openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

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>
This commit is contained in:
John Garry 2020-07-09 20:23:20 +08:00 committed by Martin K. Petersen
parent c87bf24cfb
commit c10fa55f5e
1 changed files with 68 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

80
drivers/scsi/scsi_debug.c
View File

@ -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 @@ static int resp_rwp_zone(struct scsi_cmnd *scp, struct sdebug_dev_info *devip)
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;