4 ms·

I can't pretend to know enough about the actual implications of this, but I have to wonder - if the goal is to encourage contributors, why not grease the wheels

I can't pretend to know enough about the actual implications of this, but I have to wonder - if the goal is to encourage contributors, why not grease the wheels further on fedpkg/mock? Why must we all have even slower performance? This is more of an aside - I love Fedora, but it already stands out of the pack as a bit slower than others. It's not particularly difficult to rebuild things as-is, is my point - I suppose. It all feels so self-fulfilling. People will want to profile (and benefit from this more)... because things that are context-switch heavy may have slowed down considerably. I'm considering how I may batch my own rebuilds to remove this option with these utilities, mainly to see apples-to-apples what the difference is I know they've published hand-wavy numbers/benchmarks, but I don't trust them for a multitude of reasons

pxc 4y ago
Some thorough benchmarks are something I'd love to read about here on HN. If you ever do those benchmarks, post 'em.
- bravetraveler 4y ago
  I'll be happy to share! I'll probably be waiting for the next release so I can get their pointer-enabled builds. However they do that may give me helpful hints RE: rebuilding the same sources without it. I know the tools to do it, but what I'm imagining right now is a bit convoluted. I'm open to suggestions on things to test. I want to avoid too much reliance on synthetics -- and my 'real world' differs like all of ours My original post has (currently) been down-struck a bit but you're the only reply. I appreciate you taking the time to engage I understand it seems dismissive, perhaps even aggressive, but the Fedora/SuSE people tend to set trends. I just want to measure them. The snark is me finding it ironic that I can (relatively easily) measure this with the same methods they want to avoid... rebuilds with the right options under mock / fedpkg subtext: not that many people find profiling interesting or important... but they will if you start messing with their performance. I find it interesting though so I'm not mad, I just fairly called it self-fulfilling -- I'm going to be profiling because the minority who regularly do, don't want to rebuild (like I will be)
- evmar 4y ago
  https://docs.kernel.org/x86/orc-unwinder.html https://docs.kernel.org/x86/orc-unwinder.html (which I found when looking up ORC, as mentioned in this thread) has some stats for the Linux kernel on the cost of frame pointers: "5-10%" and "3.49% more cache misses with framepointer enabled and 6.59% more cycles". Between this, the various sorts of C language safety checks compilers have been slowly adding, and all the spectre-related defenses, it really does feel like performance is getting slowly consumed by a series of single-digit percentage tweaks.
  - mepian 4y ago
    It's just the time to pay the piper finally arriving, the computer industry ignored security in favor of performance for far too long.
    - nullc 4y ago
      > the computer industry ignored security in favor of performance for far too long Doesn't including an explicit, predictable, frame pointer make life moderately easier for shell code?
  - bravetraveler 4y ago
    I agree -- it's easy to think that a few percent here/there don't hurt, but there's no global context on this. Team A takes away ~4% here, B goes on to do ~3%, and so on and so forth. In only five of these, and consider the chains of Pythonic imports you've seen for example, you've lost roughly a quarter of your performance. (grant me an additive/compounding? nature) This is assuming that the measurements taken in a vacuum even hold up to reality. I've seen reports for misc. other things in the 20% range, so my confidence is remarkably low. I'm not against making it easier, but I don't think everyone always need to be ready for profiling. Making opting in easier lets us ignore the hand-wavy numbers. edit: To add, the simplification of this performance cost down to percentages completely ignores scale. It's a deceptive statistician's trick. Your favorite browser accidentally releasing a debug/verbose-logging version that consumed in the range of 1-10% more power globally would be significant.
TingPing 4y ago
Asking people to rebuild things isn't at all realistic. Now any user at any moment can get useful information.
- bravetraveler 4y ago
  I don't think it's completely untenable, though I do understand why it wouldn't be preferred. The people served by this change to the defaults are in the minority. I don't buy that a developer that would gift the community with sufficient performance fixes derived from these... wouldn't manage with what's already available. I think either making the processes to rebuild easier/more well known, less costly (time), or transparent (hello, package groups) is more appropriate, personally. I'm not saying it's right, but that's how I sit with this. I want to do better to avoid prescribing the solution. We can do better than paying the cost of profiling constantly. This information is useful to some users sometimes, but may have completely varying impact on performance forever if made the default.
  - TingPing 4y ago
    This change benefits the developers and testers of the platform, with the hope they improve the software in the future. Requiring rebuilding no matter how easy would completely remove all non-dev testers and demotivate the majority of developers.
    - bravetraveler 4y ago
      I understand that angle, and I think edited this point in above before you saw it here... > I don't buy that a developer that would gift the community with sufficient performance fixes derived from these... wouldn't manage with what's already available. I don't think there's much productive to be had at this point, simply a difference in beliefs and theory-crafting I'm particularly 'jaded' about this (negatively hopeful), because they can likely start with a penalty edit: 'We' should do better to provide profiling, but I don't think it's a worthwhile default given the open-ended expense.

