On Tue, Apr 17, 2007 at 11:24:22AM +0200, Ingo Molnar wrote: >> yeah. If you could come up with a sane definition that also translates >> into low overhead on the algorithm side that would be great!
On Tue, Apr 17, 2007 at 05:08:09PM -0500, Matt Mackall wrote: > How's this: > If you're running two identical CPU hog tasks A and B differing only by nice > level (Anice, Bnice), the ratio cputime(A)/cputime(B) should be a > constant f(Anice - Bnice). > Other definitions make things hard to analyze and probably not > well-bounded when confronted with > 2 tasks. > I -think- this implies keeping a separate scaled CPU usage counter, > where the scaling factor is a trivial exponential function of nice > level where f(0) == 1. Then you schedule based on this scaled usage > counter rather than unscaled. > I also suspect we want to keep the exponential base small so that the > maximal difference is 10x-100x. I'm already working with this as my assumed nice semantics (actually something with a specific exponential base, suggested in other emails) until others start saying they want something different and agree. -- 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/
