Hi, Without the support of High Resolution Timer supported, the timer resolution wouldn't change. With high-resolution-timer supported, our arm926-based board could get resolution like 40~50us. There are codes you can reference ,may be you should just try to implement it.
JFI, Thanks. From: tike64 <[EMAIL PROTECTED]> Subject: realtime-preempt and arm Date: Wed, 29 Nov 2006 00:57:05 -0800 (PST) > Hi all, > > I'm trying the realtime-preempt patch-2.6.18-rt6 on > lh7a400 arm system with little success. In a test > program I try 5 ms timeout with select() but get 20 ms > avg or 26 ms max. When the framebuffer scrolls, the > max delay goes up to 59 ms. With a vanilla kernel I > get 10 ms (because of tick resolution?), 11 ms and 39 > ms. > > My question is, is the realtime-preempt patch supposed > to work on arm architecture and/or without high > resolution timer (which lh7a40x seems to lack) at all > or should I just try to be more clever. > > Relevant code: > > ==== > prio.sched_priority = 99; > if (sched_setscheduler(0, SCHED_RR, &prio) < 0) ... > if (mlockall(MCL_CURRENT | MCL_FUTURE) < 0) ... > while (1) { > t = raw_timer(); > tv.tv_usec = 5000; > tv.tv_sec = 0; > select(0, 0, 0, 0, &tv); > t = raw_timer() - t; > if (max_t < t) max_t = t; > if (min_t > t) min_t = t; > avg_t += t; > ++n; > if (n < 100) continue; > printf("%i revs; min: %i max: %i avg: %i\n", > n, > min_t, > max_t, > (avg_t + n / 2) / n); > ==== > > Relevant config: PREEMPT_RT, PREEMPT_SOFTIRQS, > PREEMPT_HARDIRQS > > I didnt' enable HIGH_RES_TIMERS because lh7a40x seems > not to support it. > > -- > > tike > > > > > ____________________________________________________________________________________ > Cheap talk? > Check out Yahoo! Messenger's low PC-to-Phone call rates. > http://voice.yahoo.com > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [EMAIL PROTECTED] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/