On Fri, Sep 06, 2019 at 10:24:20AM -0700, longli@xxxxxxxxxxxxxxxxx wrote:
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 advertises num_present_cpus() as number of hardware queues. This will have upper layer setup 1:1 mapping between hardware queue and CPU queue and avoid unnecessary locking when issuing I/O. Signed-off-by: Long Li <longli@xxxxxxxxxxxxx> --- Changes: v2: rely on default upper layer function to map queues. (suggested by Ming Lei <tom.leiming@xxxxxxxxx>) v3: use num_present_cpus() instead of num_online_cpus(). Hyper-v doesn't support hot-add CPUs. (suggested by Michael Kelley <mikelley@xxxxxxxxxxxxx>) v4: move change logs to after Signed-of-by drivers/scsi/storvsc_drv.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index b89269120a2d..cf987712041a 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -1836,8 +1836,7 @@ 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_present_cpus();
Just looking at the change notes for v3: why isn't this num_active_cpus() then? One can still isolate CPUs on hyper-v, no? -- Thanks, Sasha
