linux-kernel - RE: [PATCH] x86: Run checksumming in parallel accross multiple alu's

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Date:	Fri, 1 Nov 2013 16:18:50 -0000
From:	"David Laight" <David.Laight@...LAB.COM>
To:	"Neil Horman" <nhorman@...driver.com>,
	"Ben Hutchings" <bhutchings@...arflare.com>
Cc:	"Doug Ledford" <dledford@...hat.com>,
	"Ingo Molnar" <mingo@...nel.org>,
	"Eric Dumazet" <eric.dumazet@...il.com>,
	<linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>
Subject: RE: [PATCH] x86: Run checksumming in parallel accross multiple alu's

> 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.

I think you need 3 instructions, move a 0, conditionally move a 1
then add. I suspect it won't be a win!

If you do 'win' it is probably very dependent on how the instructions
get scheduled onto the execution units - which will probably make
it very cpu type dependant.

	David




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