VOGONS


First post, by clueless1

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So in the process of trying to gather results from 486 and faster systems with caches disabled, I've been playing a lot with gerwin's Setmul utility.

What a neat tool! I finally took the time to dive a little deeper in the documentation (just reading setmul /? gives a world of info) and realized that there are a ton of switches available to Pentium owners. So I decided to try to test every combination of switches I could with my Pentium Overdrive 200. 😉

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Even on a Pentium, there is way more to this utility than just disabling L1 cache. I was able to get down almost to an Am386SX40; I equaled an Am386DX40; and I got close to an i486SX25.

Not to mention all the other features for owners of many other types of processors. Thank you, gerwin!

The more I learn, the more I realize how much I don't know.
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Reply 1 of 27, by PhilsComputerLab

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Nice!

I'll have to check that out. Does this also work with the standard Pentium and MMX?

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Reply 2 of 27, by clueless1

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I've only tried with the POD so far, but I don't see why not.

From setmul docs:

-Pentium P54C test register "TR12" options. Parameters: BPD - Disable Branch Prediction VPD - Disable V Pipeline L1DX - Disable […]
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-Pentium P54C test register "TR12" options. Parameters:
BPD - Disable Branch Prediction
VPD - Disable V Pipeline
L1DX - Disable L1 cache exclusively
CCD - Disable L1 code cache
DCD - Disable L1 data cache
PFE - Pentium Features Enable; Resets the above TR12 options to default.

The more I learn, the more I realize how much I don't know.
OPL3 FM vs. Roland MT-32 vs. General MIDI DOS Game Comparison
Let's benchmark our systems with cache disabled
DOS PCI Graphics Card Benchmarks

Reply 3 of 27, by gerwin

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Nice to see these Pentium options of SetMul put to good use!
Originally I tested it on a Gold-Capped Pentium 90MHz (P54C): All worked fine. After that I also tried it with one of my Pentium MMX processors, 200 or 233MHz (P55C): The TR12 switches no longer had any effect, as if intel removed these registers... So I am surprised to see it work on the POD 200. POD 200 being an MMX model AFAIK.

Edit: correction - The TR12 settings actually do slow down all six different Pentium MMX processors I have here. i just tested that properly. So AFAIK it just works with any Socket 7 Pentium.
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Last edited by gerwin on 2017-09-14, 15:10. Edited 2 times in total.

--> ISA Soundcard Overview // Doom MBF 2.04 // SetMul

Reply 4 of 27, by ibm5155

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I wish I could disable the motherboard cache by software 🙁 (even if the restart is kinda fast)
one question, If I set setmul for 500MHz on ms-dos (400 original), and I restart and boot into Windows xp, it's goint to stay at 500MHz or 400MHz?

Reply 5 of 27, by clueless1

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ibm5155 wrote:

I wish I could disable the motherboard cache by software 🙁 (even if the restart is kinda fast)
one question, If I set setmul for 500MHz on ms-dos (400 original), and I restart and boot into Windows xp, it's goint to stay at 500MHz or 400MHz?

Setmul commands only live during the session they are started, so they would not survive a reboot. I believe the docs say it is not compatible with XP (among other more modern OSes).

The more I learn, the more I realize how much I don't know.
OPL3 FM vs. Roland MT-32 vs. General MIDI DOS Game Comparison
Let's benchmark our systems with cache disabled
DOS PCI Graphics Card Benchmarks

Reply 6 of 27, by PhilsComputerLab

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A real shame it doesn't work on the MMX. That CPU is just a little bit too fast without caches and could benefit from some further slowing down 🙁

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Reply 7 of 27, by clueless1

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I feel pretty lucky then that it works on my Pentium Overdrive MMX.

The more I learn, the more I realize how much I don't know.
OPL3 FM vs. Roland MT-32 vs. General MIDI DOS Game Comparison
Let's benchmark our systems with cache disabled
DOS PCI Graphics Card Benchmarks

Reply 8 of 27, by gerwin

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Guess the situation is that somewhere along the production of the Pentium MMX they dropped the Test Registers, and it may be interesting to try out some older MMX models to see if they still support the Test Registers.

