Gilles Chanteperdrix wrote: > Jan Kiszka wrote: >> Jan Kiszka wrote: >> >>> Jan Kiszka wrote: >>> ... >>> >>>> fast-tsc-to-ns-v2.patch >>>> >>>> [Rebased, improved rounding of least significant digit] >>> Rounding in the fast path for the sake of the last digit was silly. >>> Instead, I'm now addressing the ugly interval printing via >>> xnarch_precise_tsc_to_ns when converting the timer interval back into >>> nanos. -v3 incorporating this has just been uploaded. >>> >> >> After noticing yesterday that even unpatched Xenomai sometimes converts >> inaccurately when showing small timer intervals under /proc, I just got >> an idea how to address this beautification issue even better: -v4 now >> rounds up in the slow, precise tsc-to-ns path, see >> >> http://www.rts.uni-hannover.de/rtaddon/patches/xenomai/fast-tsc-to-ns-v4.patch > > I am the one who decided of the rounding behaviour of llimd, RTAI > version had the same rounding policy as the one you propose, and I made > it for the following reasons: > - rouding towards 0 is the policy used by the C language, so doing this > for llimd made it consistent with what one expects from C code; > - values computed by llimd are used to program timers, and we prefer the > timer to be programmed for a too short value than for a too long value.
That's OK, I agree. In my patch for i386, this rounding is only relevant for display purposes. It's just to help me finding the expected period T of my task in /proc instead of T-1 sometimes. Beautification. All we need for other archs is xnarch_tsc_to_ns according to the old scheme. Will rework this. Jan
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