On Tue, Apr 17, 2007 at 03:59:02PM -0700, William Lee Irwin III wrote: > On Tue, Apr 17, 2007 at 03:32:56PM -0700, William Lee Irwin III wrote: > >> 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. > > On Tue, Apr 17, 2007 at 05:39:09PM -0500, Matt Mackall wrote: > > Good. This has a couple nice mathematical properties, including > > "bounded unfairness" which I mentioned earlier. What base are you > > looking at? > > I'm working with the following suggestion: > > > On Tue, Apr 17, 2007 at 09:07:49AM -0400, James Bruce wrote: > > Nonlinear is a must IMO. I would suggest X = exp(ln(10)/10) ~= 1.2589 > > That value has the property that a nice=10 task gets 1/10th the cpu of a > > nice=0 task, and a nice=20 task gets 1/100 of nice=0. I think that > > would be fairly easy to explain to admins and users so that they can > > know what to expect from nicing tasks. > > I'm not likely to write the testcase until this upcoming weekend, though.
So that means there's a 10000:1 ratio between nice 20 and nice -19. In that sort of dynamic range, you're likely to have non-trivial numerical accuracy issues in integer/fixed-point math. (Especially if your clock is jiffies-scale, which a significant number of machines will continue to be.) I really think if we want to have vastly different ratios, we probably want to be looking at BATCH and RT scheduling classes instead. -- Mathematics is the supreme nostalgia of our time. - 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/