[PATCH 01/11] async_tx: don't use src_list argument of async_xor() for dma addresses

Dan Williams dan.j.williams at intel.com
Sat Nov 15 11:42:27 EST 2008


On Thu, Nov 13, 2008 at 8:15 AM, Ilya Yanok <yanok at emcraft.com> wrote:
> Using src_list argument of async_xor() as a storage for dma addresses
> implies sizeof(dma_addr_t) <= sizeof(struct page *) restriction which is
> not always true.
>
> Signed-off-by: Ilya Yanok <yanok at emcraft.com>
> ---

I don't like the stack space implications of this change.  Especially
for large arrays we will be carrying two 'src_cnt' size arrays on the
stack, one from MD and one from async_tx.  However, I think the
current scheme of overwriting input parameters is pretty ugly.  So, I
want to benchmark the performance implications of adding a GFP_NOIO
allocation here, with the idea being that if the allocation fails we
can still fallback to the synchronous code path.

--
Dan



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