blk-mq : blk_mq_map_swqueue maybe

blk-mq : blk_mq_map_swqueue maybe

[nimisolo]

Hi Jens,

In blk_mq_map_swqueue(), all the blk_mq_hw_ctx's  nr_ctx  are set  
to zero, and then each blk_mq_ctx's  index_hw  is set to nr_ctx. 
I think the index_hw means the index of the hardware queue that map 
to this software queue, so maybe index_hw should be set to 
blk_mq_hw_ctx's queue_num.

I'm a student and I probably have misunderstood this code, please help
me to resolve this confusion. Thank you.

static void blk_mq_map_swqueue(struct request_queue *q)
{
        .........
        queue_for_each_hw_ctx(q, hctx, i) {
                .........
                hctx->nr_ctx = 0;
        }
        .........
        queue_for_each_ctx(q, ctx, i) {
                .........
                ctx->index_hw = hctx->nr_ctx;
                .........
        }
}

Re: blk-mq : blk_mq_map_swqueue maybe

[Chong Yuan]

nimisolo,

在 4/8/2015 10:10 AM, nimisolo 写道:
> Hi Jens,
>
> In blk_mq_map_swqueue(), all the blk_mq_hw_ctx's  nr_ctx  are set
> to zero, and then each blk_mq_ctx's  index_hw  is set to nr_ctx.
> I think the index_hw means the index of the hardware queue that map
> to this software queue, so maybe index_hw should be set to
> blk_mq_hw_ctx's queue_num.

Multiple sw queues may be dispatched to one hw queue.
So index_hw here means the index of the sw queue in corresponding hw queue.

--yc


>
> I'm a student and I probably have misunderstood this code, please help
> me to resolve this confusion. Thank you.
>
> static void blk_mq_map_swqueue(struct request_queue *q)
> {
>          .........
>          queue_for_each_hw_ctx(q, hctx, i) {
>                  .........
>                  hctx->nr_ctx = 0;
>          }
>          .........
>          queue_for_each_ctx(q, ctx, i) {
>                  .........
>                  ctx->index_hw = hctx->nr_ctx;
>                  .........
>          }
> }
> --
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