Why didn't Larrabee fail?
O.K. fucking major rant below. Disclaimer I worked for an vendor selling large
quantities pretty much anything in the HPC space at the time KNC came to market
and I now work for a different (larger) HPC vendor.<p><pre><code>  When I say &quot;Larrabee&quot; I mean all of Knights, all of MIC, all of Xeon Phi, all of
  the &quot;Isle&quot; cards - they&#x27;re all exactly the same chip and the same people and the
  same software effort. Marketing seemed to dream up a new codeword every week,
  but there was only ever three chips:
  
      Knights Ferry &#x2F; Aubrey Isle &#x2F; LRB1 - mostly a prototype, had some performance gotchas, but did work, and shipped to partners.
      Knights Corner &#x2F; Xeon Phi &#x2F; LRB2 - the thing we actually shipped in bulk.
      Knights Landing - the new version that is shipping any day now (mid 2016).
</code></pre>
I can kind of see what the author is getting at here but it&#x27;s worth reminding
general readers KNL is a wildly different beast from KNF or KNC.<p>1. It&#x27;s self hosting, it runs the OS itself&#x2F; there is no &quot;host CPU&quot;.<p>- Yes KNC ran it&#x27;s own OS but it was in the form of a PCI-E card which still had
to be put into a server of some kind.<p>- Yes KNL is slated to have PCI=E card style variants but the self hosting
variants are what will be appearing first and I honestly don&#x27;t think the PCI-E
variants will gain much if any market traction.<p>2. It features MCDRAM which provides a massive increase in total memory
bandwidth within the chip. Arguably this is necessary with such large core
counts.<p>3. Some KNL variants will have Intel&#x27;s Omni-Path interconnect directly
integrated which should further drive down latency in HPC clusters.<p><pre><code>  Behind all that marketing, the design of Larrabee was of a CPU with a very wide
  SIMD unit, designed above all to be a real grown-up CPU - coherent caches,
  well-ordered memory rules, good memory protection, true multitasking, real
  threads, runs Linux&#x2F;FreeBSD, etc.
</code></pre>
Here&#x27;s an interesting snippet, drop &quot;Larrabee&quot; from the above and replace it
with &quot;Xeon&quot;. I&#x27;m just wanting the point here that the Xeon and Xeon Phi product
lines are only going to look more similar over time. For a while now the regular
Xeons have been getting wider. Which is to say more cores and fatter vector
units. The Xeon Phi line started out with more cores but is having to drive the
performance of those cores up. Over time we&#x27;re going to see one line get
features before the other e.g. AVX512 is in KNL and will be in a &quot;future Xeon&quot;
(Skylake). And it&#x27;s widely rumored that &quot;future Xeons&quot; will support some form of
non-volatile main memory, something not on any Xeon Phi product roadmap today.
The main differentiator will be that Xeon products need to continue to cater to
the mass market whereas Xeon Phi can do more radical things to drive compute
intensive workloads (HPC).<p><pre><code>  Larrabee, in the form of KNC, went on to become the fastest supercomputer in the
  world for a couple of years, and it&#x27;s still making a ton of money for Intel in
  the HPC market that it was designed for, fighting very nicely against the GPUs
  and other custom architectures.
</code></pre>
Yes at the time Tianhe 2 made it&#x27;s debut it was largely powered by KNC and it
placed at number 1 on the top 500.<p>Did KNC as a product make a lot of money for Intel? Probably not. Yes they
shipped a lot of parts for Tianhe 2 but for other HPC customers, not so much. At
the time putting a KNC card against a Sandy Bridge CPU it wasn&#x27;t leaps and
bounds faster. Yes you&#x27;re always going to have to re-factor when making such
a change in architecture but the gains just weren&#x27;t worth it in most cases. Not
to say there haven&#x27;t been useful deployments of KNC that have contributed to
&quot;real science&quot;, but it was not a wild success by any measure.<p>As for &quot;fighting very nicely against the GPUs and other custom architectures&quot;,
I don&#x27;t think so. When KNC got to the market Nvidia GPUs already had a pretty
well established base in the HPC communities. Many scientific domains already
had GPU optimized libraries users could pick off the self and use. Whilst KNC
was cheaper than the Kepler GPUs on the market at the time it wasn&#x27;t much
cheaper. Again back to regular Xeons, for a cost&#x2F; performance benefit KNC wasn&#x27;t
worth it for a lot of people.<p><pre><code>  Its successor, KNL, is just being released right now (mid 2016) and should do
  very nicely in that space too.
</code></pre>
I do agree with this, KNL is going to do very well. There are whole systems
being built with KNL rather than large clusters with some KNC or some GPUs.<p><pre><code>  1. Make the most powerful flops-per-watt machine.
</code></pre>
Not sure what is mean here, most efficient machine in the top 10? Tianhe 2 is
not an efficient machine by any stretch of the imagination. For reference here&#x27;s
the top 10 of the Green 500 for when Tianhe 2 placed as number 1 on the Top
500.<p><a href="http:&#x2F;&#x2F;www.green500.org&#x2F;lists&#x2F;green201306" rel="nofollow">http:&#x2F;&#x2F;www.green500.org&#x2F;lists&#x2F;green201306</a><p><pre><code>  SUCCESS! Fastest supercomputer in the world, and powers a whole bunch of the
  others in the top 10. Big win, covered a very vulnerable market for Intel, made
  a lot of money and good press.
</code></pre>
Yes KNC provides the bulk of the computing power for Tianhe 2 but at the time of
writing of the above is number 2, not number 1. Secondly that is the ONLY
machine in the top 10 that uses KNC AT ALL.