From: Long Li Date: Tue, 14 Jan 2020 00:08:36 +0000 (-0800) Subject: scsi: storvsc: Correctly set number of hardware queues for IDE disk X-Git-Tag: v5.15~4698^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=7b571c19d4c0b78d27dd3bf1f3c42e4032390af6;p=platform%2Fkernel%2Flinux-starfive.git scsi: storvsc: Correctly set number of hardware queues for IDE disk Commit 0ed881027690 ("scsi: storvsc: setup 1:1 mapping between hardware queue and CPU queue") introduced a regression for disks attached to IDE. For these disks the host VSP only offers one VMBUS channel. Setting multiple queues can overload the VMBUS channel and result in performance drop for high queue depth workload on system with large number of CPUs. Fix it by leaving the number of hardware queues to 1 (default value) for IDE disks. Fixes: 0ed881027690 ("scsi: storvsc: setup 1:1 mapping between hardware queue and CPU queue") Link: https://lore.kernel.org/r/1578960516-108228-1-git-send-email-longli@linuxonhyperv.com Reviewed-by: Ming Lei Signed-off-by: Long Li Signed-off-by: Martin K. Petersen --- diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index f8faf8b..fb41636 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -1842,9 +1842,11 @@ static int storvsc_probe(struct hv_device *device, */ host->sg_tablesize = (stor_device->max_transfer_bytes >> PAGE_SHIFT); /* + * For non-IDE disks, the host supports multiple channels. * Set the number of HW queues we are supporting. */ - host->nr_hw_queues = num_present_cpus(); + if (!dev_is_ide) + host->nr_hw_queues = num_present_cpus(); /* * Set the error handler work queue.