Messages in this thread | | | Date | Thu, 16 Aug 2012 19:22:51 +0200 | From | Johannes Stezenbach <> | Subject | Re: [GIT PULL] Update LZO compression |
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On Thu, Aug 16, 2012 at 12:48:49PM -0400, Jeff Garzik wrote: > On 08/16/2012 12:20 PM, Andi Kleen wrote: > >>If you think a little bit, I bet you could come up with a solution that > >>operates at cacheline-aligned granularity, something that would be _even > >>faster_ than simply fixing the code to do aligned accesses. > > > >Cache aligned compression is unlikely to compress anything at all. > >Compression algorithms are usually by definition unaligned. > > Sure it's a bitstream, but that does not imply the impossibility of > reading data in in an word-aligned manner. > > Maybe cache-aligned is ambitious, because of resultant code bloat, > but machine-int-aligned is doable and reasonable.
Well, I for one would be content if the old and new lzo versions could be merged based on CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS.
(Assuming that the slowdown on ARM is due to unaligned access, since the old version also uses get/put_unaligned, is the new version actually using more unaligned accesses?)
Johannes
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