threads and their time slots. [modified]

[Souldrift]

One last thought. I just tried to not let the thread sleep or create a wait object or anything. I simply went into a while-loop. Endlessly. Where I fetched and printed the system time. This was the result

RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781458000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781614000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781614000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781614000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781614000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781614000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781614000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781614000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781614000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781614000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781614000.000000, send time = 12891115378155.598000.
RTPEngine: Time now = 128911153781614000.000000

[Stuart Dootson]

Souldrift wrote:

And so on ... it always jumps 15,6ms forward

Here's what Mark Russinovitch and David Solomon say in Windows Internals

_

On Windows 2000 Professional and Windows XP, threads run by default for 2 clock intervals; on Windows Server systems, by default, a thread runs for 12 clock intervals. The rationale for the longer default value on server systems is to minimize context switching. By having a longer quantum, server applications that wake up as the result of a client request have a better chance of completing the request and going back into a wait state before their quantum ends

The length of the clock interval varies according to the hardware platform. The frequency of the clock interrupts is up to the HAL, not the kernel. For example, the clock interval for most x86 uniprocessors is about 10 milliseconds and for most x86 multiprocessors it is about 15 milliseconds. (The actual clock rate is not exactly a round number of milliseconds—see the following experiment for a way to check the actual clock interval.)

EXPERIMENT: Determining the Clock Interval Frequency

The Windows GetSystemTimeAdjustment function returns the clock interval. To determine the clock interval, download and run the Clockres program[^] from http://www.sysinternals.com.

_

That kind of confirms what you're seeing (and what I see - which is 15.625, or 500/32). HOWEVER!!!! I steered you wrong with waitable timers. I mistook them for a TimerQueueTimer in my memory. Try this:

#include <Windows.h>
#include <tchar.h>
#include <iostream>

void ReportTime(const char* message, LONGLONG const& when)
{
std::cout << message << double(when)/10000.0 << std::endl;
}

LONG count;
LARGE_INTEGER liStart, liEnd, liFreq;

VOID CALLBACK DoSendHere(__in_opt LPVOID lpArgToCompletionRoutine,
__in DWORD dwTimerLowValue,
__in DWORD dwTimerHighValue)
{
QueryPerformanceCounter(&liEnd);
count++;
}

void SendLoop()
{
HANDLE hTimerQueue = CreateTimerQueue();
HANDLE hTimer;
count = 0;
CreateTimerQueueTimer(&hTimer, hTimerQueue, (WAITORTIMERCALLBACK)&DoSendHere, 0 , 1, 1, WT_EXECU

[Roger Stoltz]

Souldrift wrote:

it always jumps 15,6ms forward

I doubt the granularity and accuracy of the time value returned by ::GetSystemTimeAsFileTime(). Even though the FILETIME structure is a time value where the least significant bit represents 100 nanoseconds, it doesn't mean that it has an accuracy of 100 nanosecs. It's like looking at your watch, measuring a time with the needle showing seconds and then multiplying the value by 1,000,000 and claim you measured with microsecond accuracy. For time measurements of this kind you should you the performance timer; ::QueryPerformanceCounter() and ::QueryPerformanceFrequency(). It will give you the best accuracy available on your hardware. Read here[^] for more info on the high resolution performance counter.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

[Roger Stoltz]

Bah, you beat me to it... :-\

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

[Stuart Dootson]

Sorrreeeee :-O

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

[Roger Stoltz]

:laugh:

"It's supposed to be hard, otherwise anybody could do it!" - selfquote
"High speed never compensates for wrong direction!" - unknown

[Souldrift]

Uhh, thanks, I´ll try that out in a moment. Thanks for the writings on Windows Internals. Who could have known such a thing :). Very interesting. Two things, though. Why do you set a sleep time of 65ms (instead of infinite)? And I don´t see why this should circumvent the 15ms time-slice. QueryPerformanceCounter might 'see' higher resolution, but if the thread sleeps for 15ms, there´s nothing to see? Or is there? Souldrift

[Stuart Dootson]

The 65ms is just an example time - it can't be infinite because I want it to terminate :-) The thing that's seeing past the 15.625 timer resolution is the TimerQueueTimer. That has a resolution of 1ms. The program is intended to show that the timer callback is called with a resolution of 1ms, so could be used in your case, so long as your thread can remain the active thread.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

[Souldrift]

Okay, I thought so (after some thinking). Now if you will bear with me one more time, I´m not quite sure how to understand (handle) this regarding my case. For example if I use this (cause 9ms are appx. the time I need to wait before sending)

CreateTimerQueueTimer(&hTimer, hTimerQueue, (WAITORTIMERCALLBACK)&DoSendHere, 0 , 9, 1, WT_EXECUTEINTIMERTHREAD);
QueryPerformanceCounter(&liStart);
::SleepEx(65, TRUE);

The callback func should with a 65ms sleep be called like 7 times. Though my log shows 54. I guess, this is because the timer doesn´t stop after my sleep or my sending. So the next question would be, how do I stop it? I know, i doesn´t even have to be periodic for what I need (so it would stop by itself), but I´m trying to understand the structure. I added a DeleteTimerQueueEx( hTimerQueue, NULL ); but it crashes now at that point. Souldrift Edit: And why does it not call the callback func when I take away the sleepEx()?? Is it dependant on the thread being asleep? If I do this

CreateTimerQueueTimer(&hTimer, hTimerQueue, (WAITORTIMERCALLBACK)&DoSendHere, 0 , 1, 0, WT_EXECUTEINTIMERTHREAD);
QueryPerformanceCounter(&liStart);
::SleepEx(10, TRUE);

it doesn´t enter, either.

modified on Monday, July 6, 2009 4:32 AM

[Stuart Dootson]

Souldrift wrote:

CreateTimerQueueTimer(&hTimer, hTimerQueue, (WAITORTIMERCALLBACK)&DoSendHere, 0 , 9, 1, WT_EXECUTEINTIMERTHREAD);

You're asking for a timer with an initial delay of 9ms and periodic delays after that of 1ms.

Souldrift wrote:

DeleteTimerQueueEx( hTimerQueue, NULL );

Think that should be DeleteTimerQueueTimer( hTimerQueue, hTimer, 0 );. That worked for me, anyway.

Souldrift wrote:

And why does it not call the callback func when I take away the sleepEx()?? Is it dependant on the thread being asleep?

The thread needs to be in an alertable state - look at the MSDN documentation[^] for what that means.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p