Re: [Xenomai-core] CPU utilization question
On 10/25/2011 04:18 PM, makarand pradhan wrote: > [MP]: Yes. I've noticed that the sum of all tasks is always 100. My > question was specifically about a xenomai task that transitions in > secondary. > > e.g. Assume a xenomai task that uses a total of 20% CPU. Of this > assume that 10% is spent executing system calls in secondary domain > and 10% is spent in the primary domain. I believe that from an > accounting perspective, 10% would get accounted against ROOT and the > xenomai task will show a CPU util of 10%. Is this accurate? Yes. -- Gilles. ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] CPU utilization question
Hi Gilles, Appreciate your response. Pl find comments inline. From: Gilles Chanteperdrix To: makarand pradhan Cc: "xenomai-core@gna.org" Sent: Tuesday, October 25, 2011 4:50 AM Subject: Re: [Xenomai-core] CPU utilization question On 10/25/2011 12:19 AM, makarand pradhan wrote: > (...) I'm > assuming that the ROOT thread captures the %CPU spent in > Linux/secnodary and each xenomai thread listed, captures the %CPU in > primary domain. If a thread transitions to the secondary, then I'm > assuming that the %util in secondary domain will get accounted > against ROOT and the actual % usage in primary will get accounted > against the thread. You are assuming wrong, the CPU utilization measures the activity of the linux kernel as a whole, including its idle task. So, the sum of all the primary mode tasks and of the ROOT task is always 100%. [MP]: Yes. I've noticed that the sum of all tasks is always 100. My question was specifically about a xenomai task that transitions in secondary. e.g. Assume a xenomai task that uses a total of 20% CPU. Of this assume that 10% is spent executing system calls in secondary domain and 10% is spent in the primary domain. I believe that from an accounting perspective, 10% would get accounted against ROOT and the xenomai task will show a CPU util of 10%. Is this accurate? > Question: > > If the linux process is sleeping, why do I see a CPU util against the > process? Why is the CPU % util vary based on the activity I do in the > primary domain? rt_printf is a primary mode service which causes activity in secondary mode: the actual printf is done by a plain linux task. [MP]: Tx. It helped. I've taken the rt_printfs out and now my Linux process that started the xenomai task shows 0% as expected. PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 5136 root 20 0 4936 4372 3688 S 0.0 0.8 0:00.04 a.out Rgds, Makarand. -- Gilles.___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] CPU utilization question
On 10/25/2011 12:19 AM, makarand pradhan wrote: > (...) I'm > assuming that the ROOT thread captures the %CPU spent in > Linux/secnodary and each xenomai thread listed, captures the %CPU in > primary domain. If a thread transitions to the secondary, then I'm > assuming that the %util in secondary domain will get accounted > against ROOT and the actual % usage in primary will get accounted > against the thread. You are assuming wrong, the CPU utilization measures the activity of the linux kernel as a whole, including its idle task. So, the sum of all the primary mode tasks and of the ROOT task is always 100%. > Question: > > If the linux process is sleeping, why do I see a CPU util against the > process? Why is the CPU % util vary based on the activity I do in the > primary domain? rt_printf is a primary mode service which causes activity in secondary mode: the actual printf is done by a plain linux task. -- Gilles. ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
[Xenomai-core] CPU utilization question
Greetings all, I am working on a real time power pc embedded system which uses xenomai. I am presently noticing a CPU utilization which I am not able to explain. Will highly appreciate your opinion on the problem described below. I'm summarizing my understanding. Pl feel free to correct me. I'm using /proc/xenomai/stat to get the CPU util. I'm assuming that the ROOT thread captures the %CPU spent in Linux/secnodary and each xenomai thread listed, captures the %CPU in primary domain. If a thread transitions to the secondary, then I'm assuming that the %util in secondary domain will get accounted against ROOT and the actual % usage in primary will get accounted against the thread. Problem: I'm starting a xenomai thread using rt_task_spawn. rt_task_spawn(&task2, "Task 2 ", STACK_SIZE, 11, 0, task2_func, NULL); The thread invoking rt_task_spawn, sleeps for a long long time without doing anything, or I can pause it. sleep(500); The xenomai task does rt_printfs periodically. With this setup, I was hoping to see 0% CPU util for the linux task in top. Contrary to this expectation, I notice CPU util as high as 3.1% when I top the linux process: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 7988 root 20 0 4940 4376 3688 S 3.1 0.8 0:01.65 a.out The CPU % varies based on the activity I do in the primary domain. i.e. more rt_printfs more %CPU in both primary and secondary. Question: If the linux process is sleeping, why do I see a CPU util against the process? Why is the CPU % util vary based on the activity I do in the primary domain? Thanks for taking the time to look at the question. Would highly appreciate your inputs. Warm Rgds, Makarand.___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
