QueryPerformanceCounter failure

Hi,

I'm getting an error while calling QueryPerformanceCounter and I don't know why.

Code:

---

LARGE_INTEGER start;
BOOL bRet = QueryPerformanceCounter(&start);

ASSERT(bRet);
if(FALSE == bRet)
{
  int nError = GetLastError();
  PrintError(nError);
}

---

The function returns FALSE, meaning it failed, but when I call GetLastError() it returns 0, meaning ERROR_SUCCES; there was no error... :confused:

However If I do this, it works just fine:

Code:

---

LARGE_INTEGER* start = new LARGE_INTEGER;
BOOL bRet = QueryPerformanceCounter(start);

ASSERT(bRet);
if(FALSE == bRet)
{
  int nError = GetLastError();
  PrintError(nError);
}

delete start;

---

LARGE_INTEGER looks like this:

Code:

---

typedef union union
{ 
  struct
  {   
    DWORD LowPart;   
    LONG HighPart; 
  }; 
  LONGLONG QuadPart;
} LARGE_INTEGER, *PLARGE_INTEGER;

---

I'm working on WinXP, with VC6.0, SP6, and have an AthlonXP 1600+.

Why is the first code failing (with 0 returned by GetErrorSucces) and the second one is just ok?

Thanks.

I forgot to mention that I'm doing this in a multi-thread MDI application. I cannot post it here, it has more than 200,000 code lines and it ain't worth to isolate just that part.

I tried to create another simple (MDI) application, put there the code and it works beautiful. So, it makes me wonder even more... :confused: :sick:

cilu, are you sure that problem is in multithreading? AFAIR QueryPerformanceCounter() is thread-safe function, so may be there are another circumstances?

I didn't say that the problem is multi-threading, I just wanted to give as much details as possible. The code posted is taken from a member function of a CDocument derived class.

Quote:

---

Originally Posted by cilu

Hi,

I'm getting an error while calling QueryPerformanceCounter and I don't know why.

Code:

---

LARGE_INTEGER start;
BOOL bRet = QueryPerformanceCounter(&start);

ASSERT(bRet);
if(FALSE == bRet)
{
  int nError = GetLastError();
  PrintError(nError);
}

---

The function returns FALSE, meaning it failed, but when I call GetLastError() it returns 0, meaning ERROR_SUCCES; there was no error... :confused:

---

I just had the same problem but I notice something else:
- If the variable is a member of the class: The function fails.
- If the variable is a pointer (allocated with a new): The function works.
- If the variable is local (on the stack): The function works.

So my workaround is the following:

Code:

---

LARGE_INTEGER start;
BOOL bRet = QueryPerformanceCounter(&start);

ASSERT(bRet);
if(FALSE == bRet)
{
  int nError = GetLastError();
  PrintError(nError);
}
else
{
  m_start = start;
}

---

Thanks for your post, it helps me to find a solution. :)

Regards.

For what it's worth it looks like QueryPerformanceCounter is sensitive to the argument alignment. specifically the structure needs to be 4 bytes aligned on my hardware.
I stepped onto the similar problem while working with byte aligned data (pragma pack 1). Make sure you arguments are at least 4 bytes aligned.

Cheers.