Dual CPUs: worth it??
 

I'm looking at getting a system with dual 200 MHz Pentium pro CPUs

I've been told that to take advantage of dual CPUs you need software specifically written to get maximum performance

If I enable SMP and do a custom kernel compile, will all apps and what-not behave faster, as if 400 MHz sort of???

What are the traps/pros/cons of dual CPU systems?


Forrest.


PS the system I'm looking at has:
dual Pentium pro 200 CPUs
512 MB ram
3 x 9GB SCSI hdds
no screen
for $75 NZD

Reckon it's a good buy?
Hopefully it will run KDE 3.4 pretty well if I get it....

For $75, do it just to play with SMP, SCSI and different raid arrays. I don't know what type of performance you want from a couple 200MHz processors, but the learning experience is probably well worth the $75

Are pentium pro's good CPUs?

Are they faster than standard pentiums at the same clock speed??

The Pentium Pro was Intel's high performance line before the Pentium II came along. The Pentium II is basically a Pentium Pro with MMX support.

I used a PPro200/192MB as my primary server until recently and it performed very well. Nice CPU's, and they don't run very hot (I only had a heatsink on mine with the PSU fan in the proximity moving the air).


Håkan

PPros are AFAIK somewhat like yesterday's version of Xeon's - they have more cache, meaning they should have a bit more oomph. But hey, you don't buy this thing to get an everyday working tool - it's for playing with, right?

My guess at what you can expect:

2x200MHz PPro = 500 MHz Pentium (raw)
Deduct 10% overhead for administering the dual brains = 50MHz
Net result 450MHz Pentium.

But only for SMP-enabled apps, of which i think there's very few. Eg. astronomy-image-processing and medical/molecular-analysis software.

I'd like to know more about the amount of SMP-enabled software available out there. Anyone?

//mA

Runs cool?

Hopefully it'll overclock a bit... ;-D

Forrest

some of this is rehash but this is my experience:

I too had a dual PPro200 system. I ran mine up to 240 before they became unstable, they ran flawlessly with a big case fan and just heatsinks at 235MHz. Your milage may vary

With two CPUs in Linux, the "software written to get max performance" is the SMP kernel, all of the kernel stuff will share CPU power. Even with non-threaded apps running, it's still faster because one CPU will run the app and the other will run the kernel and I/O (OK, so it's a bit more complex than that.) Meaty CPU intensive tasks such as compiles will use both CPUs anyhow because they fork seperate processes and the kernel will distribute those processes between the CPUs even if they aren't (I belive gcc is anyhow) threaded. Many apps like apache also fork processes to do their work, these all get distributed among the CPUs. I would run ktop on mine sometimes and usually when CPU0 went up in utilization, CPU1 would also.

Your average pair of PPro 200s will also have more L1 cache than a typical P400 so that adds a performance edge as well. I usually think of it as just adding the speeds so 2x200 I compare to a 400 but it is faster because the PPro is like today's xeons compared to a P400, K400 or celeron400. One of the big performance boosts will come in the amount and speed of RAM you can stuff onto the board, I had 192MB of 50ns RAM which made a huge difference from the 128MB of 60ns RAM it had before.

Fast I/O systems will make a difference as well. If it has onboard SCSI it's probably an 80 SCSI-3 that you can throw a 10kRPM drive (hopefully those 9gigs are 10k SCSI-3's) on, which is probably on par with today's zippy IDE drives (7.2KRPM 8-16MB cache DMA100/133) and either of these will make a difference over an older IDE drive from the era (typically 5.4KRPM or slower with 1/4M to 2M cache.)

Cool

I bought the system last night and am going to pick it up tomorrow.

I think it's got RAID, so I may be able to do RAID 0 and get a big performance boost


Anyway whats linux like with RAID?


Cheers
Forrest

Although not _exactly_ what the topic of the thread is...

I'm thinking of building either a dual- or quad-server (Opteron, Xeon, or Itanium I have not decided yet) and I plan on using Slackware with it. Will I have to do a lot of configuring to make Linux detect the multiple processors, or should it detect them 'out of the box,' so to speak?

You'll probably have to select a SMP-enabled kernel (near the end of the installation process)

You could always do a custom kernel compile


Cheers
Forrest.

Are pentium pro CPUs i586 or i686?


Forrest.

PS the machine I bought is a "HP Netserver LH Pro"
PPS if you ever get board go to http://www.backyardmetalcasting.com/ it's awesome!

-Slack comes with pre-built kernels for SMP, you can even boot the installer with one if you look up what it's called first. The pre-built SMP kernel supports up to, I belive, 4 procs but it's just a matter of a kernel recompile with a change to the option with a name like, "number of processors." Linix 'gets' SMP, when it's turned on in the kernel, so there are no detection issues aside from SMP support being turned on.

-I'm pretty sure PPros are technically still i586, I compiled everything for my PPro box as i586 and that's prolly cause I read somewhere that they were not i686.

-I haven't played with Linux and RAID, except for basic software RAID, so I can't really answer any questions about it, except that it probably works.

"uname -a" reports them as i686s

For some reason when I start the server, the 3 SCSI hard drives don't "spin up", so you can't boot off them.
The only way I can boot off the SCSI drive is to boot of a linux installation CD, which detects and "spins up" the SCSI drives
Then I reboot, and the drives are still spinning, and I can boot off them!

Any idea how to make the BIOS spin them up??

Cheers
Forrest

During BIOS Post there should be a spot where the onboard SCSI also shows it's POST messages. At this point, at least for most Adaptec although others are usually the same, you can press CTRL-A to get into the SCSI system's config and either reset to defaults or turn on device start.

ok i'll try that

I fixed the problem by removing some jumpers off the drives :-)



Forrest