vectorisation: -Ofast vectorises even better.  (Though the results might be off somewhat)
BTW, this is one of the big issues with the vanila ublas implementation.  I mean that it doesn't vectorise.

On Friday, 22 January 2016, 0:30, "" <> wrote:

From: nasos <>
Subject: Re: [ublas] Matrix multiplication performance
Message-ID: <BLU436-SMTP2214ADFAE38F3F9E1812E2999C30@phx.gbl>
Content-Type: text/plain; charset="windows-1252"; Format="flowed"

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
> 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.