On Thu, Jan 21, 2016 at 9:37 AM, <Valdis.Kletnieks@xxxxxx> wrote: > On Thu, 21 Jan 2016 08:51:08 -0800, John Locke said: > >> * Nice levels are multiplicative, with a gentle 10% change for every >> * nice level changed. I.e. when a CPU-bound task goes from nice 0 to >> * nice 1, it will get ~10% less CPU time than another CPU-bound task > > Note the ~ indicating approximately. > >> If I take an example of 2 tasks both with weight=1024 (NICE_0) they >> should each get 50% of the CPU time. If 1 of the tasks is reniced to >> NICE_1 then the NICE_0 task will get 1024/(1024+820)=56% of the CPU >> time and the NICE_1 task will get 44% of the CPU time. > > 12% difference - that's around 10%. > That's true but depending on what nice levels I choose it can be off by more. If I increase the distance between 'nice' levels, e.g. using -20 and -9 then I get (88761+7620)/96381 or 92% CPU time vs 8%. I guess the real question is if I were given a set of tasks running on the system and their 'nice' levels could I quantify roughly how much CPU time CFS would give them? The ~10% guideline is nice but doesn't hold if the spread between 'nice' levels is larger it seems. _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
