* Roman Zippel <[EMAIL PROTECTED]> wrote: > > jiffies based sched_clock should be soon very rare. It's probably > > not worth optimizing for it. > > I'm not so sure about that. sched_clock() has to be fast, so many > archs may want to continue to use jiffies. [...]
i think Andi was talking about the vast majority of the systems out there. For example, check out the arch demography of current Fedora installs (according to the Smolt opt-in UUID based user metrics): http://smolt.fedoraproject.org/ i686: 74743 x86_64: 18599 i386: 1208 ppc: 527 ppc64: 396 sparc64: 14 --------------- Total: 95488 even pure i386 (kernels, not systems) is a only 1.2% of all installs. By the time the CFS kernel gets into a distro (a few months at minimum, typically a year) this percentage will go down further. And embedded doesnt really care about task-statistics corner cases [ (it likely doesnt have 'top' installed - likely doesnt even have /proc mounted or even built in ;-) ]. of course CFS should not do _worse_ stats than what we had before, and should not break or massively misbehave. Also, anything sane we can do for low-resolution arches we should do (and we already do quite a bit - the while wmult stuff is to avoid expensive divisions) - and i regularly booted CFS with a low-resolution clock to make sure it works. So i'm not trying to duck anything, we've just got to keep our design priorities right :-) Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
