3 ms·

Since Apple have full control over each Mac's hardware, couldn't they within a quite narrow average know how much power is consumed? You also have hardware con

Since Apple have full control over each Mac's hardware, couldn't they within a quite narrow average know how much power is consumed? You also have hardware control chips like the T1/T2 that could help narrow this down even further. I would get it for PC's, but here, it's quite different.

lkxijlewlf 4y ago
Yes. But why would they? There's no benefit for them.
- mattnewton 4y ago
  A lot of reasons to profile this if you want to advertise battery life. Internally it let's you collect metrics on apps threatening your battery life promises and externally it gives the consumers the ability to accurately blame apps when they get lower than expected battery life. For example they can notice that safari uses less power than chrome or that final cut uses way more power than they expected, etc etc
  - lkxijlewlf 4y ago
    They don't want end users to have access to battery life stats. The took that out a few OS X versions ago. They don't people to say, after the last updated I get 1 hour less battery life, WTF?
    - b3morales 4y ago
      Battery stats are available in the Battery System Pref pane and that has not changed. There is also some health information in the System Profiler (Apple Menu/About This Mac/System Report).
jeffbee 4y ago
They wouldn’t need to guess. CPUs measure their own current consumption and demand specific voltage levels from their regulators. They know the instantaneous power consumption to at least three significant digits.
wongarsu 4y ago
On Windows (or Linux) you can get power consumption numbers down to the core using tools like HWMonitor. My CPU is currently using 95W, and my GPU uses 15W. Of course then you have fans, motherboard etc. On server hardware (where software-queriable power meters in the power supply are commonplace) having as much power draw from the fans as from the CPU isn't uncommon.
- cuu508 4y ago
  Where is HWMonitor getting this data from? > My CPU is currently using 95W Are you currently stressing the CPU (compiling, rendering, ...)? If you are not, the 95W figure seems suspect. (FWIW, my entire system, fans and all, uses 25W at the wall when idle. The CPU is Intel 9700k, no dGPU).
  - wongarsu 4y ago
    It's a desktop with a 24 core Threadripper with a 250W TPD, not designed for efficiency at all. Probably something or another was using 2 to 6 cores.
- throwaway09223 4y ago
  > power consumption numbers down to the core using tools like HWMonitor. These are just rough estimates and can be wildly inaccurate (just like in the OSX post we're discussing). AFAIK there's no facility for actual measurement. > On server hardware (where software-queriable power meters in the power supply are commonplace) Are you certain these are actual meters and not just estimates done in software?
  - adrian_b 4y ago
    Any modern computer has facilities for actual measurements. All motherboards contain sensor chips that can measure the voltages of all power supplies that are used on that board. All modern CPUs (i.e. all CPUs with variable clock frequency) have internal sensors that measure the currents and the voltages provided by their power supplies. From the currents and the voltages the power consumption is computed. The current and voltage values, together with the temperatures provided by one or more temperature sensors, are used by the algorithms that control the turbo clock frequencies. (The reason why power consumption values are needed by the turbo algorithms is because the chip temperature has a too large inertia, if the clock frequency would be reduced only after the temperature is already too high it would be too late; using the power consumption the future temperature raise can be predicted and the clock frequency can be reduced in advance, avoiding the overshooting of the maximum temperature.) Some of the values provided by the internal CPU sensors are available in model-specific registers, so the monitoring programs can read them and display the CPU power consumption. The discrete GPUs from NVIDIA and AMD also have internal sensors that can be read by programs to display the GPU power consumption. The GPUs also use their internal sensors to control their clock frequencies. Most inaccuracies in reporting the power consumption are due to poor or non-existent documentation of the sensors, which affects especially the AMD CPUs and some of the motherboard sensors. The Intel sensors are usually well documented. How to read and display the power consumption values provided by the internal CPU sensors can be seen e.g. in the source code of the utility turbostat, which can be found in the source tree of the Linux kernel. (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/power/x86/turbostat/turbostat.c https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin...) Apple should have good internal documentation, which should enable accurate power consumption reporting. They cannot blame an external company which refused to provide adequate documentation for the sensors.
avianlyric 4y ago
They do, and their software knows as well. It’s just Activity Monitor that isn’t currently using the data for some reason.
matheusmoreira 4y ago
Can't the CPU just measure how much power it's drawing?

