From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <47B07FA4.8050801@domain.hid> Date: Mon, 11 Feb 2008 18:02:28 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <51CAD0CE1504444DBE77CBBE51A0135D376AD7@domain.hid> <47B053A2.9010503@domain.hid> <51CAD0CE1504444DBE77CBBE51A0135D376ADB@slcmail.slc.mew.int> In-Reply-To: <51CAD0CE1504444DBE77CBBE51A0135D376ADB@slcmail.slc.mew.int> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] overhead List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Steven Seeger Cc: xenomai@xenomai.org Steven Seeger wrote: > The overhead was measured by only comparing cpu usage between tasks from > the statistics collection stuff. There are some userland tasks running > at 8khz, so apparently this is a problem for Xenomai on this board. I > had no problem at all with these tasks in kernel space under rtai. > > There are no faults at all under /proc/xenomai/faults. > > The main way I can tell something is wrong is that if my three fast > tasks are running (8 khz in kernel space, 8 khz in userspace, and 50 hz > in userspace) then a lower priority task will timeout and trip a > watchdog. If I remove the IO routines from the 50hz task, then the > others can still run. I/O does not come for free (specifically on ISA HW - if that is the case for you). But if you think that this makes a difference here, what about measuring both kernel- and userland-based I/O accesses in a loop and compare the runtime? This would also allow you to quantify the impact - regardless if there is a difference or not. Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux