From: nasos <nasos_i@hotmail.com>
To: ublas@lists.boost.org
Subject: Re: [ublas] Matrix multiplication performance
Message-ID: <BLU436-SMTP2214ADFAE38F3F9E1812E2999C30@phx.gbl>
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Michael,
please see below

On 01/21/2016 05:23 PM, Michael Lehn wrote:
> Hi Nasos,
>
> first of all I don?t want to take wrong credits and want to point out
> that this is not my algorithm.  It is based on
>
> http://www.cs.utexas.edu/users/flame/pubs/blis2_toms_rev3.pdf
>
> https://github.com/flame/blis
>
> For a few cores (4-8) it can easily made multithreaded.  For
> many-cores like Intel Xeon Phi this is a bit more
> sophisticated but still not too hard.
Setting up Phis is indeed an issue, especially because they are "locked"
with icpc. Openmp is working properly though.

> The demo I posted does not use micro kernels that exploit SSE, AVX or
> FMA instructions.  With that the matrix product is on par with Intel
> MKL.  Just like BLIS. For my platforms I wrote
> my own micro-kernels but the interface of function ugemm is compatible
> to BLIS.
>
If you compile with -O3 I think you are getting  near optimal SSE
vectorization. gcc is truly impressive and intel is even more.