Text 23781, 77 rader
Skriven 2006-11-18 11:14:37 av Jeff Guerdat (1:123/789.0)
  Kommentar till text 23768 av ED VANCE (1:123/140)
Ärende: Dual Core CPUs
======================
ED VANCE -> ALL wrote:

 EV> I suppose what I do probably only uses one of the two CPUs usually.

Yes and no.  If you watch the performance graph in Task Manager set up to show
each CPU individually, you'll see that the CPUs share the load.  It's
relatively rare to see one CPU soar with the other sitting near zero.  That
said, the typical app is "single-threaded", meaning that it will not run twice
as fast on dual cpus.  The OS, however, is "multi-threaded", meaning that it
will utilize all cpus for best performance.  Of course, typically the OS is a
light load compared to Excel number crunching or applying a filter to a large
digital image.

There's a couple of observations that may help.  1) As you look for new
applications, take the time to find if they're multi-threaded.  You can only
wait so fast in a word processor so that won't make much difference but a image
processing package may get a large jump in performance.  I also note that DVD
Shrink uses multiple CPUs, "shrinking" the time to process a DVD to about an
hour compared to 2 hours for a single CPU.  2) The computer will be more
responsive when loaded since you have more cpu cycles available to not only do
the job you're processing but also do other work at the same time.  One could
apply the same observations when using SCSI vs. IDE - one will help the overall
system performance by not allowing things to bog the system down.  You have to
experience it to see the difference and, once you're used to it, you'll have a
hard time going back to the lesser models...

 EV> My old 486 box gives me trouble when I use a W3.1 program to print
 EV> something out because even IF I click on something while the computer is
 EV> sending code to the printer I'll get a incomplete print job.

 EV> I have to do something else while a print job is going on, such as,
 EV> reading, turning on either the W95 laptop or the XP box and reading QWK
 EV> messages or something else until the print job is over on the 486 box.

 EV> So I have been conditioned NOT TO DO MORE THAN ONE THING AT A TIME. ;-[

Well, part of that is to GET RID OF THE CLUNKERS!  ;)  It may be that the OS on
the 486 is the problem and can't properly handle the old application (and all
that it entails) as well as anything else - basically schlock multitasking
capabilities.  I'd wager that using the same app on your new box wouldn't do
that, partly due to the CPU capabilities as well as the OS.

 EV> With the XP box with Dual CPUs I figure I could probably do something
 EV> else while burning a CD or DVD but I haven't tried it out.

I do all the time and have for years.  With today's optical drives supporting
buffer underrun protection, it's basically a moot point.  I do note that
IDE/SATA still has the pregnant pauses when reading a new disc in, say, a CDROM
drive but, since you're burning a disc, that's also probably a moot point for
you assuming you don't have multiple CD/DVD drives.  I much prefer SCSI drives
for this reason but I've been moving away from them.  I wonder how a USB or
FireWire optical drive handles this?

 EV> You folks that have Dual Processors, Dual Core Processors or Quad Core
 EV> Processors - What kind of things do you do to get both (or all) the CPUs
 EV> to do something for you while you are on the computer?

See above.  Photoshop has multiple CPU capabilities as does DVD Shrink. 
However, most folks don't do that a lot so what you're apt to see is just
smoother system operation since a CPU that's busy doesn't stop the system from
responding.  A note on Intel CPUs, any of the "hyper-threading" CPUs show *two*
CPUs per physical CPU.  That's because there's another "sort-of" CPU built into
the core to help off-load some processing.  It's NOT the same thing as a dual
CPU system, either with 2 CPUs or a dual core CPU - the performance difference
is 20-30% with a hyper-threaded CPU *if the app is compiled for the support*
(otherwise there's the potential for a performance LOSS) while a dual core or
dual CPU system can provide 80-90% performance gain when using a multi-threaded
application or running two applications at the same time (the latter is kinda
fun to do - launch two instances of an app that allows it and process two
separate jobs at the same time with no slowdown in either one).

However, the end result is that most folks won't know the difference. People in
this echo are more likely to do weird things so are more likely to notice... 
;)

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