From: Melanie Plageman (Microsoft) <melanieplageman@xxxxxxxxx> Sent: Wednesday, February 24, 2021 3:30 PM
>
> Add ability to set the number of hardware queues with new module parameter,
> storvsc_max_hw_queues. The default value remains the number of CPUs. This
> functionality is useful in some environments (e.g. Microsoft Azure) where
> decreasing the number of hardware queues has been shown to improve
> performance.
>
> Signed-off-by: Melanie Plageman (Microsoft) <melanieplageman@xxxxxxxxx>
> ---
> Updated since v3:
> - permissions in octal
> - param type changed to unsigned int
> - removed value checking from module init function
> - simplified value checking logic in probe function
>
> drivers/scsi/storvsc_drv.c | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
> index 6bc5453cea8a..dfe005c03734 100644
> --- a/drivers/scsi/storvsc_drv.c
> +++ b/drivers/scsi/storvsc_drv.c
> @@ -366,10 +366,14 @@ static u32 max_outstanding_req_per_channel;
> static int storvsc_change_queue_depth(struct scsi_device *sdev, int queue_depth);
>
> static int storvsc_vcpus_per_sub_channel = 4;
> +static unsigned int storvsc_max_hw_queues;
>
> module_param(storvsc_ringbuffer_size, int, S_IRUGO);
> MODULE_PARM_DESC(storvsc_ringbuffer_size, "Ring buffer size (bytes)");
>
> +module_param(storvsc_max_hw_queues, uint, 0644);
> +MODULE_PARM_DESC(storvsc_max_hw_queues, "Maximum number of hardware queues");
> +
> module_param(storvsc_vcpus_per_sub_channel, int, S_IRUGO);
> MODULE_PARM_DESC(storvsc_vcpus_per_sub_channel, "Ratio of VCPUs to
> subchannels");
>
> @@ -1907,6 +1911,7 @@ static int storvsc_probe(struct hv_device *device,
> {
> int ret;
> int num_cpus = num_online_cpus();
> + int num_present_cpus = num_present_cpus();
> struct Scsi_Host *host;
> struct hv_host_device *host_dev;
> bool dev_is_ide = ((dev_id->driver_data == IDE_GUID) ? true : false);
> @@ -2015,8 +2020,17 @@ static int storvsc_probe(struct hv_device *device,
> * For non-IDE disks, the host supports multiple channels.
> * Set the number of HW queues we are supporting.
> */
> - if (!dev_is_ide)
> - host->nr_hw_queues = num_present_cpus();
> + if (!dev_is_ide) {
> + if (storvsc_max_hw_queues > num_present_cpus) {
> + storvsc_max_hw_queues = 0;
> + storvsc_log(device, STORVSC_LOGGING_WARN,
> + "Resetting invalid storvsc_max_hw_queues value to default.\n");
> + }
> + if (storvsc_max_hw_queues)
> + host->nr_hw_queues = storvsc_max_hw_queues;
> + else
> + host->nr_hw_queues = num_present_cpus;
> + }
>
> /*
> * Set the error handler work queue.
> --
> 2.20.1
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
