHOULD_MERGE; > diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h > index 750ccf126377..91678c77398e 100644 > --- a/include/scsi/scsi_host.h > +++ b/include/scsi/scsi_host.h > @@ -360,10 +360,17 @@ 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 > + * including reserved commands. > */ > int can_queue; > > + /* > + * This determines how many commands the HBA will set aside > + * for reserved commands. > + */ > + 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 > @@ -611,6 +618,12 @@ struct Scsi_Host { > */ > unsigned nr_hw_queues; > unsigned nr_maps; > + > + /* > + * Number of reserved commands to allocate, if any. > + */ > + unsigned int nr_reserved_cmds; > + > unsigned active_mode:2; > > /*
On 10/27/22 03:18, Damien Le Moal wrote: > On 10/25/22 19:17, John Garry wrote: >> From: Hannes Reinecke <hare@suse.de> >> >> 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> >> #jpg: Set tag_set->queue_depth = shost->can_queue, and not >> = shost->can_queue + shost->nr_reserved_cmds; >> Signed-off-by: John Garry <john.garry@huawei.com> >> --- >> drivers/scsi/hosts.c | 3 +++ >> drivers/scsi/scsi_lib.c | 2 ++ >> include/scsi/scsi_host.h | 15 ++++++++++++++- >> 3 files changed, 19 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c >> index 12346e2297fd..db89afc37bc9 100644 >> --- a/drivers/scsi/hosts.c >> +++ b/drivers/scsi/hosts.c >> @@ -489,6 +489,9 @@ 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; >> + > > Nit: the if is not really necessary I think. But it does not hurt. > Yes, we do. Not all HBAs are able to figure out the number of reserved commands upfront; some modify that based on the PCI device used etc. So I'd keep it for now. Cheers, Hannes
On 27/10/2022 08:51, Hannes Reinecke wrote: >>> >>> Signed-off-by: Hannes Reinecke <hare@suse.de> >>> #jpg: Set tag_set->queue_depth = shost->can_queue, and not >>> = shost->can_queue + shost->nr_reserved_cmds; >>> Signed-off-by: John Garry <john.garry@huawei.com> >>> --- >>> drivers/scsi/hosts.c | 3 +++ >>> drivers/scsi/scsi_lib.c | 2 ++ >>> include/scsi/scsi_host.h | 15 ++++++++++++++- >>> 3 files changed, 19 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c >>> index 12346e2297fd..db89afc37bc9 100644 >>> --- a/drivers/scsi/hosts.c >>> +++ b/drivers/scsi/hosts.c >>> @@ -489,6 +489,9 @@ 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; >>> + >> >> Nit: the if is not really necessary I think. But it does not hurt. >> > Yes, we do. > Not all HBAs are able to figure out the number of reserved commands > upfront; some modify that based on the PCI device used etc. > So I'd keep it for now. I think logically Damien is right as in the shost alloc shost->nr_reserved_cmds is initially zero, so: if (sht->nr_reserved_cmds) shost->nr_reserved_cmds = sht->nr_reserved_cmds; is same as simply: shost->nr_reserved_cmds = sht->nr_reserved_cmds; However I am just copying the coding style. Thanks, John
> >> 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 39d4fd124375..a8c4e7c037ae 100644 >> --- a/drivers/scsi/scsi_lib.c >> +++ b/drivers/scsi/scsi_lib.c >> @@ -1978,6 +1978,8 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost) >> 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->reserved_tags = shost->nr_reserved_cmds; >> + > Why the blank line ? > I don't think that it is required, I can remedy. >> tag_set->cmd_size = cmd_size; Thanks, John
diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c index 12346e2297fd..db89afc37bc9 100644 --- a/drivers/scsi/hosts.c +++ b/drivers/scsi/hosts.c @@ -489,6 +489,9 @@ 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 39d4fd124375..a8c4e7c037ae 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1978,6 +1978,8 @@ int scsi_mq_setup_tags(struct Scsi_Host *shost) 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->reserved_tags = shost->nr_reserved_cmds; + tag_set->cmd_size = cmd_size; tag_set->numa_node = dev_to_node(shost->dma_dev); tag_set->flags = BLK_MQ_F_SHOULD_MERGE; diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h index 750ccf126377..91678c77398e 100644 --- a/include/scsi/scsi_host.h +++ b/include/scsi/scsi_host.h @@ -360,10 +360,17 @@ 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 + * including reserved commands. */ int can_queue; + /* + * This determines how many commands the HBA will set aside + * for reserved commands. + */ + 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 @@ -611,6 +618,12 @@ struct Scsi_Host { */ unsigned nr_hw_queues; unsigned nr_maps; + + /* + * Number of reserved commands to allocate, if any. + */ + unsigned int nr_reserved_cmds; + unsigned active_mode:2; /*