Very Computer

Can anybody tell me the relative performance of a dual 500 mhz P3 and
a single cpu 1.8 ghz P4, on very disk intensive tasks? I expect the
dual processors will  not be much faster than a single...

I'm guessing the P4 will be 8 times as fast?

Any websites with speed graphs?

Thanks
Jim

p3dp4

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"Ars longa, vita brevis"

Did you pull this off a fortune cookie? The CPU speed doesn't have
much to do with disk intensive stuff, this is primarily a matter of
HDD speed. Besides, the performance difference depends on the kind of
task. If you're running some software that supports SMP the dual 500
can use both CPUs to the maximum.

Now for the main question. I think with non-SMP tasks the P4 will
range at best at around 3x to 3.5x (max), maybe a little more if you
got some software that's P4-optimized and dumb frequency-depended in
its scalability. Doing SMP stuff, the difference drops to something
between 2x and 2.5x.

JK'02

:>Can anybody tell me the relative performance of a dual 500 mhz P3 and
:>a single cpu 1.8 ghz P4, on very disk intensive tasks? I expect the
:>dual processors will  not be much faster than a single...
:>
:>I'm guessing the P4 will be 8 times as fast?

: Did you pull this off a fortune cookie? The CPU speed doesn't have
: much to do with disk intensive stuff, this is primarily a matter of
: HDD speed. Besides, the performance difference depends on the kind of
: task. If you're running some software that supports SMP the dual 500
: can use both CPUs to the maximum.

: Now for the main question. I think with non-SMP tasks the P4 will
: range at best at around 3x to 3.5x (max), maybe a little more if you
: got some software that's P4-optimized and dumb frequency-depended in
: its scalability. Doing SMP stuff, the difference drops to something
: between 2x and 2.5x.

Probably the P4 will run with DDR or Rambus and this has also some speed
impact.  

Bye
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--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------

The cpu will make somewhere between 0 and 0 percent difference in disk
access speed.  The faster disk drives and faster disk interface that would
likely come with any decent modern computer (or can be purchased as an
upgrade for your existing machine) are likely to make a difference though
(maybe 2-3x).

For more "normal"  apps I'd expect a 1.8ghz P4 to be about as fast as a
1.4GHz P3 and as a rule of thumb (very rough obviously) you get about 50%
performance improvement for every 100% increase in MHz within a particular
cpu generation.  So... about 150% average speed improvement for general apps
that don't take advange of SMP.  If you have apps that take advantage of SSE
or SSE2 (only on the P4) then you'll do a lot better.

--
Ray

That's already considered.

JK'02

Empiric Evidence:

I run a dual PII 200 with a RAID5 array with 5 drives, all on separate
IDE100 controller channels.

Watching xosview while doing disk IO I see the CPU max out on one, and
then the other - during writing. I see the same thing during reading.
This means to me that a single faster CPU will work better than 2 CPUs of
half (or worse) MHz. When the system was set up with the same drives as a
RAID0 (striped) the throughput was up, but the CPU was still the limiting
factor since heavy IO maxed it out.

IDE is CPU intensive. Soft RAID is CPU intensive. The more CPU you have,
to the point where the CPU is not 100% engaged when the drives IO
throughput maxes out, the better - and it appears from the above that
this works better with a single fast as opposed to dual slow.

SCSI is far less CPU intensive - so I'd guess that either of your choices
would do.

Note: a dual CPU system with fast enough individual CPU to max the drives
and have some headroom will be more responsive to other processes while
the intensive disk stuff is running IMHO. YMMV ;)

richard

--
Richard C. Pitt                 C.E.O. Belcarra Technologies

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