From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <50129907.5040306@siemens.com> Date: Fri, 27 Jul 2012 15:35:03 +0200 From: Jan Kiszka MIME-Version: 1.0 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai] cpu usage List-Id: Discussions about the Xenomai project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Frederik Bayart Cc: "xenomai@xenomai.org" On 2012-07-27 15:04, Frederik Bayart wrote: > I'm running Xenomai 2.6.0 on Linux 2.6.38 > > I have a dual core processor. > When I run a busywait loop on cpu 0 (see source in attachment), I > can't do anything anymore on the computer although cpu 1 is almost > entirely idle. I can't interrupt the busywait loop, login, type > something in a shell, ... > This is even the case if I run linux entirely on cpu 1 (by using > isolcpus=0 as kernel parameter) > > How can this be explained ? > > Is it possible to use cpu 0 at 100% for a xenomai tasks and cpu 1 for > normal linux tasks so that you can still work on the computer ? It's a FAQ: This is not possible with current Linux. It will lock up quite quickly if kernel helper threads for RCU or work queues cannot run once in a while. Also, time keeping will be affected. Due to the latter, you should release the core to Linux once every scheduling tick. Jan -- Siemens AG, Corporate Technology, CT RTC ITP SDP-DE Corporate Competence Center Embedded Linux