pxc 4y ago

Some thorough benchmarks are something I'd love to read about here on HN. If you ever do those benchmarks, post 'em.

bravetraveler 4y ago
I'll be happy to share! I'll probably be waiting for the next release so I can get their pointer-enabled builds. However they do that may give me helpful hints RE: rebuilding the same sources without it. I know the tools to do it, but what I'm imagining right now is a bit convoluted. I'm open to suggestions on things to test. I want to avoid too much reliance on synthetics -- and my 'real world' differs like all of ours My original post has (currently) been down-struck a bit but you're the only reply. I appreciate you taking the time to engage I understand it seems dismissive, perhaps even aggressive, but the Fedora/SuSE people tend to set trends. I just want to measure them. The snark is me finding it ironic that I can (relatively easily) measure this with the same methods they want to avoid... rebuilds with the right options under mock / fedpkg subtext: not that many people find profiling interesting or important... but they will if you start messing with their performance. I find it interesting though so I'm not mad, I just fairly called it self-fulfilling -- I'm going to be profiling because the minority who regularly do, don't want to rebuild (like I will be)
evmar 4y ago
https://docs.kernel.org/x86/orc-unwinder.html https://docs.kernel.org/x86/orc-unwinder.html (which I found when looking up ORC, as mentioned in this thread) has some stats for the Linux kernel on the cost of frame pointers: "5-10%" and "3.49% more cache misses with framepointer enabled and 6.59% more cycles". Between this, the various sorts of C language safety checks compilers have been slowly adding, and all the spectre-related defenses, it really does feel like performance is getting slowly consumed by a series of single-digit percentage tweaks.
- mepian 4y ago
  It's just the time to pay the piper finally arriving, the computer industry ignored security in favor of performance for far too long.
  - nullc 4y ago
    > the computer industry ignored security in favor of performance for far too long Doesn't including an explicit, predictable, frame pointer make life moderately easier for shell code?
- bravetraveler 4y ago
  I agree -- it's easy to think that a few percent here/there don't hurt, but there's no global context on this. Team A takes away ~4% here, B goes on to do ~3%, and so on and so forth. In only five of these, and consider the chains of Pythonic imports you've seen for example, you've lost roughly a quarter of your performance. (grant me an additive/compounding? nature) This is assuming that the measurements taken in a vacuum even hold up to reality. I've seen reports for misc. other things in the 20% range, so my confidence is remarkably low. I'm not against making it easier, but I don't think everyone always need to be ready for profiling. Making opting in easier lets us ignore the hand-wavy numbers. edit: To add, the simplification of this performance cost down to percentages completely ignores scale. It's a deceptive statistician's trick. Your favorite browser accidentally releasing a debug/verbose-logging version that consumed in the range of 1-10% more power globally would be significant.

TingPing 4y ago

Asking people to rebuild things isn't at all realistic. Now any user at any moment can get useful information.

bravetraveler 4y ago
I don't think it's completely untenable, though I do understand why it wouldn't be preferred. The people served by this change to the defaults are in the minority. I don't buy that a developer that would gift the community with sufficient performance fixes derived from these... wouldn't manage with what's already available. I think either making the processes to rebuild easier/more well known, less costly (time), or transparent (hello, package groups) is more appropriate, personally. I'm not saying it's right, but that's how I sit with this. I want to do better to avoid prescribing the solution. We can do better than paying the cost of profiling constantly. This information is useful to some users sometimes, but may have completely varying impact on performance forever if made the default.
- TingPing 4y ago
  This change benefits the developers and testers of the platform, with the hope they improve the software in the future. Requiring rebuilding no matter how easy would completely remove all non-dev testers and demotivate the majority of developers.
  - bravetraveler 4y ago
    I understand that angle, and I think edited this point in above before you saw it here... > I don't buy that a developer that would gift the community with sufficient performance fixes derived from these... wouldn't manage with what's already available. I don't think there's much productive to be had at this point, simply a difference in beliefs and theory-crafting I'm particularly 'jaded' about this (negatively hopeful), because they can likely start with a penalty edit: 'We' should do better to provide profiling, but I don't think it's a worthwhile default given the open-ended expense.