[PATCH v8 17/18] scsi: megaraid_sas: Added support for shared host tagset for cpuhotplug

John Garry
2020-08-19T15:27:26Z

From: Kashyap Desai <kashyap.desai@broadcom.com>

Fusion adapters can steer completions to individual queues, and
we now have support for shared host-wide tags.
So we can enable multiqueue support for fusion adapters.

Once driver enable shared host-wide tags, cpu hotplug feature is also
supported as it was enabled using below patchsets -
commit bf0beec0607d ("blk-mq: drain I/O when all CPUs in a hctx are
offline")

Currently driver has provision to disable host-wide tags using
"host_tagset_enable" module parameter.

Once we do not have any major performance regression using host-wide
tags, we will drop the hand-crafted interrupt affinity settings.

Performance is also meeting the expecatation - (used both none and
mq-deadline scheduler)
24 Drive SSD on Aero with/without this patch can get 3.1M IOPs
3 VDs consist of 8 SAS SSD on Aero with/without this patch can get 3.1M
IOPs.

Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: John Garry <john.garry@huawei.com>
---
drivers/scsi/megaraid/megaraid_sas_base.c | 39 +++++++++++++++++++++
drivers/scsi/megaraid/megaraid_sas_fusion.c | 29 ++++++++-------
2 files changed, 55 insertions(+), 13 deletions(-)

diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index 861f7140f52e..6960922d0d7f 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -37,6 +37,7 @@
#include <linux/poll.h>
#include <linux/vmalloc.h>
#include <linux/irq_poll.h>
+#include <linux/blk-mq-pci.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
@@ -113,6 +114,10 @@ unsigned int enable_sdev_max_qd;
module_param(enable_sdev_max_qd, int, 0444);
MODULE_PARM_DESC(enable_sdev_max_qd, "Enable sdev max qd as can_queue. Default: 0");

+int host_tagset_enable = 1;
+module_param(host_tagset_enable, int, 0444);
+MODULE_PARM_DESC(host_tagset_enable, "Shared host tagset enable/disable Default: enable(1)");
+
MODULE_LICENSE("GPL");
MODULE_VERSION(MEGASAS_VERSION);
MODULE_AUTHOR("megaraidlinux.pdl@broadcom.com");
@@ -3119,6 +3124,19 @@ megasas_bios_param(struct scsi_device *sdev, struct block_device *bdev,
return 0;
}

+static int megasas_map_queues(struct Scsi_Host *shost)
+{
+ struct megasas_instance *instance;
+
+ instance = (struct megasas_instance *)shost->hostdata;
+
+ if (shost->nr_hw_queues == 1)
+ return 0;
+
+ return blk_mq_pci_map_queues(&shost->tag_set.map[HCTX_TYPE_DEFAULT],
+ instance->pdev, instance->low_latency_index_start);
+}
+
static void megasas_aen_polling(struct work_struct *work);

/**
@@ -3427,6 +3445,7 @@ static struct scsi_host_template megasas_template = {
.eh_timed_out = megasas_reset_timer,
.shost_attrs = megaraid_host_attrs,
.bios_param = megasas_bios_param,
+ .map_queues = megasas_map_queues,
.change_queue_depth = scsi_change_queue_depth,
.max_segment_size = 0xffffffff,
};
@@ -6808,6 +6827,26 @@ static int megasas_io_attach(struct megasas_instance *instance)
host->max_lun = MEGASAS_MAX_LUN;
host->max_cmd_len = 16;

+ /* Use shared host tagset only for fusion adaptors
+ * if there are managed interrupts (smp affinity enabled case).
+ * Single msix_vectors in kdump, so shared host tag is also disabled.
+ */
+
+ host->host_tagset = 0;
+ host->nr_hw_queues = 1;
+
+ if ((instance->adapter_type != MFI_SERIES) &&
+ (instance->msix_vectors > instance->low_latency_index_start) &&
+ host_tagset_enable &&
+ instance->smp_affinity_enable) {
+ host->host_tagset = 1;
+ host->nr_hw_queues = instance->msix_vectors -
+ instance->low_latency_index_start;
+ }
+
+ dev_info(&instance->pdev->dev,
+ "Max firmware commands: %d shared with nr_hw_queues = %d\n",
+ instance->max_fw_cmds, host->nr_hw_queues);
/*
* Notify the mid-layer about the new controller
*/
diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
index 0824410f78f8..a4251121f173 100644
--- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
+++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
@@ -359,24 +359,29 @@ megasas_get_msix_index(struct megasas_instance *instance,
{
int sdev_busy;

- /* nr_hw_queue = 1 for MegaRAID */
- struct blk_mq_hw_ctx *hctx =
- scmd->device->request_queue->queue_hw_ctx[0];
-
- sdev_busy = atomic_read(&hctx->nr_active);
+ /* TBD - if sml remove device_busy in future, driver
+ * should track counter in internal structure.
+ */
+ sdev_busy = atomic_read(&scmd->device->device_busy);

if (instance->perf_mode == MR_BALANCED_PERF_MODE &&
- sdev_busy > (data_arms * MR_DEVICE_HIGH_IOPS_DEPTH))
+ sdev_busy > (data_arms * MR_DEVICE_HIGH_IOPS_DEPTH)) {
cmd->request_desc->SCSIIO.MSIxIndex =
mega_mod64((atomic64_add_return(1, &instance->high_iops_outstanding) /
MR_HIGH_IOPS_BATCH_COUNT), instance->low_latency_index_start);
- else if (instance->msix_load_balance)
+ } else if (instance->msix_load_balance) {
cmd->request_desc->SCSIIO.MSIxIndex =
(mega_mod64(atomic64_add_return(1, &instance->total_io_count),
instance->msix_vectors));
- else
+ } else if (instance->host->nr_hw_queues > 1) {
+ u32 tag = blk_mq_unique_tag(scmd->request);
+
+ cmd->request_desc->SCSIIO.MSIxIndex = blk_mq_unique_tag_to_hwq(tag) +
+ instance->low_latency_index_start;
+ } else {
cmd->request_desc->SCSIIO.MSIxIndex =
instance->reply_map[raw_smp_processor_id()];
+ }
}

/**
@@ -956,9 +961,6 @@ megasas_alloc_cmds_fusion(struct megasas_instance *instance)
if (megasas_alloc_cmdlist_fusion(instance))
goto fail_exit;

- dev_info(&instance->pdev->dev, "Configured max firmware commands: %d\n",
- instance->max_fw_cmds);
-
/* The first 256 bytes (SMID 0) is not used. Don't add to the cmd list */
io_req_base = fusion->io_request_frames + MEGA_MPI2_RAID_DEFAULT_IO_FRAME_SIZE;
io_req_base_phys = fusion->io_request_frames_phys + MEGA_MPI2_RAID_DEFAULT_IO_FRAME_SIZE;
@@ -1102,8 +1104,9 @@ megasas_ioc_init_fusion(struct megasas_instance *instance)
MR_HIGH_IOPS_QUEUE_COUNT) && cur_intr_coalescing)
instance->perf_mode = MR_BALANCED_PERF_MODE;

- dev_info(&instance->pdev->dev, "Performance mode :%s\n",
- MEGASAS_PERF_MODE_2STR(instance->perf_mode));
+ dev_info(&instance->pdev->dev, "Performance mode :%s (latency index = %d)\n",
+ MEGASAS_PERF_MODE_2STR(instance->perf_mode),
+ instance->low_latency_index_start);

instance->fw_sync_cache_support = (scratch_pad_1 &
MR_CAN_HANDLE_SYNC_CACHE_OFFSET) ? 1 : 0;
--
2.26.2