[09:00] <alkisg> Hi, https://wiki.ubuntu.com/Security/Features#Built_as_PIE says that it has 5-10% performance penalty
[09:00] <alkisg> Does that mean that if I run `echo 0 > /proc/sys/kernel/randomize_va_space` on a pentium 4, it'll run Ubuntu 16.04 faster?
[09:05] <alkisg> Or compiling with PIE enabled will result in performance loss anyway?
[10:21] <apw> compiling as PIE will alter the emitted code
[10:22] <alkisg> apw: I mean, does PIE mean a syscall that can be disabled in the kernel at runtime, avoiding the extra overhead, or is it a compiler time thing only, which cannot be disabled after compilation?
[10:23] <apw> pie is a compilation option which changes the code to not assume its location, which has a cost associated with it
[10:24] <alkisg> apw, thank you, so the only way to measure that overhead would be to recompile, which isn't really an option if one wants to use a recent Ubuntu version :)
[10:24] <apw> right, you'd need to turn it off and rebuild the kernel
[10:24] <alkisg> The kernel or the apps?
[10:25] <alkisg> I thought that was about the apps...
[10:25] <apw> both indeed, depends what you are trying to measure
[10:25] <alkisg> Well in general how much slower a "desktop feels", maybe that would be 80% userspace and 20% kernel...
[10:26] <apw> hard to say indeed, and humans are immensly sensitive to that kind of thing
[10:26] <alkisg> E.g. a few years ago it was possible to watch youtube with a p4 1.7 ghz, now it's not even with p4 at 2.4 ghz
[10:26] <apw> a few % and you can tell often
[10:26] <apw> are the videos at the same resolution i wonder
[10:26] <alkisg> Yes, but I'm not sure about the players
[10:27] <apw> but it doesn't supprise me entierly, old h/w does get left behind over time
[10:27] <apw> i wonder how old a pentium-4 mbased mchine could be at its youngest now
[10:27] <alkisg> I used the same video back then and now, and tried with flash now as well as then when html5 didn't exist, but I don't know if flash or youtube added unrelated code that made them slower
[10:29] <apw> browsers are more tightly controlled now days too
[10:29] <apw> and video playback is one of those things where your computer is either fast enough or not
[10:29] <alkisg> And there's compositing even in the legacy desktops, adding to delays... https too...
[10:29] <alkisg> Ah, playing with vlc is fast now too
[10:29] <apw> it might have been 1% faster than needed before and be 2% slower now and ... you lose
[10:30] <alkisg> The browsers make it like 4 times slower
[10:30] <apw> so it is ok in vlc ?
[10:30] <alkisg> Yeah
[10:30] <apw> so not inherantly unplayable then
[10:30] <alkisg> Ubuntu 16.04 i386 is still fast enough to play an e.g. 1024x768 full screen movie without dropped frames
[10:31] <alkisg> Indeed, but there's no way to convince youtube/firefox etc etc to make them more efficient for older machines, so I was looking to gain that 10% performance in case it makes things barely more functional
[10:33] <alkisg> apw: so with regards to aslr/pie, we're not expecting any performance differences between e.g. 12.04 and 18.04, since all "major" programs like the kernel or firefox were already using them, correct?
[10:33] <apw> that'd be my feeling
[10:34] <alkisg> Thank you, I was worried that I would have to hold those machines with 16.04
[10:34] <alkisg> Let them work with 18.04 as long as they have a bit of life in them
[10:40] <apw> alkisg, as with all things, testing it out is a good plan
[10:41] <alkisg> Indeed... hmm I'll actually do a larger comparison, 10.04/12.04/18.04 live cds, and watching the same youtube video...
[10:42] <apw> sounds like "fun"