Niklaus Giger wrote:
Am Montag, 25. September 2006 17:57 schrieb Philippe Gerum:
On Sun, 2006-09-24 at 23:07 +0200, Wolfgang Grandegger wrote:
Niklaus Giger wrote:
<..>
Ok, we can go for the lazy fix here, since this code is poised to
disappear anyway. I've merged a variant of the above we already use for
the ARM port, which scales down the period to microseconds instead of
losing precision on the count of timebase ticks per jiffy.
- ticks = ns * tb_ticks_per_jiffy / (1000000000 / HZ);
+ ticks = (ns / 1000) * tb_ticks_per_jiffy / (1000000 / HZ);
Thanks for finding this solution. I tried to understand mulhwu and
mulhwu_scale_factor but couldn't figure out a correct solution in a short
time.
I took me also some time to understand the meaning. mulhwu(a,b) returns
the high 32 bits (32..63) of a*b. A possible quick fix could be:
if (mulhwu(ns, tb_ticks_per_jiffy) > 0)
ticks = (ns / 1000) * tb_ticks_per_jiffy / (1000000 / HZ);
else
ticks = ns * tb_ticks_per_jiffy / (1000000000 / HZ);
But Philippe already applied a reasonable fix.
The buildbot cannot presently power on and off my PPC405 target board, as the
my power outlet switching device is broken and has been sent back for a
remplacement.
I did however run some tests manually and have the following questions about
the output:
Why do I get negative values for latenciy values?
Is the output of lines like "Xenomai: Switching display-3238 to secondary mode
after exception #1025 from user-space at 0x100033c4 (pid 3240)" harmless or
the result of a activated CONFIG_XENO_OPT_DEBUG<..> option?
Mon Sep 25 20:20:33 UTC 2006
running: ./run -- -T 5 -t2 # latency
*
*
* Type ^C to stop this application.
*
Xenomai: Switching display-3238 to secondary mode after exception #1025 from
user-space at 0x100033c4 (pid 3240)
== Sampling period: 100 us
== Test mode: in-kernel timer handler
== All results in microseconds
warming up...
RTT| 00:00:01 (in-kernel timer handler, 100 us period, priority 99)
RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst
RTD| -5.108| -4.754| -0.905| 0| -5.108| -0.905
RTD| -4.963| -4.871| 1.155| 0| -5.108| 1.155
Xenomai: Switching display-3238 to secondary mode after exception #1025 from
user-space at 0xfda9638 (pid 3240)
RTD| -4.963| -4.758| 16.020| 0| -5.108| 16.020
RTD| -6.313| -4.861| 10.980| 0| -6.313| 16.020
Xenomai: Switching display-3238 to secondary mode after exception #1025 from
user-space at 0xfe7c1c4 (pid 3240)
---|------------|------------|------------|--------|-------------------------
RTS| -6.313| -4.811| 16.020| 0| 00:00:05/00:00:05
Xenomai: stopping RTDM services.
Best regards
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