Messages in this thread | | | From | Con Kolivas <> | Subject | Re: [REPORT] cfs-v4 vs sd-0.44 | Date | Sun, 22 Apr 2007 01:55:20 +1000 |
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On Saturday 21 April 2007 22:12, Willy Tarreau wrote: > I promised to perform some tests on your code. I'm short in time right now, > but I observed behaviours that should be commented on.
> Feels even better, mouse movements are very smooth even under high load. > I noticed that X gets reniced to -19 with this scheduler. I've not looked > at the code yet but this looked suspicious to me.
Looks like this code does it:
+int sysctl_sched_privileged_nice_level __read_mostly = -19;
allows anything that sets sched_privileged_task one way or another gets nice -19, and this is enabled by default.
--- linux-cfs-2.6.20.7.q.orig/arch/i386/kernel/ioport.c +++ linux-cfs-2.6.20.7.q/arch/i386/kernel/ioport.c
+ if (turn_on) { + if (!capable(CAP_SYS_RAWIO)) + return -EPERM; + /* + * Task will be accessing hardware IO ports, + * mark it as special with the scheduler too: + */ + sched_privileged_task(current); + }
presumably that selects out X as a privileged task... and sets it to nice -19 by default.
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