4 ms·

Why is intel like this =\

brianwawok 4y ago
The laptop builder likely didn’t spend the extra $2 to properly cool the CPU, so the CPU slows down to prevent burning out or burning your lap? The CPU being smart about its own temp is a good thing.
- wmf 4y ago
  That's not what's happening in this case. Linux is getting much lower performance than Windows on the same laptop due to a firmware bug.
  - mjg59 4y ago
    No, Linux is getting lower performance than Windows because distributions aren't shipping the tooling needed to inform the firmware that the OS can manage platform thermals, and so the firmware is defaulting to a safe state. Of course, the reason they're failing to do so is because Intel never publicly documented any of this.
    - ladyanita22 4y ago
      I don't understand what's so difficult about this. Why is Intel not providing the documentation? And what is it so difficult to reverse engineer? Is this tool correctly reading the DPTF data and correcting for it?
      - mjg59 4y ago
        > I don't understand what's so difficult about this. It requires parsing multiple undocumented binary file formats, making sense of how the information in each is interlinked, and writing code that keeps track of system state, compares it against the firmware policy, and then imposes the appropriate constraints. > Why is Intel not providing the documentation? I have no idea. > And what is it so difficult to reverse engineer? https://github.com/mjg59/thermal_daemon/compare/028bde5bf0f14982cc23382cba41345a3b3e007c..HEAD https://github.com/mjg59/thermal_daemon/compare/028bde5bf0f1... was my initial implementation of this (remember to click "Load diff" for anything that's too large for github to display by default). There's a fair amount of complexity here! > Is this tool correctly reading the DPTF data and correcting for it? Thermald reads the DPTF data, throttled doesn't. I can't promise that thermald reads it correctly given the lack of a spec, but to the best of my knowledge it does.
wmf 4y ago
Why does Intel allow firmware to control power management? That's a long story but it's very boring and hardly evil.
mjg59 4y ago
Manufacturers (rightly or wrongly) believe users want machines that are as thin and light as possible. This makes a bunch of things more complicated, including managing system thermals. Heat generated from the CPU has to go somewhere. As you get thinner, it's hard to get as much airflow and so fans are less effective. As you reduce the amount of material in the chassis, the less heat can be dumped in there without it heating up enough to potentially be uncomfortable for the user. Larger internal batteries become another source of heat while charging. Handling all of this safely becomes difficult, especially because there isn't necessarily a policy that satisfies all your users. But you can't leave it purely up to the OS either, because the OS has no idea of what the thermal characteristics of the platform are. So rather than attempting to encode all of this policy directly into firmware, Intel wrote the Dynamic Power and Thermal Framework (DPTF) spec, providing a mechanism for the firmware to share information about thermal control interfaces, interactions, and desired temperature bounds, and then let the OS make policy control decisions around that. Until the OS indicates it's ready to take over, the firmware imposes a default safe policy that's guaranteed to avoid any thermal issues, albeit at the cost of performance. Of course, this only works if the OS knows how to do this, and Intel never publicly documented it so I had to reverse engineer it instead.
- ladyanita22 4y ago
  Is Linux taking a conservative approach because they're ignoring the DPTF? Why is this not a problem on Windows?
  - mjg59 4y ago
    By default Linux is taking no approach at all, which means the thermal policy is the most conservative the firmware can configure. If you install thermald then Linux will implement the same policy that Windows does and should have the same performance.
- pjmlp 4y ago
  Another example of how being open source friendly boils down to "it depends on the green paper" even for the companies that do market themselves as such. This is not the only area where Intel doesn't really support Linux, some of their GPU models also come to mind, like the PowerVR based ones in the past.
userbinator 4y ago
This isn't Intel's fault... unless you consider them providing things like adjustable power limits a problem. Its CPUs have had automatic thermal throttling and will shutdown on catastrophic overheating ever since the Pentium II. It's all the fault of manufacturers who want to both save cost with inadequate heatsinks and impose arbitrary restrictions on their products. The software in this article looks like the Linux equivalent of ThrottleStop, a Windows application that was the first to expose the truth behind it all.
- mjg59 4y ago
  I'm not sure how failing to publicly document the DPTF specification is anything other than Intel's fault. The CPUs are not running in such a constrained configuration under Windows, for example, because Intel supply drivers to configure them appropriately.
  - userbinator 4y ago
    Windows doesn't need DPTF either --- a quick search online shows just how many others are getting much better performance after applying NoDPTF.reg and similar fixes.
    - mjg59 4y ago
      You're being weirdly obtuse here. Yes, you can make hardware perform faster by running it outside its design limits. That doesn't mean it's a good idea in the general case, even if the tradeoffs make sense for you as an individual.
      - userbinator 4y ago
        "design limits", more like "marketing limits". It's certainly a good idea if you realise just how much they're fleecing you.
  - ladyanita22 4y ago
    Exactly, the CPUs run much more loosely on Windows than on Linux. It shouldn't be too difficult to correct this...
scruple 4y ago
I was very surprised by some of the thermal characteristics of my i7-13700k. My previous build was an i7-4790k, so it's been a minute. I had to undervolt this thing and cap it's max TDP (disable boost modes -- it has boost modes which are very thirsty) to get it to complete benchmarks while staying under 90* C (with a top of the line case, very good fans / circulation, and a large AIO). It's great now but undertuning the thing is a total departure from what I recall from '00s and '10s gaming machines.
- csdvrx 4y ago
  I wish I could undervolt my laptop. As noted by the author: > ===== Notice that undervolt is typically locked from 10th gen onwards! ===== I can't even modify the BIOS due to BootGuard and the keys burned into the CPU. Hopefully there will be a way to leak/extract the keys someday, as this create real e-waste for fake security.
  - mjg59 4y ago
    Boot Guard is based on RSA signatures, so the private key material isn't present on the device
    - csdvrx 4y ago
      I was thinking more about the recent Alder Lake Lenovo leaks :) Right now I'm fighting with nohz_full and rcu_nocbs to limit the wakes per second, with irqaffinity on top to isolate to one core what must happen so that the others can stay in PC8 when I'm not compiling. I'm down to about 350 on a 12th gen Alder Lake with E and P cores running Wayland with a few terminals, Thunderbird and Edge) but I wish I had the ability to also undervolt to go beyond 4W
- NavinF 4y ago
  > i7-13700k 253 W max turbo power is not that crazy by today's standards. > top of the line case, very good fans / circulation, and a large AIO I think you'll find that what people consider good cooling for a desktop has changed somewhat in the last decade. My first GPU didn't even have a fan, but today it's fairly common for enthusiast builds to have an external radiator. I dunno what you consider large, but most AIOs only have slightly more surface area than large air coolers so they really aren't worth it for sustained workloads like gaming or ML training. Custom loops have always been the go-to solution.
moffkalast 4y ago
Consumers: keep buying whatever garbage Intel puts out each year Consumers: "Why would Intel do this?"

