Net cpu usage of pthreads?!

mynickmynick · 09-23-2008, 03:56 AM

Measuring gross and net cpu usage of pthreads? From one point of the code to another (not average like calling ps)

i can measure gross cpu usage by reading special Pentium registers like for instance using opencv functions cvGetTickCount() and cvGetTickFrequency()

i can measure net cpu usage by all threads (one process) by using clock()

But I don't have currently available functions to measure net cpu usage by one single thread!!

matsp · 09-23-2008, 04:00 AM

Quote:

Originally Posted by mynickmynick

Measuring gross and net cpu usage of pthreads? From one point of the code to another (not average like calling ps)

i can measure gross cpu usage by reading special Pentium registers like for instance using opencv functions cvGetTickCount() and cvGetTickFrequency()

i can measure net cpu usage by all threads (one process) by using clock()

But I don't have currently available functions to measure net cpu usage by one single thread!!

And part of that is because threads are not accounted separately in the Linux kernel, if I remember correctly. Search the forum for "Thread CPU time" and I'm sure there's another thread where this was discussed, and some sort of hacky solution was found, IIRC.

mynickmynick · 09-23-2008, 05:54 AM

i did not find what i need
it's strange

matsp · 09-23-2008, 06:49 AM

I'm sure I've worked on this before, but one of your threads have a comment:
time measure (net and gross) with pthreads under linux

--
Mats

Codeplug · 09-23-2008, 07:57 AM

More info: http://www.linuxforums.org/forum/lin...cess-time.html

gg

mynickmynick · 09-25-2008, 03:10 AM

Quote:

Originally Posted by Codeplug

More info: http://www.linuxforums.org/forum/lin...cess-time.html

gg

excellent
this seems what i was looking for

mynickmynick · 09-25-2008, 03:47 AM

But unfortunately I found that the required
#define _POSIX_THREAD_CPUTIME 0
is 0 in my system so the function clock_gettime () is not supported for a call like

Code:

#include <time.h>
#include <unistd.h> // for sysconf
int err;
struct timespec t;
if (sysconf(_POSIX_THREAD_CPUTIME)){
  err = clock_gettime(CLOCK_THREAD_CPUTIME_ID,&t);
}

mynickmynick · 09-25-2008, 03:51 AM

but the header posix_opt.h says:

Code:

/* Clock support in threads must be also checked at runtime.  */
#define _POSIX_THREAD_CPUTIME	0

so how can i check it run time?

matsp · 09-25-2008, 03:56 AM

Check the return value, it will return some sort of error saying "not supported" if it's not supported, one would assume.

--
Mats

mynickmynick · 09-25-2008, 03:57 AM

Quote:

Originally Posted by matsp

Check the return value, it will return some sort of error saying "not supported" if it's not supported, one would assume.

--
Mats

yes sorry I misread
sysconf() checks for availability
But I don't understand why it should be checked at run time??

matsp · 09-25-2008, 04:09 AM

Quote:

Originally Posted by mynickmynick

yes sorry I misread
sysconf() checks for availability
But I don't understand why it should be checked at run time??

Becuase, presumably, it can be configured in or out of any particular OS - I don't KNOW the reason, but it makes sense that the reason that you can't know at compile time is that some OS's support it and others don't.

--
Mats

mynickmynick · 09-25-2008, 07:31 AM

Quote:

Originally Posted by Codeplug

More info: http://www.linuxforums.org/forum/lin...cess-time.html

gg

Unfortunately I tried clock_gettime(CLOCK_THREAD_CPUTIME_ID,t); and I found out that it gives a gross value (time elapsed include time used by other threads!!)

Codeplug · 09-25-2008, 10:23 AM

>> I found out that it gives a gross value (time elapsed include time used by other threads!!)
How did you confirm that?

You could also compare the value with what's in /proc/<PID>/task/<TID>/stat, for Linux 2.6 and up.

gg

mynickmynick · 09-26-2008, 01:48 AM

Quote:

Originally Posted by Codeplug

>> I found out that it gives a gross value (time elapsed include time used by other threads!!)
How did you confirm that?

