[Beowulf] massive parallel processing application required
James.P.Lux at jpl.nasa.gov
Thu Feb 1 16:43:34 EST 2007
At 07:40 AM 2/1/2007, Mark Hahn wrote:
>>Not true. Distributed computing is more and more mainstream. I think too
>oh, one other snide comment about grid: I suspect the grid-fad could
>not have happened without the fraud perpetrated by worldcom and others during
>the internet bubble. in those days, it was popular to claim that the network
>was becoming truely ubiquitous and incomprehensibly fast. for instance:
In the long run, ubiquitous and fast IS going to be true (however,
latency is something you can't get around... speed of light and all
that). As long ago as 1993, I was at a conference where a speaker
from AT&T commented that historical telecom pricing methods (longer
distances cost more) were obsolete, since the dominant cost was in
the termination, with, even then, a gross oversupply of fiber across
the Atlantic. Hence the availability of cheap flat rate long
distance (5c a minute anywhere, anytime).. the bulk of the system is
no longer capacity limited.
>I don't know about you, but in the 6 years since then, my home net
>connection has stayed the same speed, possibly a bit more expensive.
Interestingly, they've just rolled out FiOS (fiber to the home) in my
area, which is a HUGE jump in potential bandwidth from the existing
DSL or Cable Modem delivery methods. And, moderately competitive in
price (5 Mbps is $40/month, including the bundled ISP kinds of
features). What's fascinating is the faster tiers.. you can get 15
Mbps down/2 up for $50/mo and 30 M down/5 up for $180
Granted, these are consumer offerings and have all the usual network
congestion caveats, but hey, at least they are offering 30 Mbps for
the last mile, which is quite impressive.
>desktop/LANs are still mostly at 100bT, with 1000bT in limited use.
But that's more driven by replacement cycles and the lack of real
demand for faster speeds to the desktop. If your facility has a 1.5
Mbps pipe to the internet, giving users a 1 Gb/s won't change their
performance much compared to 100 Mb/s. There's also a wiring
infrastructure issue. While desktops are typically replaced on a 3
year cycle, the wiring infrastructure cycles through a bit slower,
especially in smaller businesses and residential (that is, I'm not
likely to start ripping out the drywall to replace the Cat 5 wiring I
put in back in 1998)... and frankly, since right now, I have maybe
700 kbps at home to the internet (one way), and then a wireless
connection from laptop to home network, there's not much to be gained
by improving the home wiring infrastructure. (If I go with the FiOS
offering though, that may prompt some re-evaluation)
Likewise, a small business with half a dozen or a dozen desktops and
a couple servers isn't going to see a huge benefit from faster
networking, because they're throttled by the server's disk speed,
more than anything else. (assuming they're not hosting a big website, etc.)
So, you're looking at GigE making a difference in two
areas: replacing cable TV (all those 20 Mbps HDTV streams) and in
big companies. But even in big companies, GigE to the desktop
doesn't necessarily buy you much, if you're all competing for the
same server resources.
>I do notice that grabbing large files off the net (ftp, RPMs, etc)
>often runs at O(MBps) which is about a 10x improvement over the past
>10-15 years. so the doubling time turns out to be more like 3 years
>rather than 9 months.
Which is probably consistent with equipment refurbishment cycles.
> in-cluster networking has improved somewhat faster, but not
> dramatically so.
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James Lux, P.E.
Spacecraft Radio Frequency Subsystems Group
Flight Communications Systems Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
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