Re: [PATCH] scsi: avoid to fetch scsi host template instance in IO path

Christoph Hellwig
2020-03-02T13:15:45Z

On Mon, Mar 02, 2020 at 10:58:55AM +0000, John Garry wrote:
> On 28/02/2020 09:33, Ming Lei wrote:
>> scsi host template struct is quite big, and the following three
>> fields are needed in SCSI IO path:
>>
>> - queuecommand
>> - commit_rqs
>> - cmd_size
>
> Would it have been nearly as good to reorganise Scsi host template
> structure to ensure that these are adjacent?
>
> I say nearly, as it avoids the shost->hostt read.

That would be worth trying. Replicating function pointers out of
read-only data structures generally isn't a very good idea.