System Slowdown After Playing Games

[hyottositara]

I double-checked the BIOS. I have the latest version, which for this laptop is 1.25.
The CPU Power Management BIOS setting didn't solve the issue.

Here are results after, with CPU Power Management at the default enabled setting. Note that before, the first was the same, but the second was all 20s:

sudo rdmsr --bitfield 15:8 -d -a 0x199
42
42
42
42
42
42
42
42
sudo rdmsr --bitfield 15:8 -d -a 0x198
4
4
4
4
4
4
4
4

[Doug S]

O.K., so the maximum turbo pstate is being asked for, but a pathetic pstate is being given. This appears to be due to the MSRs we have been looking at.
The plan, if your are willing.

Step 1, confirm that I have figured out the correct MSR, i.e. 610h (it isn't necessarily the same address on all processors). Do (the example is my processor):

sudo rdmsr 0x610
800087f8001487f8

and compare to the relevant line from the turbostat output:

cpu0: MSR_PKG_POWER_LIMIT: 0x800087f8001487f8 (locked)

Step 2, to be done after the slowdown situation (but don't play any games anymore), where your MSR reads as "0x43816000dd8001". Do:

sudo wrmsr 0x610 0x42016000dc0160

check it with a subsequent rdmsr, and then check it with turbostat, you should get:

cpu0: MSR_PKG_POWER_LIMIT: 0x42016000dc0160 (UNlocked)
cpu0: PKG Limit #1: DISabled (44.000000 Watts, 28.000000 sec, clamp DISabled)
cpu0: PKG Limit #2: DISabled (44.000000 Watts, 0.002441* sec, clamp DISabled)

Step 3, will be to LOCK the register, but lets wait on that until the results from the above are known.

[hyottositara]

Step 1:

sudo rdmsr 0x610
42016000dc8160

sudo turbostat
...
cpu0: MSR_PKG_POWER_LIMIT: 0x42016000dc8160 (UNlocked)
...

The same.

Step 2:

sudo wrmsr 0x610 0x42016000dc0160
sudo rdmsr 0x610 42016000dc8160
sudo turbostat
...
cpu0: MSR_PKG_POWER_LIMIT: 0x42016000dc8160 (UNlocked)
cpu0: PKG Limit #1: ENabled (44.000000 Watts, 28.000000 sec, clamp DISabled)
cpu0: PKG Limit #2: DISabled (44.000000 Watts, 0.002441* sec, clamp DISabled)

So it changed, although the "disable" bit wasn't accepted, I guess? By the way, I'm able to write this message and use my computer relatively painlessly. Of course I didn't try running a game or anything like that after modifying the MSRs, but I can do things like write this response to you and restart the PC with normal performance.

[andre802]

You have to reduce the number of "Startup Applications"


To do this:
Open up the Dash and type in "startup"
Remove few applications

[Doug S]

O.K., lets try to "lock" the register (after this step, you will need to re-boot to be able to revert the register). So step 2 again, but change the command to this:

sudo wrmsr 0x610 0x8042016000dc0160

[hyottositara]

Looks like that did, indeed, lock the register. I know there are some MSR tracing tools in the kernel, would it be possible to use those to track down what's changing it and causing the slowdown?:

cpu0: MSR_PKG_POWER_LIMIT: 0x8042016000dc8160 (locked)
cpu0: PKG Limit #1: ENabled (44.000000 Watts, 28.000000 sec, clamp DISabled)
cpu0: PKG Limit #2: DISabled (44.000000 Watts, 0.002441* sec, clamp DISabled)

Should I test with the MSR locked and see what happens?

[mercyroy]

i think you have to reduce your memory space and refresh frequently.

[Doug S]

Looks like that did, indeed, lock the register. I know there are some MSR tracing tools in the kernel, would it be possible to use those to track down what's changing it and causing the slowdown?:

cpu0: MSR_PKG_POWER_LIMIT: 0x8042016000dc8160 (locked)
cpu0: PKG Limit #1: ENabled (44.000000 Watts, 28.000000 sec, clamp DISabled)
cpu0: PKG Limit #2: DISabled (44.000000 Watts, 0.002441* sec, clamp DISabled)

Should I test with the MSR locked and see what happens?

Yes, sure. There is still the thermal last line of defense if there is a problem. Myself, I would do a controlled experiment, ramping up CPU use and watch processor package power and temperature.

that being said, while the lock is working, it isn't locking to the desired contents, where package limit 1 is disabled. I'll re-check my decoding of the MSR.

I am not familiar with the MSR tracing tools in the kernel. I am familiar with, and use, trace under a few situations.

Note: I do not understand the other replies on this thread.

EDIT: As far as I can determine, my decoding of the MSR is correct. I do not know why we can not disable the package power limit #1, or in other words clear bit 15 of the register via writing 0x8042016000dc0160

[hyottositara]

Hmm, OK. Well, this does seem to fix the problem after a fashion, in that the system doesn't seem to slow down if I invoke "sudo wrmsr 0x610 0x8042016000dc0160"

I think the root of the issue is whatever is setting this power limit, perhaps I'll try to open a Launchpad bug about it.

I don't understand enough about the power limit MSR to understand why you're trying to completely disable it, it seems like this is something that should always be enabled as a safety feature?

Thanks again for all your help!

[Doug S]

I don't understand enough about the power limit MSR to understand why you're trying to completely disable it, it seems like this is something that should always be enabled as a safety feature?

You still have the thermal limit as a safety feature. For my processor this stuff is disabled.

Anyway, consider that what we did was just a test to prove that we had identified the correct culprit. Yes, it would be good to identify what is actually setting the ridiculous values in that MSR. My best guess is BIOS.

Let us know if you find out anything more. I am very interested in this.

EDIT: Some stuff I found:
https://www.reddit.com/r/thinkpad/co...25_throttling/
https://forums.lenovo.com/t5/ThinkPa...e/td-p/4148955
https://forums.lenovo.com/t5/Lenovo-...u/td-p/4029610