The laptop builder likely didn’t spend the extra $2 to properly cool the CPU, so the CPU slows down to prevent burning out or burning your lap? The CPU being smart about its own temp is a good thing.

wmf 4y ago
That's not what's happening in this case. Linux is getting much lower performance than Windows on the same laptop due to a firmware bug.
- mjg59 4y ago
  No, Linux is getting lower performance than Windows because distributions aren't shipping the tooling needed to inform the firmware that the OS can manage platform thermals, and so the firmware is defaulting to a safe state. Of course, the reason they're failing to do so is because Intel never publicly documented any of this.
  - ladyanita22 4y ago
    I don't understand what's so difficult about this. Why is Intel not providing the documentation? And what is it so difficult to reverse engineer? Is this tool correctly reading the DPTF data and correcting for it?
    - mjg59 4y ago
      > I don't understand what's so difficult about this. It requires parsing multiple undocumented binary file formats, making sense of how the information in each is interlinked, and writing code that keeps track of system state, compares it against the firmware policy, and then imposes the appropriate constraints. > Why is Intel not providing the documentation? I have no idea. > And what is it so difficult to reverse engineer? https://github.com/mjg59/thermal_daemon/compare/028bde5bf0f14982cc23382cba41345a3b3e007c..HEAD https://github.com/mjg59/thermal_daemon/compare/028bde5bf0f1... was my initial implementation of this (remember to click "Load diff" for anything that's too large for github to display by default). There's a fair amount of complexity here! > Is this tool correctly reading the DPTF data and correcting for it? Thermald reads the DPTF data, throttled doesn't. I can't promise that thermald reads it correctly given the lack of a spec, but to the best of my knowledge it does.

wmf 4y ago

Why does Intel allow firmware to control power management? That's a long story but it's very boring and hardly evil.

