From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <53E3CD23.5040909@xenomai.org> Date: Thu, 07 Aug 2014 21:01:55 +0200 From: Philippe Gerum MIME-Version: 1.0 References: <44BE6908-E639-421F-B556-E7B3871402CF@gmail.com> <67B7E374-C4D2-4F83-BA40-B289B15867B9@tuebingen.mpg.de> <53E3B5E3.3090006@xenomai.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai] real-time guarantee issues on xenomai 2.6.2.1 List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paul Janzen , xenomai@xenomai.org On 08/07/2014 08:47 PM, Paul Janzen wrote: > Gilles Chanteperdrix writes: > >> And it also probably happens in some conditions only (with a large >> number of Xenomai threads for instance) > > This is not quite correct. I experience large latencies (~1ms) during > "watch cat /proc/xenomai/stat", just running xeno-test (stat lists two > application tasks, two ROOTs and two IRQ-timers.) > > x64, SMP, Linux 3.4.6, ipipe-core-3.4.6-x86-4.patch, xenomai 242a6e4. > 1 ms is definitely pathological. This cannot be related to /proc/xenomai/stat or whatever vfile under /proc/xenomai, we would have noticed. This is more likely a I-pipe issue (3.4.6/x86 is outdated, although 1 ms is really above usual issues), a kernel configuration issue (e.g. CONFIG_CPU_FREQ, or other latency killer), or maybe a SMI problem. Or maybe an issue induced by a graphic card driver if you happen to run with a GUI. -- Philippe.