Re: [PATCH 7/9] scsi: hisi_sas_v3: convert private reply queue to blk-mq hw queue

[Hannes Reinecke <hare@suse.de>]

On 5/31/19 8:34 AM, Ming Lei wrote:
> On Fri, May 31, 2019 at 2:21 PM Hannes Reinecke <hare@suse.de> wrote:
>>
>> On 5/31/19 4:27 AM, Ming Lei wrote:
>>> SCSI's reply qeueue is very similar with blk-mq's hw queue, both
>>> assigned by IRQ vector, so map te private reply queue into blk-mq's hw
>>> queue via .host_tagset.
>>>
>>> Then the private reply mapping can be removed.
>>>
>>> Another benefit is that the request/irq lost issue may be solved in
>>> generic approach because managed IRQ may be shutdown during CPU
>>> hotplug.
>>>
>>> Signed-off-by: Ming Lei <ming.lei@redhat.com>
>>> ---
>>>  drivers/scsi/hisi_sas/hisi_sas.h       |  2 +-
>>>  drivers/scsi/hisi_sas/hisi_sas_main.c  | 36 ++++++++++----------
>>>  drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 46 +++++++++-----------------
>>>  3 files changed, 36 insertions(+), 48 deletions(-)
>>>
>>> diff --git a/drivers/scsi/hisi_sas/hisi_sas.h b/drivers/scsi/hisi_sas/hisi_sas.h
>>> index fc87994b5d73..3d48848dbde7 100644
>>> --- a/drivers/scsi/hisi_sas/hisi_sas.h
>>> +++ b/drivers/scsi/hisi_sas/hisi_sas.h
>>> @@ -26,6 +26,7 @@
>>>  #include <linux/platform_device.h>
>>>  #include <linux/property.h>
>>>  #include <linux/regmap.h>
>>> +#include <linux/blk-mq-pci.h>
>>>  #include <scsi/sas_ata.h>
>>>  #include <scsi/libsas.h>
>>>
>>> @@ -378,7 +379,6 @@ struct hisi_hba {
>>>       u32 intr_coal_count;    /* Interrupt count to coalesce */
>>>
>>>       int cq_nvecs;
>>> -     unsigned int *reply_map;
>>>
>>>       /* debugfs memories */
>>>       u32 *debugfs_global_reg;
>>> diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c
>>> index 8a7feb8ed8d6..a1c1f30b9fdb 100644
>>> --- a/drivers/scsi/hisi_sas/hisi_sas_main.c
>>> +++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
>>> @@ -441,6 +441,19 @@ static int hisi_sas_dif_dma_map(struct hisi_hba *hisi_hba,
>>>       return rc;
>>>  }
>>>
>>> +static struct scsi_cmnd *sas_task_to_scsi_cmd(struct sas_task *task)
>>> +{
>>> +     if (!task->uldd_task)
>>> +             return NULL;
>>> +
>>> +     if (dev_is_sata(task->dev)) {
>>> +             struct ata_queued_cmd *qc = task->uldd_task;
>>> +             return qc->scsicmd;
>>> +     } else {
>>> +             return task->uldd_task;
>>> +     }
>>> +}
>>> +
>>>  static int hisi_sas_task_prep(struct sas_task *task,
>>>                             struct hisi_sas_dq **dq_pointer,
>>>                             bool is_tmf, struct hisi_sas_tmf_task *tmf,
>>> @@ -459,6 +472,7 @@ static int hisi_sas_task_prep(struct sas_task *task,
>>>       struct hisi_sas_dq *dq;
>>>       unsigned long flags;
>>>       int wr_q_index;
>>> +     struct scsi_cmnd *scsi_cmnd;
>>>
>>>       if (DEV_IS_GONE(sas_dev)) {
>>>               if (sas_dev)
>>> @@ -471,9 +485,10 @@ static int hisi_sas_task_prep(struct sas_task *task,
>>>               return -ECOMM;
>>>       }
>>>
>>> -     if (hisi_hba->reply_map) {
>>> -             int cpu = raw_smp_processor_id();
>>> -             unsigned int dq_index = hisi_hba->reply_map[cpu];
>>> +     scsi_cmnd = sas_task_to_scsi_cmd(task);
>>> +     if (hisi_hba->shost->hostt->host_tagset) {
>>> +             unsigned int dq_index = scsi_cmnd_hctx_index(
>>> +                             hisi_hba->shost, scsi_cmnd);
>>>
>>>               *dq_pointer = dq = &hisi_hba->dq[dq_index];
>>>       } else {
>>> @@ -503,21 +518,8 @@ static int hisi_sas_task_prep(struct sas_task *task,
>>>
>>>       if (hisi_hba->hw->slot_index_alloc)
>>>               rc = hisi_hba->hw->slot_index_alloc(hisi_hba, device);
>>> -     else {
>>> -             struct scsi_cmnd *scsi_cmnd = NULL;
>>> -
>>> -             if (task->uldd_task) {
>>> -                     struct ata_queued_cmd *qc;
>>> -
>>> -                     if (dev_is_sata(device)) {
>>> -                             qc = task->uldd_task;
>>> -                             scsi_cmnd = qc->scsicmd;
>>> -                     } else {
>>> -                             scsi_cmnd = task->uldd_task;
>>> -                     }
>>> -             }
>>> +     else
>>>               rc  = hisi_sas_slot_index_alloc(hisi_hba, scsi_cmnd);
>>> -     }
>>>       if (rc < 0)
>>>               goto err_out_dif_dma_unmap;
>>>
>>> diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
>>> index 49620c2411df..063e50e5b30c 100644
>>> --- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
>>> +++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
>>> @@ -2344,30 +2344,6 @@ static irqreturn_t cq_interrupt_v3_hw(int irq_no, void *p)
