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From: Per Oberg <pero@wolfram.com>
To: xenomai <xenomai@xenomai.org>
Subject: Re: [Xenomai] What does activating SMP mean?
Date: Mon, 1 Oct 2018 02:42:18 -0500 (CDT)	[thread overview]
Message-ID: <590994061.262338.1538379738455.JavaMail.zimbra@wolfram.com> (raw)
In-Reply-To: <759115071.1538372023382.JavaMail.root@webmail>

Hello

----- Den 1 okt 2018, på kl 7:33, 박재호 jaeho@seoultech.ac.kr skrev:

> Hi, all

> I thought that activating SMP makes tasks using all cpu cores, but I realized
> that it doesn't.

> I did not explicitly specify the CPU when I created the task.

> I have created two xenomai tasks and checked to see how much cpu share the task
> has on any cpu with / proc / xenomai / stat.

> As a result, we confirmed that only one cpu of two cpu works.

> So we used T_CPU () to allocate different CPU cores for each task when we
> created the task.

> As a result, you can see that both tasks are running on two CPUs.

> I expected to use both CPUs when I enabled SMP, but I did not. Why is not it?

> Also, does one task only run on one cpu?

> The environment I used is shown below.

> ------------------------------------------------------------------------

> zybo-z7-20(zynq-7000)

> Dual-Core ARM Coretex-A9 MPCore Up to 866MHz

> xenomai 2.6.5

> kernel 3.14.2

> ubuntu 14.04

> ------------------------------------------------------------------------

> thank you for your advice.

> _______________________________________________
> Xenomai mailing list
> Xenomai@xenomai.org
> https://xenomai.org/mailman/listinfo/xenomai

Not sure that I can answer your question as it was formulated, but perhaps I can contribute with something. Do your test-task use all your CPU time or do you have idling? I would -guess- that as long as one CPU is sufficient the scheduler won't use any other unless it was specified on the command-line.

I answer, even though I am not sure about this  because I would like to be corrected if I'm wrong. 

Regards
Per Öberg


  reply	other threads:[~2018-10-01  7:42 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-01  5:33 [Xenomai] What does activating SMP mean? 박재호
2018-10-01  7:42 ` Per Oberg [this message]
2018-10-01  7:48   ` Jan Kiszka

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