>>>Subject: Re: [PATCH] storvsc: setup 1:1 mapping between hardware queue >>>and CPU queue >>> >>>On Tue, Aug 20, 2019 at 3:36 AM <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 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; >>>> + } >>> >>>Block layer provides the helper of blk_mq_map_queues(), so suggest you >>>to use the default cpu mapping, instead of inventing a new one. Thanks for the pointer. I'm sending a v2. Long >>> >>>thanks, >>>Ming Lei