Re: Neon Support in kernel

On 26 January 2011 12:12, Dave Martin dave.martin@linaro.org wrote:

Hi Vijay,

On Sat, Jan 22, 2011 at 9:59 AM, Vijay Kilari vijay.kilari@gmail.com wrote:

...

Hello Dave,

Thanks for this info.

I have few more queries after looking at the results of memset on A9 & A8. I agree that externel bus speed matters in comparision across platforms.

1. Why memset is performance is good on A8 than A9?. any justification?

I've CC'd the linaro-toolchain list who have been working on this topic and may be able to provide you with more information.

Unfortunately we don't know why Neon was a bad idea for memset etc on A9, it's just the tests show it being worse and the advice we get says to avoid it - we've just not got an explanation.

The test code is trivially simple for the cases I tried.

Dave