lkxijlewlf 4y ago

Yes. But why would they? There's no benefit for them.

mattnewton 4y ago
A lot of reasons to profile this if you want to advertise battery life. Internally it let's you collect metrics on apps threatening your battery life promises and externally it gives the consumers the ability to accurately blame apps when they get lower than expected battery life. For example they can notice that safari uses less power than chrome or that final cut uses way more power than they expected, etc etc
- lkxijlewlf 4y ago
  They don't want end users to have access to battery life stats. The took that out a few OS X versions ago. They don't people to say, after the last updated I get 1 hour less battery life, WTF?
  - b3morales 4y ago
    Battery stats are available in the Battery System Pref pane and that has not changed. There is also some health information in the System Profiler (Apple Menu/About This Mac/System Report).

jeffbee 4y ago

They wouldn’t need to guess. CPUs measure their own current consumption and demand specific voltage levels from their regulators. They know the instantaneous power consumption to at least three significant digits.

wongarsu 4y ago

On Windows (or Linux) you can get power consumption numbers down to the core using tools like HWMonitor. My CPU is currently using 95W, and my GPU uses 15W. Of course then you have fans, motherboard etc. On server hardware (where software-queriable power meters in the power supply are commonplace) having as much power draw from the fans as from the CPU isn't uncommon.

cuu508 4y ago
Where is HWMonitor getting this data from? > My CPU is currently using 95W Are you currently stressing the CPU (compiling, rendering, ...)? If you are not, the 95W figure seems suspect. (FWIW, my entire system, fans and all, uses 25W at the wall when idle. The CPU is Intel 9700k, no dGPU).
- wongarsu 4y ago
  It's a desktop with a 24 core Threadripper with a 250W TPD, not designed for efficiency at all. Probably something or another was using 2 to 6 cores.
throwaway09223 4y ago
> power consumption numbers down to the core using tools like HWMonitor. These are just rough estimates and can be wildly inaccurate (just like in the OSX post we're discussing). AFAIK there's no facility for actual measurement. > On server hardware (where software-queriable power meters in the power supply are commonplace) Are you certain these are actual meters and not just estimates done in software?
- adrian_b 4y ago
  Any modern computer has facilities for actual measurements. All motherboards contain sensor chips that can measure the voltages of all power supplies that are used on that board. All modern CPUs (i.e. all CPUs with variable clock frequency) have internal sensors that measure the currents and the voltages provided by their power supplies. From the currents and the voltages the power consumption is computed. The current and voltage values, together with the temperatures provided by one or more temperature sensors, are used by the algorithms that control the turbo clock frequencies. (The reason why power consumption values are needed by the turbo algorithms is because the chip temperature has a too large inertia, if the clock frequency would be reduced only after the temperature is already too high it would be too late; using the power consumption the future temperature raise can be predicted and the clock frequency can be reduced in advance, avoiding the overshooting of the maximum temperature.) Some of the values provided by the internal CPU sensors are available in model-specific registers, so the monitoring programs can read them and display the CPU power consumption. The discrete GPUs from NVIDIA and AMD also have internal sensors that can be read by programs to display the GPU power consumption. The GPUs also use their internal sensors to control their clock frequencies. Most inaccuracies in reporting the power consumption are due to poor or non-existent documentation of the sensors, which affects especially the AMD CPUs and some of the motherboard sensors. The Intel sensors are usually well documented. How to read and display the power consumption values provided by the internal CPU sensors can be seen e.g. in the source code of the utility turbostat, which can be found in the source tree of the Linux kernel. (https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/power/x86/turbostat/turbostat.c https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin...) Apple should have good internal documentation, which should enable accurate power consumption reporting. They cannot blame an external company which refused to provide adequate documentation for the sensors.

avianlyric 4y ago

They do, and their software knows as well. It’s just Activity Monitor that isn’t currently using the data for some reason.

matheusmoreira 4y ago

Can't the CPU just measure how much power it's drawing?