From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4AC5AD7C.7010208@domain.hid> Date: Fri, 02 Oct 2009 09:36:28 +0200 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <71396b5b0910010109h5cb5912el7eee9d071ed23cda@domain.hid> <71396b5b0910020021n44f2bc22md97b14e389128486@domain.hid> In-Reply-To: <71396b5b0910020021n44f2bc22md97b14e389128486@domain.hid> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [Xenomai-help] Strange issue : high latency for kernel task when a user task is stop List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gilles FRITZ Cc: xenomai@xenomai.org Gilles FRITZ wrote: > Hi, >=20 > I use Xenomai since not very long, but I have seen a strange behavior := when > I stop a user-space task, my in-kernel task have a latency of about 500= =C2=B5s. >=20 > I have observed that on Xenomai 2.4.8 and 2.3.4, on kernel 2.6.25.19 an= d > 2.6.28.9. >=20 > To observe that, I launch two latency test : one in user-space and the > second in kernel-space > latency -p 50 -t 1 > latency -p 70 >=20 > When I stop the second latency (in user-space), I can observe a latency= of > at least 500ms in the in-kernel task. >=20 > I do not know if this is normal or not. >=20 > Have you an explanation for that? I do not think we have but: - 50us and 70us are a bit short periods depending on the platform (though it should not change anything to use larger periods), and you did not tell us on what platform you are running xenomai - the I-pipe patch proposes an option, the I-pipe tracer, which will tell you exactly what happens during these 500us. --=20 Gilles.