Re: [Qemu-devel] [RFC PATCH 0/6] target/ppc: convert VMX instructions to use TCG vector operations

[Mark Cave-Ayland]

On 10/12/2018 13:04, Aleksandar Markovic wrote:

> On Dec 7, 2018 9:59 AM, "Mark Cave-Ayland" <address@hidden>
> wrote:
>>
>> This patchset is an attempt at trying to improve the VMX (Altivec)
> instruction
>> performance by making use of the new TCG vector operations where possible.
>>
> 
> Hello, Mark.
> 
> I just want to say that I support these efforts. Very interesting, it can
> bring significant improvements for multimedia intensive emulations. But,
> even more important, we can see new tcg vector interface in action,
> possibly suggest improvements, extensions.
> 
> I would just like to ask you to add some performance comparisons, if
> possible. Very simple tests would be sufficient.
> 
> Thanks again for this series!

Thanks Aleksander! In my local tests I haven't done much in the way of 
benchmarking,
other than to check the output of the disassembler to confirm that the x86 
vector
opcodes are being used. Given that only a small number of TCG vector operations 
are
currently suitable for use with the VMX code, then I would expect certain 
artificial
benchmarks to show improvements e.g. with the logical ops but there was 
certainly
nothing noticeable in normal usage with my OpenBIOS test images.

I agree with you that having a second implementation other than ARM will help 
provide
ideas as to how the vector interfaces can be evolved to support more operations 
in
future.


ATB,

Mark.