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Date: Thu, 27 Aug 2009 14:05:52 +0200
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Subject: Re: [Xenomai-help] Negative Latency results
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To: Christoph Permes <christoph.permes@domain.hid>
Cc: xenomai@xenomai.org

Christoph Permes wrote:
> Hi,
> 
> I'm working together with Peter on the latency problem.
> 
> I have attached our kernel configuration and the boot log to this mail.
> 
> We have tried out configuring a latency between 0 and 10000 but this
> didn't help.

Ok. Could you try the following patch:

diff --git a/include/asm-generic/bits/timeconv.h
b/include/asm-generic/bits/timeconv.h
index 9a89fe9..654f17f 100644
--- a/include/asm-generic/bits/timeconv.h
+++ b/include/asm-generic/bits/timeconv.h
@@ -37,6 +37,11 @@ long long xnarch_tsc_to_ns_rounded(long long ticks)
        unsigned int shift = tsc_shift - 1;
        return (xnarch_llmulshft(ticks, tsc_scale, shift) + 1) / 2;
 }
+
+long long xnarch_ns_to_tsc(long long ns)
+{
+       return xnarch_llimd(ns, 1 << tsc_shift, tsc_scale);
+}
 #else  /* !XNARCH_HAVE_LLMULSHFT */
 long long xnarch_tsc_to_ns(long long ticks)
 {
@@ -46,12 +51,12 @@ long long xnarch_tsc_to_ns_rounded(long long ticks)
 {
        return (xnarch_llimd(ticks, 1000000000, cpufreq/2) + 1) / 2;
 }
-#endif /* !XNARCH_HAVE_LLMULSHFT */

 long long xnarch_ns_to_tsc(long long ns)
 {
        return xnarch_llimd(ns, cpufreq, 1000000000);
 }
+#endif /* !XNARCH_HAVE_LLMULSHFT */

 static inline void xnarch_init_timeconv(unsigned long long freq)
 {


-- 
                                          Gilles