Which core does a NVMe IO request would go?

[harryxiyou]

On Thu, Sep 11, 2014 at 3:46 AM, harryxiyou <harryxiyou at gmail.com> wrote:
> On Thu, Sep 11, 2014 at 3:43 AM, harryxiyou <harryxiyou at gmail.com> wrote:
>> Dear all,
>>
>> I am not sure "Which core does a NVMe IO request would go?" after
>> I read the NVMe driver source codes.
>>
>> The code says that,
>>
>>
>>  648 static int nvme_make_request(struct request_queue *q, struct request *req)
>>  649 {
>>  650     struct nvme_ns *ns = q->queuedata;
>>  651     struct nvme_queue *nvmeq = get_nvmeq(ns->dev);
>> ...
>>  659
>>  660     return result;
>>  661 }
>>
>>
>>  289 struct nvme_queue *get_nvmeq(struct nvme_dev *dev)
>>  290 {
>>  291     return dev->queues[get_cpu() + 1];
>>  292 }
>>
>>
>> dev->queues[get_cpu() + 1] tells us which core it goes but I don't know
>> what get_cpu() returns.
>>
>>
>> Could you please give me some suggestions?
>
> Maybe, I find the answers like this.
>
> get_cpu() disables kernel preemption prior to returning the current
> processor number
>

BTW, I cannot find the NVMe controller handle function

675 static int nvme_process_cq(struct nvme_queue *nvmeq)
 676 {
 677     u16 head, phase;
 678
 679     head = nvmeq->cq_head;
 680     phase = nvmeq->cq_phase;
 681
 682     for (;;) {
 683         void *ctx;
 684         nvme_completion_fn fn;
...
 693
 694         ctx = free_cmdid(nvmeq, cqe.command_id, &fn);
 695         fn(nvmeq, ctx, &cqe);
 696     }
}

I cannot find the fn function, could anyone give me some suggestions?

Thanks, Harry