Re: [PATCH 21/22] atari_scsi: Allow can_queue to be increased for Falcon

From: Hannes Reinecke
Date: Mon Mar 14 2016 - 03:58:40 EST

On 03/14/2016 05:27 AM, Finn Thain wrote:
> The benefit of limiting can_queue to 1 is that atari_scsi shares the
> ST DMA chip more fairly with other drivers (e.g. falcon-ide).
> Unfortunately, this can limit SCSI bus utilization. On systems without
> IDE, atari_scsi should issue SCSI commands whenever it can arbitrate for
> the bus. Make that possible by making can_queue configurable.
> Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/scsi/atari_scsi.c | 83 ++++++++++++----------------------------------
> 1 file changed, 22 insertions(+), 61 deletions(-)
Hmm. We actually have a similar reasoning in the aic7xxx driver,
where the driver core wants to setup pointers to the _next_ command.
So maybe it makes sense to add a pointer to the 'next' command
somewhere in the NCR core structure, to be submitted whenever bus
arbitration tells you so?

But in the end it really looks like a real issue somewhere in the
code, be it the driver or the block/scsi layer.

Nevertheless, setting it to '1' is certainly the correct way here.

Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>


Dr. Hannes Reinecke Teamlead Storage & Networking
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