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Re: wiki page udpates

On Tue, Nov 06, 2018 at 07:36:36PM +0000, Richard Earnshaw wrote:
> > 
> >> - does earmv7 run faster than earmv6 on a RPI2/3?  How much?
> > 
> > Not much of a difference.
> Really?
> Firstly, I'd expect an earmv7 port to default to hw FP, so anything with
> FP should be significantly faster (there are FP variants of armv6, but
> they were relatively rare (maybe the pi is an exception, I forget).

We are talking about earmv6hf vs. earmv7hf. So both are using hardware
floating point.

> Secondly, the cache in v7 is PIPT, so there's no need to do any horrible
> page colouring/flushing on every context switch; that should make a
> notable difference to overall performance.  I think there might have
> been other changes to the cache MMU management ops as well to improve
> performance.

Sure, but the real world difference is small for most things.

> Many v7 chips also have Neon SIMD extensions, which can also improve
> performance of some key algorithms if run-time detection is supported (I
> believe the v7 versions of the Pi have this).

Indeed, but that's independent of building as v6 or v7.

                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."

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