Re: [PATCH 03/13] scsi: unify allocation of scsi command and sensebuffer

[FUJITA Tomonori]

On Mon, 25 May 2009 18:45:25 -0700
Roland Dreier <rdreier@xxxxxxxxx> wrote:

>  > Ideally there should be a MACRO that is defined to WORD_SIZE on cache-coherent
>  > ARCHs and to SMP_CACHE_BYTES on none-cache-coherent systems and use that size
>  > at the __align() attribute. (So only stupid ARCHES get hurt)
> 
> this seems to come up repeatedly -- I had a proposal a _long_ time ago
> that never quite got merged, cf http://lwn.net/Articles/2265/ and
> http://lwn.net/Articles/2269/ -- from 2002 (!?).  The idea is to go a

Yeah, I think that Benjamin did last time:

http://www.mail-archive.com/linux-scsi@xxxxxxxxxxxxxxx/msg12632.html

IIRC, James didn't like it so I wrote the current code. I didn't see
any big performance difference with scsi_debug:

http://marc.info/?l=linux-scsi&m=120038907123706&w=2

Jens, you see the performance difference due to this unification?


Personally, I don't fancy __cached_alignment__ annotation much. I
prefer to leave it behind a memory allocator.


> step further and create a __dma_buffer annotation for structure members.


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