Subject: Re: [boost] SIMD implementation of uBLAS
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2013-05-29 09:59:12
On 29/05/13 15:00, Nasos Iliopoulos wrote:
> We are also seeking ways of making the uBLAS expression templates more
> transparent to the compiler so that auto-vectorization can kick in -
> which it does in certain cases and provides a very nice performance
> boost on par with explicitly vectorized libraries.
>
> As a matter of fact I am surprised by the progress of the compilers
> auto-vectorization facilities the last few years, that make me -doubt-
> the need for explicit vectorization any more. The GSOC project will make
> it clear for us. An added benefit on relying on compiler is that future
> vector instructions come for free. A disadvantage is of course the
> non-guarantee that auto-vectorization will work but I find this rarely
> the case.
Yet according to a variety of benchmarks, performance of uBLAS is very
bad when compared to other similar libraries (Eigen, Armadillo, Blitz++,
Blaze, or even our own library NT2) even for simple cases and with
aggressive optimization settings.