[FoRK] Mobile chipsets, Re: FoRK Digest, Vol 131, Issue 5

Stephen D. Williams sdw at lig.net
Sun Aug 10 12:25:24 PDT 2014

BTW, current mobile hardware, just considering the CPU and CPU cores, is theoretically capable of well over 150 gigaops / sec at 
shipping clock speeds.  Many of those can be float and/or double.  That is going to go up drastically soon.  Whether a particular 
application can take advantage of much of that is always a key question, but many could substantially.


On 8/10/14, 12:09 PM, Stephen D. Williams wrote:
> Sort of.  We have or will have many cores soon.  Massive number crunching has been moved to within millimeters of where it is 
> needed, running <1v, a few watts at peak but almost nothing in between, and communicated to at 4GBps per channel bundle (with at 
> least 2-3 of these links per system) now and growing.  A current mobile chipset has 4 scalar cores with 4 SIMD cores (with some 
> overlap in execution), 4 GPU cores (destined to grow a lot), a reasonably powerful pair of DSPs, various hardware processing 
> blocks that do heavy-lifting bitmap scaling, transform, composite, and codecs.
> All of that is going to grow incrementally, perhaps doubling every several years, along with ever more efficient power usage.  And 
> it will be augmented in various ways with ever more powerful and lower power hardware.  We've been at a stabilization point.  Now 
> we'll get into the interesting processing.  I can't comment on some interesting developments yet...
> And all of that is in a typical mobile phone/tablet in a chipset that is less than a tenth of the overall cost.  Servers will 
> inevitably be clusters of those, probably often cast offs from last year's mobile device production.
> Devices are already approaching or slightly surpassing 16 cores, but only part of them share the same memory bus, or share it in 
> symmetric ways.
> While these new chipsets could actually be easily connected in a 3D torus in a high bandwidth/low latency supercomputer 
> configuration, few applications need that.  The many-core depth in new systems will mostly be used for 3D, computational imaging, 
> advanced sensing, ML, and other AI algorithms.  Also, as is well known, more cores can run at slower clock rates for the same 
> workload to use far less power.  This is part of what justified quadcore mobile processors initially.  Although coordination / 
> fanout causes some overhead, it is a key effect.  There is also the fast/slow core strategy, although I don't think it is doing as 
> well.
> These are some key differences from what people expected I think:
> - Core specialization plus powerfully symmetric processors would drastically outperform symmetric general purpose processors
> - Mobile rather than powerful server / desktop hardware would be the most important computational platform, improving so rapidly 
> it is also viable for server & desktop use.
> - Power usage / heat dissipation and overall efficiency would turn out to be the most important aspect of consumer-owned devices 
> (mobile) and servers (server density / power usage).
> - Mobile and cloud servers, where Unix/Linux quickly bubbled to the top, would become overwhelmingly important, getting on a track 
> to completely negating and obsoleting desktops except as cheap web portals and file servers.  For traditional desktop app usage, 
> there is a "good enough" hardware capability level that mobile devices have probably already surpassed.  The rest is a simple 
> matter of programming and connectivity.  The connectivity is already done: HDMI, USB3, PCIe, 4 lane MIPI, etc.  Thunderbolt would 
> be nice, perhaps via PCIe or many bidirectional MIPI lanes.
> - The rise in probabilistic algorithms, ML, computational imaging in addition to 3D everywhere.
> - That Javascript optimization engines, and other web related technology such as pNACL and emscripten, along with WebGL and soon 
> WebCL, would catapult web development range well into and often past what desktop apps can offer, yet run on any device, including 
> most mobile and embedded devices.  And that these would range down to a few dollars.
> - The rise in resilient cloud processing systems which negates the value of complex resilient processors, memory, or RAID or other 
> storage.  Cheap cells that are easily sloughed off and grown anew rule.  Organic computing in a different sense.
> Nice really.
> Stephen
> On 8/10/14, 10:06 AM, Joseph S. Barrera III wrote:
>> On Sun, Aug 10, 2014 at 6:32 AM, Eugen Leitl <eugen at leitl.org> wrote:
>>> Wrong about what?
>> ​Wrong about a single OS and/or memory system needing to scale to more than
>> 16 or so processors. OK, maybe 96.​
>> Everything else is done with JBOC (just a bunch of cpus) networked together.
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