Hi Gilles,

"No, CLOCK_PROCESS_CPUTIME is a clock= implemented by the Linux kernel,
so, it does not see the time spent in = primary mode. If the foo function
does not suspend, you can use rt_timer= _tsc(), but the answer is no,
there is currently no way to get the cpu t= ime used when in primary mode."

Thanks a lot for the explanation.= It seems my understanding on how Xenomai works was incorrect. I thought th= at if a task, say, myRTTask() is spawned by rt_task_create() and rt_task_st= art(), then myRTTask() will always run in the primary mode, so if myRT= Task() calls foo(), then foo() will be running in the primary mode all the = time. The correct fact is, myRTTask() could be running in either the primar= y mode or the secondary mode, right? This arises my another question, if foo() uses some third party libraries (with source code available), how ca= n I tell what parts of foo() will be running in the primary mode, and what = parts will be in the secondary mode? Are there principles for deciding whet= her the code is in the primary mode or the secondary mode?

Thanks again for your patient help.

Tom

From: Gilles Chanteperdrix <g= illes.chanteperdrix@domain.hid>
Cc: "xenomai@xenomai.org" <xenomai@xenomai.org= g>
Sent: Friday, 4 N= ovember 2011 4:36 PM
Subject: = Re: [Xenomai-help] 0 CPU time problem

On 11/04/2011 10:03 PM,= Tom Z wrote:
> > We do not know what skin you use, we will assume= that you use
> > Xenomai posix skin, so, compile with the right f= lags.
>
> Here is how I
> build my program, say, fooTest:= gcc -I/usr/xenomai/include
> -D_GNU_SOURCE -D_REENTRANT -Wall -pipe = -D__XENO__ -lnative
> -L/usr/xenomai/lib -lxenomai -lpthread -lnative= -lrtdk fooTest.c -o
> fooTest

You are using the native skin t= hen.

> > CLOCK_PROCESS_CPUTIME_ID is not implemented for xenom= ai posix skin,
> > so, clock_gettime probably returns an error, an= d the struct timespec
> > is unchanged. If somehow the glibc clock= _gettime is used, and this
> > call does not cause a system call, = then all bets are off, and even a
> > lockup could happen.
>
> Thanks for explaining this. So can I trust the
= > CPU time I obtained with my method when the function is running in
= > the primary mode? It seems you explanation implies that the results I<= br>> obtained are not reliable, if so, are there other reliable ways to<= br>> obtain the CPU time?

No, CLOCK_PROCESS_CPUTIME is a clock im= plemented by the Linux kernel,
so, it does not see the time spent in pri= mary mode. If the foo function
does not suspend, you can use rt_timer_ts= c(), but the answer is no,
there is currently no way to get the cpu time= used when in primary mode.

--
= ; &nb= sp; &= nbsp; Gilles.

--573995543-253283875-1320460319=:56312-- From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4EB51D8E.9020609@domain.hid> Date: Sat, 05 Nov 2011 12:27:10 +0100 From: Philippe Gerum MIME-Version: 1.0 References: <1320433713.81220.YahooMailNeo@domain.hid> <4EB43B3E.806@domain.hid> <1320440601.64091.YahooMailNeo@domain.hid> <4EB45AF6.60304@domain.hid> In-Reply-To: <4EB45AF6.60304@domain.hid> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] 0 CPU time problem List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: xenomai@xenomai.org, tomz30@domain.hid On 11/04/2011 10:36 PM, Gilles Chanteperdrix wrote: > On 11/04/2011 10:03 PM, Tom Z wrote: >>> We do not know what skin you use, we will assume that you use >>> Xenomai posix skin, so, compile with the right flags. >> >> Here is how I >> build my program, say, fooTest: gcc -I/usr/xenomai/include >> -D_GNU_SOURCE -D_REENTRANT -Wall -pipe -D__XENO__ -lnative >> -L/usr/xenomai/lib -lxenomai -lpthread -lnative -lrtdk fooTest.c -o >> fooTest > > You are using the native skin then. > >>> CLOCK_PROCESS_CPUTIME_ID is not implemented for xenomai posix skin, >>> so, clock_gettime probably returns an error, and the struct timespec >>> is unchanged. If somehow the glibc clock_gettime is used, and this >>> call does not cause a system call, then all bets are off, and even a >>> lockup could happen. >> >> Thanks for explaining this. So can I trust the >> CPU time I obtained with my method when the function is running in >> the primary mode? It seems you explanation implies that the results I >> obtained are not reliable, if so, are there other reliable ways to >> obtain the CPU time? > > No, CLOCK_PROCESS_CPUTIME is a clock implemented by the Linux kernel, > so, it does not see the time spent in primary mode. If the foo function > does not suspend, you can use rt_timer_tsc(), but the answer is no, > there is currently no way to get the cpu time used when in primary mode. > There is one, but deeply buried in the API basement, via rt_task_inquire(): RT_TASK_INFO info; RTIME start; ret = rt_task_inquire(NULL, &info); /* NULL means current task */ if (ret) goto Houston_handles_the_problem; start = info.exectime; ... do work .... ret = rt_task_inquire(NULL, &info); delta = info.exectime - start; /* elapsed CPU time in ns */ rt_task_inquire() will beget a syscall each time invoked though, so it does have some overhead. You need CONFIG_XENO_OPT_STATS enabled in your Kconfig for this feature (defaults to on). -- Philippe. From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4EB53B0C.7060303@domain.hid> Date: Sat, 05 Nov 2011 14:33:00 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <1320433713.81220.YahooMailNeo@domain.hid> <4EB43B3E.806@domain.hid> <1320440601.64091.YahooMailNeo@domain.hid> <4EB45AF6.60304@domain.hid> <1320460319.56312.YahooMailNeo@domain.hid> In-Reply-To: <1320460319.56312.YahooMailNeo@domain.hid> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-help] 0 CPU time problem List-Id: Help regarding installation and common use of Xenomai List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Tom Z Cc: "xenomai@xenomai.org" On 11/05/2011 03:31 AM, Tom Z wrote: > Hi Gilles, > > > No, CLOCK_PROCESS_CPUTIME is a clock implemented by the Linux > > kernel, so, it does not see the time spent in primary mode. If the > > foo function does not suspend, you can use rt_timer_tsc(), but the > > answer is no, there is currently no way to get the cpu time used > > when in primary mode. > > Thanks a lot for the explanation. It seems my understanding on how > Xenomai works was incorrect. I thought that if a task, say, > myRTTask() is spawned by rt_task_create() and rt_task_start(), then > myRTTask() will always run in the primary mode, so if myRTTask() > calls foo(), then foo() will be running in the primary mode all the > time. The correct fact is, myRTTask() could be running in either the > primary mode or the secondary mode, right? This arises my another > question, if foo() uses some third party libraries (with source code > available), how can I tell what parts of foo() will be running in the > primary mode, and what parts will be in the secondary mode? Are there > principles for deciding whether the code is in the primary mode or > the secondary mode? Hi, it would be nice if you could quote and wrap mails as is usual on public mailing lists. Every Linux system call causes a switch to secondary mode, as well as every call to a xenomai system call documented as such. For instance, if you look at rt_queue_create documentation, you see: Environments: This service can be called from: * Kernel module initialization/cleanup code * User-space task (switches to secondary mode) If you want to detect unwanted mode switches to secondary mode, you can use rt_task_set_mode with the T_WARNSW bit, as is demonstrated in the example: examples/native/sigdebug.c in xenomai sources tree. -- Gilles.