Messages in this thread |  | | Subject | Re: [PATCH] x86: Run checksumming in parallel accross multiple alu's | From | Ben Hutchings <> | Date | Fri, 1 Nov 2013 16:16:52 +0000 |
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On Fri, 2013-11-01 at 12:08 -0400, Neil Horman wrote: > On Fri, Nov 01, 2013 at 03:42:46PM +0000, Ben Hutchings wrote: > > On Thu, 2013-10-31 at 14:30 -0400, Neil Horman wrote: > > [...] > > > It > > > functions, but unfortunately the performance lost to the completely broken > > > branch prediction that this inflicts makes it a non starter: > > [...] > > > > Conditional branches are no good but conditional moves might be worth a shot. > > > > Ben. > > > How would you suggest replacing the jumps in this case? I agree it would be > faster here, but I'm not sure how I would implement an increment using a single > conditional move.
You can't, but it lets you use additional registers as carry flags. Whether there are enough registers and enough parallelism to cancel out the extra additions required, I don't know.
Ben.
-- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked.
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