Re: [PATCH 7/10] i386 sg: add support for chaining scatterlists

[Herbert Xu]

Jens Axboe <jens.axboe@xxxxxxxxxx> wrote:
> 
> diff --git a/include/asm-i386/scatterlist.h b/include/asm-i386/scatterlist.h
> index d7e45a8..794b68c 100644
> --- a/include/asm-i386/scatterlist.h
> +++ b/include/asm-i386/scatterlist.h
> @@ -8,8 +8,11 @@ struct scatterlist {
>     unsigned int       offset;
>     dma_addr_t         dma_address;
>     unsigned int       length;
> +    struct scatterlist *next;
> };

BTW, the crypto layer's scatterlist already has a chaining mechanism
using the existing structure.  The only difference is that the chained
pointer is stored inside the 'struct page *' rather than a new pointer.
Its existence is flagged by a zero value in the length field.

Now I'm not super-religious about this but we should at least consider
whether forking out 4 bytes in every scatterlist member is worthwhile
investment when we can use 12 bytes at the end instead.

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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