Re: a dozen cpu's on a chip

On Tue, 13 May 2008 08:05:12 -0700 (PDT), panteltje@xxxxxxxxx wrote:

On 8 mei, 04:48, John Larkin
<jjlar...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
http://www.eetimes.com/news/latest/showArticle.jhtml;jsessionid=CESEX...

I bet we'll see 256 one of these days.

John

It is of course completely of-topic, but jus tto contribute for
test :-) to
the noise, I am sure I have seen a 512 core chip several years ago.

The problem is what to do with > 6 cores.
As you al probably know Sony PS3 has a Cell processor
with one big and 6? small 'helper' processors.
Now in a multimedia application, or networking, two ways,
say signal processsing decryption decoding graphics that
will maybe use 4 cores.
It is not easy to slit a program over more then one core.
Even if threaded, it makes not always sense,
I have written threaded programs where some threads use very few
resources,
running those on a separate core woul make little sense,
Some multi media stuff uses no threads at all (Linux mplayer IIRC),
while others, xine media player for example _is_ threaded.
And this is from the POV of embedded.
Now sure, you could run some FPGA synthesize on one core,
PCB routing on the other, SPICE on a third.. however how often
do you use it at the same time.
So, and I am not even thinking Microsoft, they only have binaries for
X86 of
their OS, but the software that takes full advantage of so many cores
for a _general purpose_ OS, has, as far as I know, not been invented
yet.
And are sequential cores always the best solution? Not sure,
in the above example the decryption could be done faster by FPGA (1
clock) perhaps.

So, unless they come up with a software solution that makes full use
of those cores, perhaps the only other option is to try to up the
clock speed,
new techniques to reduce power consumption are mentioned here and
there.


My XP, not doing much right now, claims to be running 31 processes.
Add in maybe another 30 device drivers, tcp/ip stacks, and file
managers, and it would keep a 64-core cpu mostly employed.

Again, it's not about speed, although that would be improved too.


So how about 10 GHz or 20 GHz clock, would that not make more sense?


The speed thing is hitting the wall, which is why everybody is going
multicore.


John


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