multitasking smoothness, what's he talking about?

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Archived from groups: comp.sys.ibm.pc.hardware.chips (More info?)

Okay, I realize this guy is just a commentator and I really shouldn't
pay attention to him, but what this guy is talking about seems almost
counter-intuitive. Here's the article:

http://weblog.infoworld.com/yager/2005/06/16.html

Okay, he's commenting about the relative smoothness of multitasking
Apple Macintosh on PPC vs. various x86 chips on Windows. He's saying
that it's very choppy on a single-threaded Pentium-M. Then he says it's
much better, but still a little choppy on dual-core Pentium-D or
dual-processor Xeon processors. He says its extremely smooth on
Hyperthreaded Pentium 4. And then most bafflingly, it's smoother still
on Athlon 64 and Opteron.

Okay assuming that Pentium-M, Athlon 64, Opteron, and even Pentium 4
without Hyperthreading are all single-threaded, then their multitasking
has to be done through the Windows task switcher, and they would all be
in the same boat. So why would Pentium-M be any worse than the others?
Why would Hyperthreading be smoother than dual-core or dual-processor,
when it's supposed to be the bastard child of the various
multithreading technologies? And why would single-threaded Athlon
64/Opteron be smoother than Hyperthreaded P4?

Yousuf Khan

 

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Robert Redelmeier wrote:
> Good questions, all. But my first question is:
> What is this dude calling "smoothness"?
>
> I suspect he is looking a focus-shift time -- the
> time it takes to bring a background window to the foreground.
> Or maybe the "smoothness" of that repaint.
>
> His laptop Pentium-M almost certain sux at this.
> It might even have UMA graphics!

Okay yeah, that would make some sense, if he's using UMA graphics.

> From the order he gives, memory latency seems to
> be the important factor.

With the Athlon 64/Opterons having the built-in memory controllers,
there would be much less latency there than even a big cache
Hyperthreaded Xeon.

Yousuf Khan

 

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YKhan <yjkhan@gmail.com> wrote:
> http://weblog.infoworld.com/yager/2005/06/16.html

> Okay, he's commenting about the relative smoothness
> of multitasking Apple Macintosh on PPC vs. various x86
> chips on Windows. He's saying that it's very choppy on a
> single-threaded Pentium-M. Then he says it's much better, but
> still a little choppy on dual-core Pentium-D or dual-processor
> Xeon processors. He says its extremely smooth on Hyperthreaded
> Pentium 4. And then most bafflingly, it's smoother still on
> Athlon 64 and Opteron.

> Okay assuming that Pentium-M, Athlon 64, Opteron, and even
> Pentium 4 without Hyperthreading are all single-threaded,
> then their multitasking has to be done through the Windows
> task switcher, and they would all be in the same boat. So
> why would Pentium-M be any worse than the others? Why would
> Hyperthreading be smoother than dual-core or dual-processor,
> when it's supposed to be the bastard child of the various
> multithreading technologies? And why would single-threaded
> Athlon 64/Opteron be smoother than Hyperthreaded P4?


Good questions, all. But my first question is:
What is this dude calling "smoothness"?

I suspect he is looking a focus-shift time -- the
time it takes to bring a background window to the foreground.
Or maybe the "smoothness" of that repaint.

His laptop Pentium-M almost certain sux at this.
It might even have UMA graphics!

From the order he gives, memory latency seems to
be the important factor.

-- Robert