Re: [PATCH 0/3] mmc: Improve block layer requeueing behavior

[Adrian Hunter]

On 26/10/22 10:30, Christian Löhle wrote:
> Mmcblk relies on block layer requeueing to fulfill some requests under
> certain conditions. Improve the handling to get nicely ordered requests.
> 
> Using the terms a bit loosely to get a point across:
> Current behavior for 512 blksz and max_blk_count = 1 the scenario would
> be as follows:
> 
> - request for page 0 lba 0 to 7
> - request for page 1 lba 8 to 15
> - request for page 2 lba 16 to 23
> - request for page 3 lba 24 to 31
> 
> mmcblk modifies data->blocks = 1 for each and requeues,
> this leads to:
> 
> Access lba 0
> Access lba 8
> Access lba 16
> Access lba 24
> Access lba 1 (1. Requeue for page 0)
> Access lba 9 (1. Requeue for page 1)
> Access lba 17 (1. Requeue for page 2)
> Access lba 25 (1. Requeue for page 3)
> Access lba 2 (2. Requeue for page 0)
> ...
> 
> Of course we would rather have lbas consecutive.

Does anyone know why the block layer does not support
(max_hw_sectors << 9) < PAGE_SIZE ?