From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gilles Chanteperdrix MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17486.10146.597736.78655@domain.hid> Date: Tue, 25 Apr 2006 15:44:02 +0200 Subject: Re: [Xenomai-help] Posix skin illegal seek on sem_wait In-Reply-To: <20060425134316.017836e8@domain.hid> References: <20060425134316.017836e8@domain.hid> List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Daniel Simon Cc: xenomai@xenomai.org Daniel Simon wrote: > What makes the difference between a Xenomai thread and an ordinary nptl > thread, other than the compilation and linking flags? The term "Xenomai thread" comes from the document "Life with Adeos": http://snail.fsffrance.org/www.xenomai.org/documentation/trunk/pdf/Life-with-Adeos-rev-B.pdf A Xenomai thread is a thread known by Xenomai scheduler. Ordinary linuxthread or NPTL threads are known by Xenomai scheduler once they acquire a "shadow" thread. With the posix skin, an ordinary thread is created with a shadow thread if you use the pthread_create service with the policy attribute (whether explicit or inherited) set to SCHED_FIFO, or an ordinary thread may acquire a shadow thread if this ordinary thread calls the pthread_setschedparam service passing the value SCHED_FIFO as the policy argument. Please also note that for now, signals sent by the timer_* services will cause migration of the target thread to secondary mode, which means that the jitter will not be better for Xenomai threads than for ordinary threads. For good timings, you should use the nanosleep or clock_nanosleep services, or alternatively the non portable extensions pthread_make_periodic_np and pthread_wait_np. For other details about Xenomai implementation of the POSIX API, see: http://snail.fsffrance.org/www.xenomai.org/documentation/trunk/html/api/group__posix.html -- Gilles Chanteperdrix.