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



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 ?

>  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 redhat com>
> > ---
> >  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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> dm-devel mailing list
> dm-devel redhat com
> https://www.redhat.com/mailman/listinfo/dm-devel


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