Re: [PATCH 02/11] hisi_sas: alloc queue id of slot according to device id

[Zhangfei Gao]

On Mon, Nov 7, 2016 at 8:48 PM, John Garry <john.garry@xxxxxxxxxx> wrote:
> From: Xiang Chen <chenxiang66@xxxxxxxxxxxxx>
>
> Currently slots are allocated from queues in a round-robin fashion.
> This causes a problem for internal commands in device mode. For this
> mode, we should ensure that the internal abort command is the last
> command seen in the host for that device. We can only ensure this when
> we place the internal abort command after the preceding commands for
> device that in the same queue, as there is no order in which the host
> will select a queue to execute the next command.

Is there performance penalty, since only one queue is supported for a device.

>
> This queue restriction makes supporting scsi mq more tricky in
> the future, but should not be a blocker.
>
> Note: Even though v1 hw does not support internal abort, the
>       allocation method is chosen to be the same for consistency.
>
> Signed-off-by: Xiang Chen <chenxiang66@xxxxxxxxxxxxx>
> Signed-off-by: John Garry <john.garry@xxxxxxxxxx>

Reviewed-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>