From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4AF88A77.4030902@domain.hid> Date: Mon, 09 Nov 2009 22:32:39 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <47a3101a0911070704o5307a23dhef368d04cc25fc6@domain.hid> <4AF59B0F.1020300@domain.hid> <47a3101a0911072306g42ddc0dfld0571e04fe1bf18b@domain.hid> <4AF6AA34.3040308@domain.hid> <4AF6E380.3010703@domain.hid> <47a3101a0911080922x1eda27ccja276c3f1a06e0941@domain.hid> <4AF701AC.5050702@domain.hid> <748872BF-565F-4637-BDBC-6534B04DFA24@domain.hid> In-Reply-To: <748872BF-565F-4637-BDBC-6534B04DFA24@domain.hid> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] Gumstix arm pxa List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Schaal Cc: Xenomai help , Linus Casassa Stefan Schaal wrote: > Hi Gilles, > > if aperiodic has better accuracy, what is the minimal time > resolution one can obtain, e.g., on a x86 (I assume that asking for > too short a wait can lead to system freezes)? Coming from the vxWorks The sleep time resolution is bound to the frequency of the hardware timer used. I do not know x86 details that much, but I seem to remember that the 8254 timer, the worst one, has a frequency around 1 MHz, which gives you a resolution of 1us, enough for most uses I believe. > philosophy, we have been running a 100000ns periodic clock (x86) to > work with semaphores and timing statements. Seemingly, you recommend > not to use the periodic clock. The rt_timer_ns2ticks and > rt_timer_ticks2ns seem to return 0 if the aperiodic clock is used. Is > this reasonable, or should they return that ticks and nanoseconds have > the same value in this case? > > Sorry, I am just learning about this different way of using a ROS. either your system is misconfigured (if you have a periodic timer, any time duration smaller than the timer period will give you a duration of 0 ticks, results are rounded toward 0), or there is a bug somewhere. cat /proc/xenomai/timebases will tell you. What xenomai version are you using exactly ? -- Gilles.