diff options
author | John Garry <john.garry@huawei.com> | 2020-07-09 15:23:20 +0300 |
---|---|---|
committer | Martin K. Petersen <martin.petersen@oracle.com> | 2020-07-14 06:42:48 +0300 |
commit | c10fa55f5e7ad3638237dd66fcb28a7225acdff8 (patch) | |
tree | 805dcbed5c8492a10862e0baf63f453fe6a65095 /drivers/scsi/scsi_debug.c | |
parent | c87bf24cfb60bce27b4d2c7e56ebfd86fb9d16bb (diff) |
scsi: scsi_debug: Support hostwide tags
Many SCSI HBAs support a hostwide tagset, whereby each command submitted to
the HW from all submission queues must have a unique tag identifier.
Normally this unique tag will be in the range [0, max queue], where "max
queue" is the depth of each of the submission queues.
Add support for this hostwide tag feature, via module parameter
"host_max_queue". A non-zero value means that the feature is enabled. In
this case, the submission queues are not exposed to upper layer, i.e. from
blk-mq prespective, the device has a single hw queue. There are 2 reasons
for this:
a. It is assumed that the host can support nr_hw_queues * can_queue
commands, but this is not true for hostwide tags
b. For nr_hw_queues != 0, the request tag is not unique over all HW
queues, and some HBA drivers want to use this tag for the hostwide tag
However, like many SCSI HBA drivers today - megaraid sas being an example -
the full set of HW submission queues are still used in the LLDD driver. So
instead of using a complicated "reply_map" to create a per-CPU submission
queue mapping like megaraid_sas (as it depends on a PCI device + MSIs) -
use a simple algorithm:
hwq = cpu % queue count
If the host_max_queue param is set non-zero, then the max queue depth is
fixed at this value also.
If and when hostwide shared tags are supported in blk-mq/scsi mid-layer,
then the policy to set nr_hw_queues = 0 for hostwide tags can be revised.
Link: https://lore.kernel.org/r/1594297400-24756-3-git-send-email-john.garry@huawei.com
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Diffstat (limited to 'drivers/scsi/scsi_debug.c')
-rw-r--r-- | drivers/scsi/scsi_debug.c | 80 |
1 files changed, 68 insertions, 12 deletions
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c index dc8fd6400e40..802ccd32d010 100644 --- a/drivers/scsi/scsi_debug.c +++ b/drivers/scsi/scsi_debug.c @@ -344,6 +344,7 @@ struct sdebug_defer { struct execute_work ew; int sqa_idx; /* index of sdebug_queue array */ int qc_idx; /* index of sdebug_queued_cmd array within sqa_idx */ + int hc_idx; /* hostwide tag index */ int issuing_cpu; bool init_hrt; bool init_wq; @@ -759,6 +760,7 @@ static int sdebug_dsense = DEF_D_SENSE; static int sdebug_every_nth = DEF_EVERY_NTH; static int sdebug_fake_rw = DEF_FAKE_RW; static unsigned int sdebug_guard = DEF_GUARD; +static int sdebug_host_max_queue; /* per host */ static int sdebug_lowest_aligned = DEF_LOWEST_ALIGNED; static int sdebug_max_luns = DEF_MAX_LUNS; static int sdebug_max_queue = SDEBUG_CANQUEUE; /* per submit queue */ @@ -4707,15 +4709,28 @@ fini: static struct sdebug_queue *get_queue(struct scsi_cmnd *cmnd) { - u32 tag = blk_mq_unique_tag(cmnd->request); - u16 hwq = blk_mq_unique_tag_to_hwq(tag); + u16 hwq; - pr_debug("tag=%#x, hwq=%d\n", tag, hwq); - if (WARN_ON_ONCE(hwq >= submit_queues)) - hwq = 0; + if (sdebug_host_max_queue) { + /* Provide a simple method to choose the hwq */ + hwq = smp_processor_id() % submit_queues; + } else { + u32 tag = blk_mq_unique_tag(cmnd->request); + + hwq = blk_mq_unique_tag_to_hwq(tag); + + pr_debug("tag=%#x, hwq=%d\n", tag, hwq); + if (WARN_ON_ONCE(hwq >= submit_queues)) + hwq = 0; + } return sdebug_q_arr + hwq; } +static u32 get_tag(struct scsi_cmnd *cmnd) +{ + return blk_mq_unique_tag(cmnd->request); +} + /* Queued (deferred) command completions converge here. */ static void sdebug_q_cmd_complete(struct sdebug_defer *sd_dp) { @@ -4747,8 +4762,8 @@ static void sdebug_q_cmd_complete(struct sdebug_defer *sd_dp) scp = sqcp->a_cmnd; if (unlikely(scp == NULL)) { spin_unlock_irqrestore(&sqp->qc_lock, iflags); - pr_err("scp is NULL, sqa_idx=%d, qc_idx=%d\n", - sd_dp->sqa_idx, qc_idx); + pr_err("scp is NULL, sqa_idx=%d, qc_idx=%d, hc_idx=%d\n", + sd_dp->sqa_idx, qc_idx, sd_dp->hc_idx); return; } devip = (struct sdebug_dev_info *)scp->device->hostdata; @@ -5451,6 +5466,10 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip, new_sd_dp = false; } + /* Set the hostwide tag */ + if (sdebug_host_max_queue) + sd_dp->hc_idx = get_tag(cmnd); + if (ndelay > 0 && ndelay < INCLUSIVE_TIMING_MAX_NS) ns_from_boot = ktime_get_boottime_ns(); @@ -5572,6 +5591,7 @@ module_param_named(every_nth, sdebug_every_nth, int, S_IRUGO | S_IWUSR); module_param_named(fake_rw, sdebug_fake_rw, int, S_IRUGO | S_IWUSR); module_param_named(guard, sdebug_guard, uint, S_IRUGO); module_param_named(host_lock, sdebug_host_lock, bool, S_IRUGO | S_IWUSR); +module_param_named(host_max_queue, sdebug_host_max_queue, int, S_IRUGO); module_param_string(inq_product, sdebug_inq_product_id, sizeof(sdebug_inq_product_id), S_IRUGO | S_IWUSR); module_param_string(inq_rev, sdebug_inq_product_rev, @@ -5642,6 +5662,8 @@ MODULE_PARM_DESC(every_nth, "timeout every nth command(def=0)"); MODULE_PARM_DESC(fake_rw, "fake reads/writes instead of copying (def=0)"); MODULE_PARM_DESC(guard, "protection checksum: 0=crc, 1=ip (def=0)"); MODULE_PARM_DESC(host_lock, "host_lock is ignored (def=0)"); +MODULE_PARM_DESC(host_max_queue, + "host max # of queued cmds (0 to max(def) [max_queue fixed equal for !0])"); MODULE_PARM_DESC(inq_product, "SCSI INQUIRY product string (def=\"scsi_debug\")"); MODULE_PARM_DESC(inq_rev, "SCSI INQUIRY revision string (def=\"" SDEBUG_VERSION "\")"); @@ -6141,7 +6163,8 @@ static ssize_t max_queue_store(struct device_driver *ddp, const char *buf, struct sdebug_queue *sqp; if ((count > 0) && (1 == sscanf(buf, "%d", &n)) && (n > 0) && - (n <= SDEBUG_CANQUEUE)) { + (n <= SDEBUG_CANQUEUE) && + (sdebug_host_max_queue == 0)) { block_unblock_all_queues(true); k = 0; for (j = 0, sqp = sdebug_q_arr; j < submit_queues; @@ -6164,6 +6187,17 @@ static ssize_t max_queue_store(struct device_driver *ddp, const char *buf, } static DRIVER_ATTR_RW(max_queue); +static ssize_t host_max_queue_show(struct device_driver *ddp, char *buf) +{ + return scnprintf(buf, PAGE_SIZE, "%d\n", sdebug_host_max_queue); +} + +/* + * Since this is used for .can_queue, and we get the hc_idx tag from the bitmap + * in range [0, sdebug_host_max_queue), we can't change it. + */ +static DRIVER_ATTR_RO(host_max_queue); + static ssize_t no_uld_show(struct device_driver *ddp, char *buf) { return scnprintf(buf, PAGE_SIZE, "%d\n", sdebug_no_uld); @@ -6503,6 +6537,7 @@ static struct attribute *sdebug_drv_attrs[] = { &driver_attr_ptype.attr, &driver_attr_dsense.attr, &driver_attr_fake_rw.attr, + &driver_attr_host_max_queue.attr, &driver_attr_no_lun_0.attr, &driver_attr_num_tgts.attr, &driver_attr_dev_size_mb.attr, @@ -6619,6 +6654,20 @@ static int __init scsi_debug_init(void) return -EINVAL; } + if ((sdebug_host_max_queue > SDEBUG_CANQUEUE) || + (sdebug_host_max_queue < 0)) { + pr_err("host_max_queue must be in range [0 %d]\n", + SDEBUG_CANQUEUE); + return -EINVAL; + } + + if (sdebug_host_max_queue && + (sdebug_max_queue != sdebug_host_max_queue)) { + sdebug_max_queue = sdebug_host_max_queue; + pr_warn("fixing max submit queue depth to host max queue depth, %d\n", + sdebug_max_queue); + } + sdebug_q_arr = kcalloc(submit_queues, sizeof(struct sdebug_queue), GFP_KERNEL); if (sdebug_q_arr == NULL) @@ -7257,7 +7306,10 @@ static int sdebug_driver_probe(struct device *dev) sdbg_host = to_sdebug_host(dev); - sdebug_driver_template.can_queue = sdebug_max_queue; + if (sdebug_host_max_queue) + sdebug_driver_template.can_queue = sdebug_host_max_queue; + else + sdebug_driver_template.can_queue = sdebug_max_queue; if (!sdebug_clustering) sdebug_driver_template.dma_boundary = PAGE_SIZE - 1; @@ -7272,9 +7324,13 @@ static int sdebug_driver_probe(struct device *dev) my_name, submit_queues, nr_cpu_ids); submit_queues = nr_cpu_ids; } - /* Decide whether to tell scsi subsystem that we want mq */ - /* Following should give the same answer for each host */ - hpnt->nr_hw_queues = submit_queues; + /* + * Decide whether to tell scsi subsystem that we want mq. The + * following should give the same answer for each host. If the host + * has a limit of hostwide max commands, then do not set. + */ + if (!sdebug_host_max_queue) + hpnt->nr_hw_queues = submit_queues; sdbg_host->shost = hpnt; *((struct sdebug_host_info **)hpnt->hostdata) = sdbg_host; |