From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4EFD910F.3080404@domain.hid> Date: Fri, 30 Dec 2011 11:23:11 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <4EFCFF53.7040508@domain.hid> In-Reply-To: <4EFCFF53.7040508@domain.hid> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] Mode switches?? List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Terry Fryar Cc: xenomai@xenomai.org On 12/30/2011 01:01 AM, Gilles Chanteperdrix wrote: > On 12/29/2011 10:43 PM, Terry Fryar wrote: >> Using 2.6.0, I am have trouble understanding the results of the >> rt_task_info() call? >> >> Have a very simple kernel module that fires off an ISR routine and a xenomai >> task. The IRQ is not firing for these tests, so it's not doing anything. >> Here's the xenomai rt task created using rt_create_task(): >> >> void irqdrv_task(void *args) >> { >> while (!irqdrv_terminated) >> { >> rt_task_sleep(10000000); >> } >> } >> >> So, in the driver "exit" code, right before I delete this task I do a >> rt_task_info() and I see no context switches and very little exec time for >> this task. However, it's showing 1,000,000 mode switches in just 5 or 10 >> seconds of exec time?? >> >> The info.modeswitches is the number of times the task switches between >> primary and secondary mode, yes?? Why in the world are there so many for a >> small task doing nothing but call a xenomai function, and in a kernel driver >> to boot!! >> >> Am I missing something here....shouldn't mode switches be zero??? I'm not >> calling any linux kernel functions...it shouldn't have switched ever?? > > mode switches do not exist for kernel-space tasks. So, reading the > modeswitch member of the task info structure for a kernel space task > does not really make sense. Which is why probably nobody else noticed > (that, and the fact that the native API in kernel-space is not very much > in use, these days). > the mode switches count should still be zero. Could you show us the full test code? -- Gilles.