Re: [Fwd: Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.4]

Lee Revell
2004-10-30T20:05:43Z

On Sat, 2004-10-30 at 21:47 +0200, Florian Schmidt wrote:
> Hi, in the meantime i also booted into P9 again and the results differ
> dramatically. Much better in P9. Anyways, i reuploaded the tarball. The
> program tries to detect missed irq's now and counts the total number of
> irq's delivered by /dev/rtc. Since the program does not recover from missed
> irq's the "statistical" data for these runs is useless [except for the
> knowledge of the fact that one or more irq was missed :)]

Here are my results with T3. As expected, much better.

--

rlrevell@mindpipe:~/cvs/wakeup$ ./rt_wakeup 1024 100000 freq: 1024 #:
100000
setting up /dev/rtc.
locking memory...
turning irq on, beginning measurement (might take a while).
done.

total # of irqs: 100000. missed irq's: 0

mean cycle difference betweem two wakeups: 585875 cycles

min. cycle difference betweem two wakeups: 517708 cycles (#: 27478)
diff from mean diff: 68166.8

max. cycle difference betweem two wakeups: 656018 cycles (#: 27477)
diff from mean diff: 70143.2

mean difference from mean difference: 3052.86 cycles

--

So maybe the bug is not related to scheduling of SCHED_FIFO threads, but
that we are missing IRQs. I think this would explain the choppy
playback with mplayer (it uses the RTC and does not run SCHED_FIFO).

Lee