On Tue, 2009-12-08 at 17:38 -0700, Dan Williams wrote:
> On Thu, Nov 26, 2009 at 6:45 AM, <heinzm@xxxxxxxxxx> wrote:
> > From: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
> >
> > 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 ?
> The assembly
> routines make an attempt to avoid polluting L2 (however the memcpy's
> into the cache do not).
>
> > If we can prove my findings rigth, we could move those into
> > the crypto subsystem xor.
> >
> > Syntax:
> > -------
> > dmsetup message $MappedDevice 0 xor $Algorithm $Chunks
> >
> > $MappedDevice = whatever name you picked during creation
> > $Algorithm = { "xor_8", "xor_16", "xor_32", "xor_64", "xor_blocks" }
> > $Chunks = 2..N # N being the amount of stripes (eg. 5 with 5 disks)
> >
> > Patch applies to clean mainline git 2.6.32-rc8.
> >
> > Regards,
> > Heinz
> >
> > Signed-off-by: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
> > ---
> > drivers/md/Kconfig | 9 +
> > drivers/md/Makefile | 2 +
> > drivers/md/dm-memcache.c | 301 +++
> > drivers/md/dm-memcache.h | 68 +
> > drivers/md/dm-raid45.c | 4720 ++++++++++++++++++++++++++++++++++++++++
>
> Where did the investigation of reusing md/raid5.c [1] end up? This
> would simultaneously enable hardware accelerated raid6 for dmraid.
Not far. Got distracted by other activities and haven't heard back from
Neil after submitting this dm-raid45 patch (which makes it simple to
test various parameter sets w/o reloading mappings).
Heinz
>
> --
> Dan
>
> [1] http://marc.info/?l=dm-devel&m=124567352518676&w=2
>
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