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Jul 6th, 2009

Re: How to get a thread's execution time

When you spawn the thread you pass a void user value!
Why not pass a boolean pointer! Loop while it is set and when false fall out of the thread loop. Don't forget your thread exit function for proper cleanup.

C++ Syntax (Toggle Plain Text)
void MyWorker( void *foo )
{
    bool *pbSignal = (bool *)foo;
 
   while (foo)
   {
 
 
   }
 
}
void MyWorker( void *foo )
{
    bool *pbSignal = (bool *)foo;

   while (foo)
   {


   }

}

Or pass in a local index for that worker thread.

C++ Syntax (Toggle Plain Text)
void MyWorker( void *foo )
{
    uint idx = (uint)foo;
 
   while ( gbAppActive == true )
   {
 
 
   }
 
   gThreadActive[ idx ] = false;  // Tell root that this thread is shut down
 
}
void MyWorker( void *foo )
{
    uint idx = (uint)foo;

   while ( gbAppActive == true )
   {


   }

   gThreadActive[ idx ] = false;  // Tell root that this thread is shut down

}

In application root cleanup.
Loop for up until all gThreadActive[] become clear or the clock runs out, whichever comes first.

If you use semaphores, use a single gThreadActive parameter and merely clear the bit!

C++ Syntax (Toggle Plain Text)
LOCK();
gThreadActive ^= 1 << idx;
UNLOCK();
LOCK();
gThreadActive ^= 1 << idx;
UNLOCK();

wildgoose

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Jul 7th, 2009

Re: How to get a thread's execution time

Quote ...

When you spawn the thread you pass a void user value!
Why not pass a boolean pointer!

When you spawn the thread you pass a void pointer, which means you pass a pointer to something (or nothing). I am already using this to pass some arguments to the threads.
Wildgoose, I don't get what this last post has to offer to the discussion.

rmlopes

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Jul 7th, 2009

Re: How to get a thread's execution time

I don't understand what's so difficult about thread timing. If you want the thread to quit after a specified amount of time, then just compare current time with original thread entry time and exit when that difference is greater than some pre-determined amount of time.

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Jul 7th, 2009

Re: How to get a thread's execution time

Click to Expand / Collapse Quote originally posted by Ancient Dragon ...

I don't understand what's so difficult about thread timing. If you want the thread to quit after a specified amount of time, then just compare current time with original thread entry time and exit when that difference is greater than some pre-determined amount of time.

I don't understand what's so difficult about multi-threading for you. Threads yield execution to other threads and gain it back and yield again... etc. When they yeld they are not running anymore so any "raw" difference between starting time and current time is *not* what you want. Stop insisting please... I would flag your last post as a bad post...

NOTE: as mentioned in a previous post this issue can be solved in UNIX by using clock_gettime with the flag CLOCK_THREAD_CPUTIME_ID. I don't even need to save the start point because each thread's clock is set to 0 when it starts. I made the tests, 10 threads executing for 50 seconds in a core-duo processor, giving total time ~= 250 seconds, perfect for me!
I am still looking for a solution which can be applied cross-platform, or at least a similar solution for windows.

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Jul 7th, 2009

Re: How to get a thread's execution time

GetThreadTimes()

I have not used it and don't know if it will meet your needs. Did you overlook this thread?

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Jul 7th, 2009

Re: How to get a thread's execution time

Thanks, this looks like what I want for windows. As soon as I have tried it, I will post comments on it.

rmlopes

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Jan 10th, 2011

Function to get thread CPU usage

BOOL WINAPI GetThreadTimes(
__in HANDLE hThread,
__out LPFILETIME lpCreationTime,
__out LPFILETIME lpExitTime,
__out LPFILETIME lpKernelTime,
__out LPFILETIME lpUserTime
);

http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx

It is only updated on context switch so a Sleep(1) is needed before calling it. THERE ARE OTHER CAVEATS so that it may not be suitable for measuring very small increments.

IMPORTANT CAVEATS here!

http://blog.kalmbachnet.de/?postid=28

Vista provides

BOOL WINAPI QueryThreadCycleTime(
__in HANDLE ThreadHandle,
__out PULONG64 CycleTime
);

http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx

I don't know what caveats apply to this call.

JohnDiego

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Jan 11th, 2011

Re: How to get a thread's execution time

C++ Syntax (Toggle Plain Text)
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
 
void thread_function( void* arg )
{
   time_t   start, finish;
   long loop;
   double   result, elapsed_time;
 
   time( &start );
 
   // Your thread code
 
   time( &finish );
 
   elapsed_time = difftime( finish, start );
   printf( "\nThread takes %6.0f seconds.\n", elapsed_time );
}
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void thread_function( void* arg )
{
   time_t   start, finish;
   long loop;
   double   result, elapsed_time;
  
   time( &start );
    
   // Your thread code

   time( &finish );

   elapsed_time = difftime( finish, start );
   printf( "\nThread takes %6.0f seconds.\n", elapsed_time );
}

The code counts for the execution time of one thread, it doesn't matter if the thread is active or not.

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Jan 31st, 2011

One more caveat

I did some testing on this. As suggested in other posts, these aren't all that accurate, they tend to run low due to the thread accounting, context switches, etc. They are much more useful to locate long-running piggy threads.

QueryPerformanceCounter is the way to go, or RDTSC, both as noted here. QPC uses RDTSC, with some code around it to make sure the value is reasonable.

http://en.wikipedia.org/wiki/Time_Stamp_Counter

The Performance counter is very high res, you don't need to run something 10,000 times. Unless it is really short you can measure it directly. Just watch for context switches in the middle of the measurement. Those will be obvious because the elapsed time will jump to milliseconds and beyond. I routinely measure code timing.

Click to Expand / Collapse Quote originally posted by JohnDiego ...

BOOL WINAPI GetThreadTimes(
__in HANDLE hThread,
__out LPFILETIME lpCreationTime,
__out LPFILETIME lpExitTime,
__out LPFILETIME lpKernelTime,
__out LPFILETIME lpUserTime
);

http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx

It is only updated on context switch so a Sleep(1) is needed before calling it. THERE ARE OTHER CAVEATS so that it may not be suitable for measuring very small increments.

IMPORTANT CAVEATS here!

http://blog.kalmbachnet.de/?postid=28

Vista provides

BOOL WINAPI QueryThreadCycleTime(
__in HANDLE ThreadHandle,
__out PULONG64 CycleTime
);

http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx

I don't know what caveats apply to this call.

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