* Ting Yang <[EMAIL PROTECTED]> wrote: >> then how much time is needed for "curr" to build a 2 * 32 difference >> on fair_key, with every 1 ms it updates fair_key by 1/32 ? 2 * 32 * >> 32 !
On Thu, May 03, 2007 at 09:48:27PM +0200, Ingo Molnar wrote: > yes - but the "*32" impacts the rescheduling granularity, the "/32" > impacts the speed of how the key moves. So the total execution speed of > the nice -10 task is still "*32" of a nice 0 task - it's just that not > only it gets 32 times more CPU time, it also gets it at 32 times larger > chunks at once. But the rescheduling granularity does _not_ impact the > CPU share the task gets, so there's no quadratic effect. > but this is really simple to test: boot up CFS, start two infinite > loops, one at nice 0 and one at nice +10 and look at it via "top" and > type 's 60' in top to get a really long update interval for precise > results. You wont see quadratically less CPU time used up by the nice > +10 task, you'll see it getting the intended 1/32 share of CPU time. Davide has code to test this more rigorously. Looks like I don't need to do very much to get a nice test going at all, besides fiddling with options parsing and maybe a few other things. -- wli - 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/
