Lyndon Nerenberg (VE6BBM/VE7TFX) wrote:
From last week's ACM Technews ...
Why Desktop Multiprocessing Has Speed Limits
Computerworld (10/05/09) Vol. 43, No. 30, P. 24; Wood, Lamont
Despite the mainstreaming of multicore processors for desktops, not
every desktop application can be rewritten for multicore frameworks,
which means some bottlenecks will persist. "If you have a task that
cannot be parallelized and you are currently on a plateau of
performance in a single-processor environment, you will not see that
task getting significantly faster in the future," says analyst Tom
Halfhill. Adobe Systems' Russell Williams points out that performance
does not scale linearly even with parallelization on account of memory
bandwidth issues and delays dictated by interprocessor communications.
Analyst Jim Turley says that, overall, consumer operating systems
"don't do anything smart" with multicore architecture. "We have to
reinvent computing, and get away from the fundamental premises we
inherited from von Neumann," says Microsoft technical fellow Burton
Smith. "He assumed one instruction would be executed at a time, and
we are no longer even maintaining the appearance of one instruction at
a time." Analyst Rob Enderle notes that most applications will operate
on only a single core, which means that the benefits of a multicore
architecture only come when multiple applications are run. "What we'd
all like is a magic compiler that takes yesterday's source code and
spreads it across multiple cores, and that is just not happening,"
says Turley. Despite the performance issues, vendors prefer multicore
processors because they can facilitate a higher level of power
efficiency. "Using multiple cores will let us get more performance
while staying within the power envelope," says Acer's Glenn Jystad.
http://www.computerworld.com/s/article/342870/The_Desktop_Traffic_Jam?intsrc=print_latest
'The usual <talking through their anatomy> suspects'....
But they miss the point. Work will always be foudn for 'faster' devices, but the
majority of the 'needed' benefit has been accomplished until entirely new
challenges surface. Computer games and digital video special-effects are just candy.
Even a dual-core allows moving the overhead, housekeeping, I/O, interrupt
servicing, et al out of the way of a single-core-bound application. OS/2 Hybrid
Multi-Procesing - even with unmodified Win 3X era apps.
Beyond that it matters little.
Given a 'decent' (not magical)[1] OS, and environment, the apps that actually
*matter* to 99% of the population are more than fast enough on the likes of a
VIA C6 --> nano/Geode/Atom [2], embedded Ppc [3], or even an ARMish single-core
[4]- with or without DSP etc. on-substrate.
Faster storage and networks now matter far more than faster local CPU.
The ratio of these 'goodies', and their benefits to the population in general
to the count of supercomputers [5] and near-real-time video-stream processors
[6] is - and will remain - extremely lopsided in favor of the small 'appliance'.
Those hyping multi-multi core for the consumer 'PC" market are locked ino an
obsolete behaviour pattern.
Lower power consumption, smaller form-factor, better display and input interface
faster networking is where the need lies.
Nothing yet shipped can match the effectiveness of an experienced Wife or
Personal Assistant (human) at the other end of an ordinary phone line when (s)he
has *anticipated* your needs and called you *before* you recognized the need
yourself.
Code THAT into silicon, teach it to cook, and you still have a lousy
bed-partner...
Bill Hacker
[1] Anything not horribly wasteful (eg - not Windows), such as Plan9, any *BSD,
the leaner Linux (Vector/Slackware), Haiku - all make a more than fast enough
desktop on any single-core of 700 MHz or better, even if dragging X-Windows and
the like around as a boat-anchor.
[2] Laptops amd Netbooks
[3] Embedded high-end. Game boxen, Ford and other motor cars
[4] A large percentage of PDA's and telecoms handhelds
[5] Devilishly hard to substitute for, SETI et al notwithstanding, but needed in
relatively small numbers vs, for example, a mobile phone or automobile
fuel/pollution reduction system.
[6] Given the preponderance of dreck spewed from television and cinema,
civilization could well be better-off if all such devices on the planet went on
a long holiday and humans returned to actually paying attention to one another.
