From: Long Li <longli@xxxxxxxxxxxxx>
storvsc doesn't use a dedicated hardware queue for a given CPU queue. When
issuing I/O, it selects returning CPU (hardware queue) dynamically based on
vmbus channel usage across all channels.
This patch sets up a 1:1 mapping between hardware queue and CPU queue, thus
avoiding unnecessary locking at upper layer when issuing I/O.
Signed-off-by: Long Li <longli@xxxxxxxxxxxxx>
---
drivers/scsi/storvsc_drv.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index b89269120a2d..26c16d40ec46 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1682,6 +1682,18 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
return 0;
}
+static int storvsc_map_queues(struct Scsi_Host *shost)
+{
+ unsigned int cpu;
+ struct blk_mq_queue_map *qmap = &shost->tag_set.map[HCTX_TYPE_DEFAULT];
+
+ for_each_possible_cpu(cpu) {
+ qmap->mq_map[cpu] = cpu;
+ }
+
+ return 0;
+}
+
static struct scsi_host_template scsi_driver = {
.module = THIS_MODULE,
.name = "storvsc_host_t",
@@ -1697,6 +1709,7 @@ static struct scsi_host_template scsi_driver = {
.this_id = -1,
/* Make sure we dont get a sg segment crosses a page boundary */
.dma_boundary = PAGE_SIZE-1,
+ .map_queues = storvsc_map_queues,
.no_write_same = 1,
.track_queue_depth = 1,
};
@@ -1836,8 +1849,7 @@ static int storvsc_probe(struct hv_device *device,
/*
* Set the number of HW queues we are supporting.
*/
- if (stor_device->num_sc != 0)
- host->nr_hw_queues = stor_device->num_sc + 1;
+ host->nr_hw_queues = num_possible_cpus();
/*
* Set the error handler work queue.
--
2.17.1
