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<p>Correct me if I'm wrong, but it looks like all these benchmarks
are for single threaded applications. I don't see any refences to
MPI or OpenMP or other threading method in the compiler,
optimization and invocation notes. The only parallelism I see is
in the use of AVX2 in the 2016 results, and some references to
SIMD in the 2012 results. <br>
</p>
<p>So regardless of the number of cores in each test system, what
the benchmarks are really comparing is single core performance
between a 2.3 GHz AMD Opteron and a 2.4 GHz. Intel Xeon. Is that
correct? </p>
<p>I'm assuming the starting source code is exactly the same in each
case, too. <br>
</p>
<p>If so, those results aren't surprising. Since systems started
going multi-core, the performance has really come from adding
parallelism to your programs using threads or message-passing, or
taking advantage of the larger vector processing capabilities that
get added to each successful generation of processors. If these
benchmarks were rewritten to optimize them for data parallelism
and to make sure the data was properly aligned for the vector
registers, I'm sure the newer processor would show better
performance. <br>
</p>
<p>
<blockquote type="cite">So glad that we have thousands of Phi's...</blockquote>
</p>
<p>I wouldn't be so glad. You're still going to have to rewrite your
code as mentioned above to get any meaningful performance. <br>
</p>
<p>When Intel first started marketing the Xeon Phi, they emphasized
that you wouldn't need to rewrite your code to use the Xeon Phi.
This was a marketing moving to differentiate the Xeon Phi from the
NVIDIA CUDA processors. That may have been a true statement, but
it didn't mention anything about performance of that existing
code, and was, frankly, very misleading. The truth is, if you
don't rewrite your code, you're not going to see much (relatively
speaking) of a performance improvement, and when you do rewrite
your code to optimize it for the Xeon Phi, you'll also see amazing
speed ups on regular Xeon processors.</p>
<p> I've seen several presentations where speed ups of 5x, 10x,
etc., on regular Xeons just through optimizing the code to be more
thread- and vector- friendly. Some improvements were so
significant, they make you ask if the Xeon Phi was even needed.
These are the first gens I'm talking about, I imagine the KNL will
make a more compelling argument for the Phi. <br>
</p>
<p>If you pay attention to Intel's marketing and the industry news
the past couple of years, you will have noticed that Intel has
been promoting "code modernization" efforts, saying all codes need
to be modernized to take advantage newer processors, while that is
certainly true, "code modernization" is just a euphemism for
"rewrite your code". This is Intel backpedaling on their earlier
statements that you don't need to rewrite your code to take
advantage of a Xeon Phi, without actually admitting it. <br>
</p>
<pre class="moz-signature" cols="72">Prentice </pre>
<div class="moz-cite-prefix">On 08/16/2016 04:35 AM, Stu Midgley
wrote:<br>
</div>
<blockquote
cite="mid:CAEM1RsW+Q+=CFWqXk+gPeiKs_LiZCxzj3_iYFjsUXxsOVo20QA@mail.gmail.com"
type="cite">
<div dir="ltr">
<div style="font-size:12.8px;line-height:normal"><a
moz-do-not-send="true"
href="https://www.spec.org/cpu2006/results/res2016q2/cpu2006-20160308-39354.html"
target="_blank">https://www.spec.org/cpu2006/<wbr>results/res2016q2/cpu2006-<wbr>20160308-39354.html</a><br>
</div>
<div style="font-size:12.8px;line-height:normal"><a
moz-do-not-send="true"
href="https://www.spec.org/cpu2006/results/res2012q4/cpu2006-20121108-25077.html"
target="_blank">https://www.spec.org/cpu2006/<wbr>results/res2012q4/cpu2006-<wbr>20121108-25077.html</a></div>
<div style="font-size:12.8px;line-height:normal"><br>
</div>
<div style="font-size:12.8px;line-height:normal">Its like no
progress has been made. So glad that we have thousands of
Phi's...</div>
<div><br>
</div>
-- <br>
<div class="gmail_signature" data-smartmail="gmail_signature">Dr
Stuart Midgley<br>
<a moz-do-not-send="true" href="mailto:sdm900@sdm900.com"
target="_blank">sdm900@sdm900.com</a></div>
</div>
<br>
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</pre>
</blockquote>
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