mjg59 4y ago

Manufacturers (rightly or wrongly) believe users want machines that are as thin and light as possible. This makes a bunch of things more complicated, including managing system thermals. Heat generated from the CPU has to go somewhere. As you get thinner, it's hard to get as much airflow and so fans are less effective. As you reduce the amount of material in the chassis, the less heat can be dumped in there without it heating up enough to potentially be uncomfortable for the user. Larger internal batteries become another source of heat while charging. Handling all of this safely becomes difficult, especially because there isn't necessarily a policy that satisfies all your users. But you can't leave it purely up to the OS either, because the OS has no idea of what the thermal characteristics of the platform are. So rather than attempting to encode all of this policy directly into firmware, Intel wrote the Dynamic Power and Thermal Framework (DPTF) spec, providing a mechanism for the firmware to share information about thermal control interfaces, interactions, and desired temperature bounds, and then let the OS make policy control decisions around that. Until the OS indicates it's ready to take over, the firmware imposes a default safe policy that's guaranteed to avoid any thermal issues, albeit at the cost of performance. Of course, this only works if the OS knows how to do this, and Intel never publicly documented it so I had to reverse engineer it instead.

ladyanita22 4y ago
Is Linux taking a conservative approach because they're ignoring the DPTF? Why is this not a problem on Windows?
- mjg59 4y ago
  By default Linux is taking no approach at all, which means the thermal policy is the most conservative the firmware can configure. If you install thermald then Linux will implement the same policy that Windows does and should have the same performance.
pjmlp 4y ago
Another example of how being open source friendly boils down to "it depends on the green paper" even for the companies that do market themselves as such. This is not the only area where Intel doesn't really support Linux, some of their GPU models also come to mind, like the PowerVR based ones in the past.

userbinator 4y ago

This isn't Intel's fault... unless you consider them providing things like adjustable power limits a problem. Its CPUs have had automatic thermal throttling and will shutdown on catastrophic overheating ever since the Pentium II. It's all the fault of manufacturers who want to both save cost with inadequate heatsinks and impose arbitrary restrictions on their products. The software in this article looks like the Linux equivalent of ThrottleStop, a Windows application that was the first to expose the truth behind it all.

mjg59 4y ago
I'm not sure how failing to publicly document the DPTF specification is anything other than Intel's fault. The CPUs are not running in such a constrained configuration under Windows, for example, because Intel supply drivers to configure them appropriately.
- userbinator 4y ago
  Windows doesn't need DPTF either --- a quick search online shows just how many others are getting much better performance after applying NoDPTF.reg and similar fixes.
  - mjg59 4y ago
    You're being weirdly obtuse here. Yes, you can make hardware perform faster by running it outside its design limits. That doesn't mean it's a good idea in the general case, even if the tradeoffs make sense for you as an individual.
    - userbinator 4y ago
      "design limits", more like "marketing limits". It's certainly a good idea if you realise just how much they're fleecing you.
- ladyanita22 4y ago
  Exactly, the CPUs run much more loosely on Windows than on Linux. It shouldn't be too difficult to correct this...

scruple 4y ago

I was very surprised by some of the thermal characteristics of my i7-13700k. My previous build was an i7-4790k, so it's been a minute. I had to undervolt this thing and cap it's max TDP (disable boost modes -- it has boost modes which are very thirsty) to get it to complete benchmarks while staying under 90* C (with a top of the line case, very good fans / circulation, and a large AIO). It's great now but undertuning the thing is a total departure from what I recall from '00s and '10s gaming machines.

csdvrx 4y ago
I wish I could undervolt my laptop. As noted by the author: > ===== Notice that undervolt is typically locked from 10th gen onwards! ===== I can't even modify the BIOS due to BootGuard and the keys burned into the CPU. Hopefully there will be a way to leak/extract the keys someday, as this create real e-waste for fake security.
- mjg59 4y ago
  Boot Guard is based on RSA signatures, so the private key material isn't present on the device
  - csdvrx 4y ago
    I was thinking more about the recent Alder Lake Lenovo leaks :) Right now I'm fighting with nohz_full and rcu_nocbs to limit the wakes per second, with irqaffinity on top to isolate to one core what must happen so that the others can stay in PC8 when I'm not compiling. I'm down to about 350 on a 12th gen Alder Lake with E and P cores running Wayland with a few terminals, Thunderbird and Edge) but I wish I had the ability to also undervolt to go beyond 4W
NavinF 4y ago
> i7-13700k 253 W max turbo power is not that crazy by today's standards. > top of the line case, very good fans / circulation, and a large AIO I think you'll find that what people consider good cooling for a desktop has changed somewhat in the last decade. My first GPU didn't even have a fan, but today it's fairly common for enthusiast builds to have an external radiator. I dunno what you consider large, but most AIOs only have slightly more surface area than large air coolers so they really aren't worth it for sustained workloads like gaming or ML training. Custom loops have always been the go-to solution.

moffkalast 4y ago

Consumers: keep buying whatever garbage Intel puts out each year Consumers: "Why would Intel do this?"