>>>       return IRQ_HANDLED;
>>>  }
>>>
>>> -static void setup_reply_map_v3_hw(struct hisi_hba *hisi_hba, int nvecs)
>>> -{
>>> -     const struct cpumask *mask;
>>> -     int queue, cpu;
>>> -
>>> -     for (queue = 0; queue < nvecs; queue++) {
>>> -             struct hisi_sas_cq *cq = &hisi_hba->cq[queue];
>>> -
>>> -             mask = pci_irq_get_affinity(hisi_hba->pci_dev, queue +
>>> -                                         BASE_VECTORS_V3_HW);
>>> -             if (!mask)
>>> -                     goto fallback;
>>> -             cq->pci_irq_mask = mask;
>>> -             for_each_cpu(cpu, mask)
>>> -                     hisi_hba->reply_map[cpu] = queue;
>>> -     }
>>> -     return;
>>> -
>>> -fallback:
>>> -     for_each_possible_cpu(cpu)
>>> -             hisi_hba->reply_map[cpu] = cpu % hisi_hba->queue_count;
>>> -     /* Don't clean all CQ masks */
>>> -}
>>> -
>>>  static int interrupt_init_v3_hw(struct hisi_hba *hisi_hba)
>>>  {
>>>       struct device *dev = hisi_hba->dev;
>>> @@ -2383,11 +2359,6 @@ static int interrupt_init_v3_hw(struct hisi_hba *hisi_hba)
>>>
>>>               min_msi = MIN_AFFINE_VECTORS_V3_HW;
>>>
>>> -             hisi_hba->reply_map = devm_kcalloc(dev, nr_cpu_ids,
>>> -                                                sizeof(unsigned int),
>>> -                                                GFP_KERNEL);
>>> -             if (!hisi_hba->reply_map)
>>> -                     return -ENOMEM;
>>>               vectors = pci_alloc_irq_vectors_affinity(hisi_hba->pci_dev,
>>>                                                        min_msi, max_msi,
>>>                                                        PCI_IRQ_MSI |
>>> @@ -2395,7 +2366,6 @@ static int interrupt_init_v3_hw(struct hisi_hba *hisi_hba)
>>>                                                        &desc);
>>>               if (vectors < 0)
>>>                       return -ENOENT;
>>> -             setup_reply_map_v3_hw(hisi_hba, vectors - BASE_VECTORS_V3_HW);
>>>       } else {
>>>               min_msi = max_msi;
>>>               vectors = pci_alloc_irq_vectors(hisi_hba->pci_dev, min_msi,
>>> @@ -2896,6 +2866,18 @@ static void debugfs_snapshot_restore_v3_hw(struct hisi_hba *hisi_hba)
>>>       clear_bit(HISI_SAS_REJECT_CMD_BIT, &hisi_hba->flags);
>>>  }
>>>
>>> +static int hisi_sas_map_queues(struct Scsi_Host *shost)
>>> +{
>>> +     struct hisi_hba *hisi_hba = shost_priv(shost);
>>> +     struct blk_mq_queue_map *qmap = &shost->tag_set.map[HCTX_TYPE_DEFAULT];
>>> +
>>> +     if (auto_affine_msi_experimental)
>>> +             return blk_mq_pci_map_queues(qmap, hisi_hba->pci_dev,
>>> +                             BASE_VECTORS_V3_HW);
>>> +     else
>>> +             return blk_mq_map_queues(qmap);
>>> +}
>>> +
>>>  static struct scsi_host_template sht_v3_hw = {
>>>       .name                   = DRV_NAME,
>>>       .module                 = THIS_MODULE,
>>
>> As mentioned, we should be using a common function here.
>>
>>> @@ -2906,6 +2888,8 @@ static struct scsi_host_template sht_v3_hw = {
>>>       .scan_start             = hisi_sas_scan_start,
>>>       .change_queue_depth     = sas_change_queue_depth,
>>>       .bios_param             = sas_bios_param,
>>> +     .map_queues             = hisi_sas_map_queues,
>>> +     .host_tagset            = 1,
>>>       .this_id                = -1,
>>>       .sg_tablesize           = HISI_SAS_SGE_PAGE_CNT,
>>>       .sg_prot_tablesize      = HISI_SAS_SGE_PAGE_CNT,
>>> @@ -3092,6 +3076,8 @@ hisi_sas_v3_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>>>       if (hisi_sas_debugfs_enable)
>>>               hisi_sas_debugfs_init(hisi_hba);
>>>
>>> +     shost->nr_hw_queues = hisi_hba->cq_nvecs;
>>> +
>>>       rc = scsi_add_host(shost, dev);
>>>       if (rc)
>>>               goto err_out_ha;
>>>
>> Well, I'd rather see the v3 hardware converted to 'real' blk-mq first;
>> the hardware itself is pretty much multiqueue already, so we should be
>> better off converting it to blk-mq.
> 
> From John Garry's input, the tags is still hostwide, then not sure how to
> partition the hostwide tags into each hw queue's tags. That can be quite
> hard to do if the queue depth isn't big enough.
> 
Shouldn't be much of an issue; the conversion to blk-mq would still be
using a host-wide tag map.
Problem is more the 'v2' hardware, which has some pretty dodgy hardware
limitations. But I'll be looking into it and will be posting a patch.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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