--> ISA Soundcard Overview // Doom MBF 2.04 // SetMul

Reply 9 of 27, by clueless1

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gerwin wrote:

Nice to see these Pentium options of SetMul put to good use!
Originally I tested it on a Gold-Capped Pentium 90MHz (P54C): All worked fine. After that I also tried it with one of my Pentium MMX processors, 200 or 233MHz (P55C): The TR12 switches no longer had any effect, as if intel removed these registers... So I am surprised to see it work on the POD 200. POD 200 being an MMX model AFAIK.
.

Your P90 is a bit faster than mine (8.97) with L1D. If not too much trouble, would you mind adding your results to my compilation?
https://docs.google.com/spreadsheets/d/1fBPxW … #gid=1443406194

Thanks.

The more I learn, the more I realize how much I don't know.
OPL3 FM vs. Roland MT-32 vs. General MIDI DOS Game Comparison
Let's benchmark our systems with cache disabled
DOS PCI Graphics Card Benchmarks

Reply 10 of 27, by PhilsComputerLab

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Just a tip, between motherboards, memory configurations and BIOS settings there can be quite some variation.

For example I used 16 MB memory (SDRAM) for better compatibility, but that memory was actually EDO and it slowed things down a bit. Memory timings in the BIOS can also have an impact.

So I wouldn't worry too much about a spread in results using the same CPU.

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Reply 11 of 27, by clueless1

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Thanks, Phil. I think it's cool that different platforms can show different characteristics. It says something about the ALI Aladdin V and SDRAM.

The more I learn, the more I realize how much I don't know.
OPL3 FM vs. Roland MT-32 vs. General MIDI DOS Game Comparison
Let's benchmark our systems with cache disabled
DOS PCI Graphics Card Benchmarks

Reply 12 of 27, by PhilsComputerLab

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Yup.

Your thread brings back good memories.

I looked up some old posts of mine from 2010 when I did my own cache experiments and benchmarks. I actually started off with a Slot 1 system, but quickly found that socket 7 is the way to go.

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Reply 13 of 27, by clueless1

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You definitely paved the way for my inspiration. 😀 Thank you!

The more I learn, the more I realize how much I don't know.
OPL3 FM vs. Roland MT-32 vs. General MIDI DOS Game Comparison
Let's benchmark our systems with cache disabled
DOS PCI Graphics Card Benchmarks

Reply 14 of 27, by clueless1

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Here are all the combinations of setmul switches and how they effect performance on my POD 200MMX:

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The more I learn, the more I realize how much I don't know.
OPL3 FM vs. Roland MT-32 vs. General MIDI DOS Game Comparison
Let's benchmark our systems with cache disabled
DOS PCI Graphics Card Benchmarks

Reply 15 of 27, by Tetrium

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I'm wondering a bit here, but could such a program possibly be able to enable the motherboard cache in a s7 rig which is running a Tillamook?

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Reply 16 of 27, by clueless1

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Sadly, in retesting my Pentium 120 cpu with the test registers, I found DCD and CCD (data and code cache) have no effect. These two switches are what allow my POD 200MMX to get into 486 levels of performance. VPD and BPD do work, which allow smaller performance drops into P90 and P100 ranges, and disabling L1 gets me down to Am386SX-40. I'm pretty stoked that the POD supports all these TRs, it makes it a very flexible CPU, from 386DX-25->386DX-33->486-16->486-20->486-25->P120->P133->P166->P200.

The more I learn, the more I realize how much I don't know.
OPL3 FM vs. Roland MT-32 vs. General MIDI DOS Game Comparison
Let's benchmark our systems with cache disabled
DOS PCI Graphics Card Benchmarks

Reply 17 of 27, by Tetrium

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clueless1 wrote:

Sadly, in retesting my Pentium 120 cpu with the test registers, I found DCD and CCD (data and code cache) have no effect. These two switches are what allow my POD 200MMX to get into 486 levels of performance. VPD and BPD do work, which allow smaller performance drops into P90 and P100 ranges, and disabling L1 gets me down to Am386SX-40. I'm pretty stoked that the POD supports all these TRs, it makes it a very flexible CPU, from 386DX-25->386DX-33->486-16->486-20->486-25->P120->P133->P166->P200.

This might actually be an interesting find. Better go start hoarding those 200MHz MMX Overdrives real quick before this gets verified by the masses 😜.

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Interesting Vogons threads (links to Vogonswiki)
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Reply 19 of 27, by BreakPoint

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How on earth P200 may degradate to 386-25???

I wonder if 386-25 system from your test have L2 cache or not.

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