4 ms·

Do you have a similar concern for all multithreaded programs?

taeric 9y ago
In general, yes. That my computer can do many things is something I take advantage of as a user. The programs should use them to their advantage, but by and large, most programs do not need all of the processing capabilities of my computer, so I expect they should play well together. (Indeed, it takes effort to get the GPU of my computer to help out with anything.)
- rhencke 9y ago
  This is the job of your operating system's scheduler - to divide the limited resource of your computer's CPU time among different competing tasks. In the modern era, a program cannot take more than its fair share of CPU time - otherwise, a runaway program could easily render your computer nearly unusable. (Linux, macOS and Windows all use preemptive multitasking.) The way to tell your operating system what you desire prioritized is, on *nix systems, 'nice'.
  - taeric 9y ago
    I'm well aware of that. I also know that, in general, having to schedule things slows them down. If everything I'm running is trying to schedule something on my entire machine, it is giving my OS more work. Which will, by necessity, be harder to schedule and slow things down. I'm not necessarily against all of this, but I'm also not eagerly embracing more crap to slow down my machine for no apparent reason.
    - demarq 9y ago
      You are assuming that your OS scheduler is nearly at capacity, it isn't. And moreover your CPU is will spend most of it's life idle. I could almost guarantee you this is not the bottleneck of any modern setup.
      - taeric 9y ago
        I can guarantee you that I have jumped over to my browser when doing a compile that is definitely limited by my machine. I'm ok doing this knowing that I will only take up so much work on my machine. I do not go off and kick off another giant compile at the same time. Now, if the browser becomes more and more consuming, hitting my browser could get closer and closer to kicking off another giant compile.
- tedmielczarek 9y ago
  Keep in mind that by parallelizing work the browser can finish the work it's doing faster, which means your CPU can spend more time idle, which is better for power consumption.
  - taeric 9y ago
    That is a big "ostensibly" there. Hard data showing this would be somewhat nice. And, as others, you are also assuming I was not pegging out my machine doing something by choice.
    - lkbm 9y ago
      Metajack mention power usage with parallelization briefly here[0], but doesn't provide the data. [0] https://youtu.be/7q9vIMXSTzc?t=35m https://youtu.be/7q9vIMXSTzc?t=35m (2015)
      - taeric 9y ago
        To be clear, the reasoning is sound on this argument. I'm skeptical due to it never having delivered data, though. :( I want it to be true. I expect that someone should be able to show this with data. I've never seen it done, though.
        noch 9y ago
        You can collect much of this data for yourself on a GNU Linux system by using the cgroups feature of the Linux kernel which is more powerful than nice https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.t... . Using the various CPU* options, you can turn on CPUAccounting, pin a given process and its children/threads to a range of CPUs, place CPUQuotas and so forth. There's a lot of power and granularity there. I know, anecdotally, that devops/sysadmin folk use this to also audit and test energy consumption of processes over time. (Certain popular PID 1 programs have a run tool that allows you to easily, dynamically change and audit process resource usage.) My typical use case, for instance, is auditing and managing various Emacs' processes lifetimes while running potentially racy elisp code.

In general, yes. That my computer can do many things is something I take advantage of as a user. The programs should use them to their advantage, but by and large, most programs do not need all of the processing capabilities of my computer, so I expect they should play well together. (Indeed, it takes effort to get the GPU of my computer to help out with anything.)

rhencke 9y ago
This is the job of your operating system's scheduler - to divide the limited resource of your computer's CPU time among different competing tasks. In the modern era, a program cannot take more than its fair share of CPU time - otherwise, a runaway program could easily render your computer nearly unusable. (Linux, macOS and Windows all use preemptive multitasking.) The way to tell your operating system what you desire prioritized is, on *nix systems, 'nice'.
- taeric 9y ago
  I'm well aware of that. I also know that, in general, having to schedule things slows them down. If everything I'm running is trying to schedule something on my entire machine, it is giving my OS more work. Which will, by necessity, be harder to schedule and slow things down. I'm not necessarily against all of this, but I'm also not eagerly embracing more crap to slow down my machine for no apparent reason.
  - demarq 9y ago
    You are assuming that your OS scheduler is nearly at capacity, it isn't. And moreover your CPU is will spend most of it's life idle. I could almost guarantee you this is not the bottleneck of any modern setup.
    - taeric 9y ago
      I can guarantee you that I have jumped over to my browser when doing a compile that is definitely limited by my machine. I'm ok doing this knowing that I will only take up so much work on my machine. I do not go off and kick off another giant compile at the same time. Now, if the browser becomes more and more consuming, hitting my browser could get closer and closer to kicking off another giant compile.
tedmielczarek 9y ago
Keep in mind that by parallelizing work the browser can finish the work it's doing faster, which means your CPU can spend more time idle, which is better for power consumption.
- taeric 9y ago
  That is a big "ostensibly" there. Hard data showing this would be somewhat nice. And, as others, you are also assuming I was not pegging out my machine doing something by choice.
  - lkbm 9y ago
    Metajack mention power usage with parallelization briefly here[0], but doesn't provide the data. [0] https://youtu.be/7q9vIMXSTzc?t=35m https://youtu.be/7q9vIMXSTzc?t=35m (2015)
    - taeric 9y ago
      To be clear, the reasoning is sound on this argument. I'm skeptical due to it never having delivered data, though. :( I want it to be true. I expect that someone should be able to show this with data. I've never seen it done, though.
      - noch 9y ago
        You can collect much of this data for yourself on a GNU Linux system by using the cgroups feature of the Linux kernel which is more powerful than nice https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.t... . Using the various CPU* options, you can turn on CPUAccounting, pin a given process and its children/threads to a range of CPUs, place CPUQuotas and so forth. There's a lot of power and granularity there. I know, anecdotally, that devops/sysadmin folk use this to also audit and test energy consumption of processes over time. (Certain popular PID 1 programs have a run tool that allows you to easily, dynamically change and audit process resource usage.) My typical use case, for instance, is auditing and managing various Emacs' processes lifetimes while running potentially racy elisp code.