Author Topic: Multi core CPUs - how many are running > 4?  (Read 332 times)

Dariusz Piatkowski

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Multi core CPUs - how many are running > 4?
« on: November 20, 2020, 08:28:38 pm »
Alright...how many of your are running CPUs with more than 4 or 5 cores?

I ask b/c with the newer motherboard I can finally boot up with with the full 6 cores enabled on my AMD Phenom II X6 1100T CPU . This is with AOS ACPI 3.23.15 drivers.

The old motherboard would TRAP each time I attempted to do so.

However, my CPU monitors show on-going CPU spikes and I cannot for the life of me figure out where this is coming from. Basically, the ACPI Power Manager is disabled, which means the cores are running "all-out", no throttling back, etc...which is fine as this is my desktop box and running 24x7.

Therefore, if the ACPI PM is not active, than the only reason for CPUs to be spiking is either the ACPI driver itself, or something in the kernel???

So I'm curious if anyone else is seeing this?


Dave Yeo

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Re: Multi core CPUs - how many are running > 4?
« Reply #1 on: November 21, 2020, 12:12:01 am »
Does it go away if you disable a core or 2? Does changing any BIOS options such as "cool and quiet" help?

Dariusz Piatkowski

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Re: Multi core CPUs - how many are running > 4?
« Reply #2 on: November 21, 2020, 03:10:25 am »
Hey Dave!

Does it go away if you disable a core or 2?

Yup...indeed it does! I can either disable a core in BIOS, or boot with /MAXCPU=5 setting and either one works to product a stable non-spiked CPU behaviour.

This is what has made me think that the ACPI driver has an "issue" with the 6-core setup. Please note, when I say "issue" I do mean with my hardware combo. Now, if others pipe in and we see a trend, well, that'd be something different, which is part of the reason why I'm posing this question.

...Does changing any BIOS options such as "cool and quiet" help?...

I toyed around with numerous BIOS options in the past. For the most part I have all of these disabled because I find the ACPI PM scheduler NOT to work effectively, nor efficiently to start off with. Quite some time ago I shut off the ACPI PM and simply let the machinery run as it may, meaning: pedal to the metal, it's a full boost speed across all the cores. On my Phenom that means 4G when in 5 core mode and about 3.8G when in 6 core. Through experiments I found a single core that wasn't quite as tollerant of too large a boost, so I shut that core off in BIOS if I intend to run at the 4G speed. That used to be my default mode since the 6 core boot was a hit-n-miss, and eventually as ACPI drivers changed it actually caused a consistent TRAP, so I eventually gave up on it altogether.

Now that I am in the 6-core mode by default I may go back to re-test, but I suspect the previous brick-wall was really a CPU core specific hardware limit, and that's not going to be overcome by a different motherboard.

Dariusz Piatkowski

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Re: Multi core CPUs - how many are running > 4?
« Reply #3 on: November 21, 2020, 05:34:46 am »
FOUND IT!!!

So as embarrasing as it might feel, because I'm sure I've done this numerous times before - taking the system down to just the bare essentials (core OS/2 stuff with very little, if any utilities, etc. running), I re-did this process one more time.

The difference now I suppose is the fact that I have a reliable 6-core setup. Well, eventually I pegged this down to the PUMonitor utility. This little handy thing has got it all as far as monitoring CPU/tcpip/memory resources, etc...but when core-count here goes past 5...well, that's where the spikes start.

Throttling the system down to a single core, which was then consistently showing 50% usage allowed me to track this down. Good news is that the author open sourced the project sometime back, so I will review to see if I can actually build it and troubleshoot next!!!

Yey, but win here...finally this puts away one of those nuisance type of things and puts my mind at ease knowing that it's not something "off" with a core system component like ACPI.

Dave Yeo

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Re: Multi core CPUs - how many are running > 4?
« Reply #4 on: November 21, 2020, 06:23:50 am »
Good to hear, and makes sense that a CPU monitor might have a flaw with too many CPU's. Wonder if it is obvious what the problem is? Some of these SMP issues are hard to track down.
For myself, running 4 cores for quite a while, I'm quite happy with how ACPI handles them, especially the recent builds where it will shutdown 1,2 or 3 depending on load, and when I have had problems, after David accepted that the problem has existed (by default he figures things are correct, human nature), a fix has happened very quick.
Also happy with the default Xcentre CPU monitor. I've tested PUMonitor a few times but never liked it enough to keep using it.

Dariusz Piatkowski

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Re: Multi core CPUs - how many are running > 4?
« Reply #5 on: November 23, 2020, 10:40:21 pm »
Dave!

Good to hear, and makes sense that a CPU monitor might have a flaw with too many CPU's. Wonder if it is obvious what the problem is? Some of these SMP issues are hard to track down...

Alright, so I spent a little time digging through this code. I have to admit, it's taking a bit longer to digest...ha ha...but I'm getting there.

Found a couple of spots where an assumption is made and code written in a way that supports up to 4 processors. And yet the program init logic relies on DosQuerySysInfo call to get a count of CPUs present. So, given the age of the software (1998) I'm thinking it was quite possible to assume that an end-user OS/2 machine would not sport more than 4 CPUs...yeah?

Right now I'm working through the attempt to re-compile using VAC 3.6.5. If that succeeds I'll see if I can fix up what I think is missing.

Sigurd Fastenrath

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Re: Multi core CPUs - how many are running > 4?
« Reply #6 on: November 23, 2020, 11:28:09 pm »
The T480 run with 4 Cores and 4 Threads very stable, CPU monitor showing 8 cores. ACPI quickly shuts down 7 from Version 3.14 on. Once needed it reenables as much as needed and shuts/throttle them down again once no more power is needed. Worked like a charm.