24 Oct
1999
24 Oct
'99
6:25 p.m.
At 07:56 PM 10/24/99 -0700, you wrote:
Excuse me? Could you please back up this assertion
with data? After all,
at -some- point, all these busses have to get their data into/out of the CPU,
right? And -that- is a "bottleneck" for sure... (Sure, you can have
channel-to-channel I/O, but most aps are not just shuffling bits.)
Well ... I have some experience with high-speed switches and crossbars
in parallel supercomputers (as a user). The fallacy in your thinking is
that you believe that moving data around is not "processing". You still
think that the real processing takes place only at the cpu. Matter of fact
is that, in the real world, as data goes through each driver/buffer and
process in the OS on its way to the process that will actually do something
with it (i.e., actual "integer-op-related" cpu time) there are usually several
large block transfers. If all of this can happen without hogging the cpu
(and you need hardware to do it) you can bet that the corresponding machine
will be many times faster than a machine with a PCI bus.
I once read that the average number of moves for net data (after it is in
memory) for data from input through tcp/ip stack through OS through
application is on the order of 4.x ... I think in some Sun literature...