> I have built the executable for ARM cortex A8 NEON processor and profiling the
>  code using the momentics ICE 6.4.1 and the target board.
> 
> 1. Whether the profiling is accurate ?
> 2. Does the profiling also includes the context switching time while executing
>  any process ?
> 3. How to get accurate time (i.e. only time taken taken to run each function 
> excluding system overheads and context switching time etc) for any function ?

from within Momentics build options there are two different types of profiling available.
-classical gnu gprof style profiling
-function instrumentation profiling
to get detailed information you have to use the "function insturmentation" option.

to be abale to do threaded accounting you have to work together with kernel tracing.
normal logging in shared mem file does not provide the information about scheduling.
in other words: if you have one instrumented thread, the numbers will not be accurate according to other threads 
runnings
t1: P1.T1(instr) -> foo() enter
t2: scheduler
t3: Px.Tx -> running for x time
t4: scheduler
t5: P1.T1(instr) -> foo() exit
accounting will give you t5 - t1 as execution time for foo() and you do not see the scheduling.

about accuracy: be aware of Heisenberg, using function insturmentation and kernel tarcing you'll get a high system 
impact so that you should only look at the % numbers (and there was some stuff with inlines not being inlined any more).


have you allready checked this:
http://www.qnx.com/developers/docs/6.4.1/ide_en/user_guide/profiler.html

HTH
/hp

There are few profiling methods to consider depends on your systems, for 
simplicity we give users two choices:
sampling + call count instrumentation
or function instrumentation

If you do function instrumentation you have also two choice: system-wide 
and single app.

The answer depends on what method you using.

Sampling require long running up, it is statistical method. It will only 
count sample if process is running (i.e. if it is blocked it won't be 
counted). Limitation: cannot use on multi-core cpu unless all threads 
are bound to cpu 0

Function Instrumentation in single app mode - counts elapsed time (in 
6.4.1), i.e. no context switches considered, also it is not good for 
multiple threads app if all threads are active. Profiling overhead is 
removed from final data.

Function Instrumentation in system-wide mode, same as above if you using 
App Profiler tool, but you also can use System Profiler tool - where you 
see non-aggregated data,
including context switches, and you can see statistics data for threads 
states, and so on.
It is very precise but generates lots of data, so you cannot really 
profiler more than a minute in this mode.

If you give me more details on your scenario I can recommend one method 
over the other.

Girisha SG wrote:
> I have built the executable for ARM cortex A8 NEON processor and profiling the code using the momentics ICE 6.4.1 and 
the target board.
>
> 1. Whether the profiling is accurate ?
> 2. Does the profiling also includes the context switching time while executing any process ?
> 3. How to get accurate time (i.e. only time taken taken to run each function excluding system overheads and context 
switching time etc) for any function ?
>
>
>
> _______________________________________________
>
> General
> http://community.qnx.com/sf/go/post61320
>
>