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Re: [dm-devel] [PATCH v2 1/1] dm-raid45



On Mon, 2009-12-21 at 09:48 -0700, Dan Williams wrote:
> On Wed, Dec 9, 2009 at 10:47 AM, Heinz Mauelshagen <heinzm redhat com> wrote:
> > On Tue, 2009-12-08 at 17:38 -0700, Dan Williams wrote:
> >> On Thu, Nov 26, 2009 at 6:45 AM,  <heinzm redhat com> wrote:
> >> > From: Heinz Mauelshagen <heinzm redhat com>
> >> >
> >> > Neil et al.,
> >> >
> >> > finally got around to creating a followup (interim) patch, which allows
> >> > for changing the xor algorithn at runtime via the message interface,
> >> > hence allowing to test if the xor unrole optimization around the
> >> > supported algorithms is performing better than the assembler
> >> > optimized one in the kernel.
> >>
> >> Now that perf is available it would be good to get some comparative
> >> cache utilization statistics on the two approaches.
> >
> > I'd appreciate it.
> > Do you have any time to spend on this comparison ?
> >
> 
> I can give it a shot.

Thanks.

>  The easiest way to test would be to export your
> versions via a struct xor_block_template.

Yes, but my recent dm-raid45 patch on dm-devel allows for selection of
the xor routine being used and its parameters..

Fiddling the macros into xor_block_template structs would allow for
testing them with other callers...

>  However, the question I
> have is how do your macros differ from the existing ones in
> include/asm-generic/xor.h?

Those xor data from multiple blocks via sequenced single xor operations
whereas mine does them in one go.

> Can we achieve the same effect by
> extending the ones in include/asm-generic/xor.h to do up to 8 at a
> time?

I don't think so but that's one question to answer.

Thanks,
Heinz

> 
> Thanks,
> Dan
> 
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