[Arm-netbook] RedSleeve - New ARM Linux Distro

[Vladimir Pantelic]

Gordan Bobic wrote:
> Vladimir Pantelic wrote:
>>  Gordan Bobic wrote:
>>
> It's nowhere nearly as clear cut in the case of emulation (soft) vs
> soft-float (VFP with old ABI), as I've explained here:
> http://www.raspberrypi.org/forum/distributions/redsleeve-linux-on-raspberry-pi/#p62612
>
> In a lot of cases soft-float is actually slower than emulation.
>
> Hard-float should be faster in all cases, but it'll only make a
> difference if the code uses a lot of FP.

and if it uses a lot of FP, hand coded (neon) assembly for the time
critical stuff will beat any compiler generated code anyway,
see e.g. FFmpeg/libav

>>  comparing *only* soft vs hard calling convention yields much more
>>  reasonable results:
>>
>>  http://markmail.org/message/to7jc6dx2h7tt7ak
>
> Indeed, on something very FP heavy that doesn't context switch between
> functions much like povray, soft-float is only 5-10% slower than
> hard-float. I would expect soft (fully emulated) to be much slower in
> this case.
>
> But all this will still make no difference in applications that don't
> use FP operations - I wouldn't expect to see any meaningful difference
> between soft, soft-float and hard-float on those.

unless the "soft" ones are using armv5 and an old compiler and the
"hard" ones armv7 and a newer/better compiler