You could also compare the value with what's in /proc/<PID>/task/<TID>/stat, for Linux 2.6 and up.

gg

I have debian with kernel 2.6.18
one main thread
one station thread
two camera threads
(several other threads not measured, but basically idle)
the measure given was always the same for all threads (except some difference due to different termination instant) and the same as the value given by Open CV pentium clock measure
So despite what said the measure is per process not per thread

mynickmynick · 09-26-2008, 01:49 AM

Still Looking!! Please other suggestions!!
ps with special options gives a net per thread cpu usage so this info should be vailable with some special functions at kernel level??

09-23-2008, 03:56 AM	#1
mynickmynick Alessio Stella Join Date: May 2008 Location: Italy, Bologna Posts: 235	Net cpu usage of pthreads?! Measuring gross and net cpu usage of pthreads? From one point of the code to another (not average like calling ps) i can measure gross cpu usage by reading special Pentium registers like for instance using opencv functions cvGetTickCount() and cvGetTickFrequency() i can measure net cpu usage by all threads (one process) by using clock() But I don't have currently available functions to measure net cpu usage by one single thread!!
mynickmynick is offline

09-23-2008, 05:54 AM	#3
mynickmynick Alessio Stella Join Date: May 2008 Location: Italy, Bologna Posts: 235	i did not find what i need it's strange
mynickmynick is offline

09-23-2008, 06:49 AM	#4
matsp Kernel hacker Join Date: Jul 2007 Location: Farncombe, Surrey, England Posts: 15,686	I'm sure I've worked on this before, but one of your threads have a comment: time measure (net and gross) with pthreads under linux -- Mats __________________ Compilers can produce warnings - make the compiler programmers happy: Use them! Please don't PM me for help - and no, I don't do help over instant messengers.
matsp is offline

09-23-2008, 07:57 AM	#5
Codeplug Registered User Join Date: Mar 2003 Posts: 3,844	More info: http://www.linuxforums.org/forum/lin...cess-time.html gg
Codeplug is offline

09-25-2008, 03:47 AM	#7
mynickmynick Alessio Stella Join Date: May 2008 Location: Italy, Bologna Posts: 235	But unfortunately I found that the required #define _POSIX_THREAD_CPUTIME 0 is 0 in my system so the function clock_gettime () is not supported for a call like Code: #include <time.h> #include <unistd.h> // for sysconf int err; struct timespec t; if (sysconf(_POSIX_THREAD_CPUTIME)){ err = clock_gettime(CLOCK_THREAD_CPUTIME_ID,&t); }
mynickmynick is offline

09-25-2008, 03:51 AM	#8
mynickmynick Alessio Stella Join Date: May 2008 Location: Italy, Bologna Posts: 235	but the header posix_opt.h says: Code: /* Clock support in threads must be also checked at runtime. */ #define _POSIX_THREAD_CPUTIME 0 so how can i check it run time?
mynickmynick is offline

09-25-2008, 03:56 AM	#9
matsp Kernel hacker Join Date: Jul 2007 Location: Farncombe, Surrey, England Posts: 15,686	Check the return value, it will return some sort of error saying "not supported" if it's not supported, one would assume. -- Mats __________________ Compilers can produce warnings - make the compiler programmers happy: Use them! Please don't PM me for help - and no, I don't do help over instant messengers.
matsp is offline

09-25-2008, 10:23 AM	#13
Codeplug Registered User Join Date: Mar 2003 Posts: 3,844	>> I found out that it gives a gross value (time elapsed include time used by other threads!!) How did you confirm that? You could also compare the value with what's in /proc/<PID>/task/<TID>/stat, for Linux 2.6 and up. gg
Codeplug is offline

09-26-2008, 01:49 AM	#15
mynickmynick Alessio Stella Join Date: May 2008 Location: Italy, Bologna Posts: 235	Still Looking!! Please other suggestions!! ps with special options gives a net per thread cpu usage so this info should be vailable with some special functions at kernel level??
mynickmynick is offline

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