summaryrefslogtreecommitdiffstats
path: root/src/corelib/kernel/qelapsedtimer.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'src/corelib/kernel/qelapsedtimer.cpp')
-rw-r--r--src/corelib/kernel/qelapsedtimer.cpp27
1 files changed, 3 insertions, 24 deletions
diff --git a/src/corelib/kernel/qelapsedtimer.cpp b/src/corelib/kernel/qelapsedtimer.cpp
index 57825583dd..3bfb1f15ec 100644
--- a/src/corelib/kernel/qelapsedtimer.cpp
+++ b/src/corelib/kernel/qelapsedtimer.cpp
@@ -139,9 +139,9 @@ QT_BEGIN_NAMESPACE
\value SystemTime The human-readable system time. This clock is not monotonic.
\value MonotonicClock The system's monotonic clock, usually found in Unix systems. This clock is monotonic and does not overflow.
- \value TickCounter The system's tick counter, used on Windows systems. This clock may overflow.
+ \value TickCounter Not used anymore.
\value MachAbsoluteTime The Mach kernel's absolute time (\macos and iOS). This clock is monotonic and does not overflow.
- \value PerformanceCounter The high-resolution performance counter provided by Windows. This clock is monotonic and does not overflow.
+ \value PerformanceCounter The performance counter provided by Windows. This clock is monotonic and does not overflow.
\section2 SystemTime
@@ -161,24 +161,6 @@ QT_BEGIN_NAMESPACE
This clock does not overflow.
- \section2 TickCounter
-
- The tick counter clock type is based on the system's or the processor's
- tick counter, multiplied by the duration of a tick. This clock type is
- used on Windows platforms. If the high-precision performance
- counter is available on Windows, the \tt{PerformanceCounter} clock type
- is used instead.
-
- The TickCounter clock type is the only clock type that may overflow.
- Windows Vista and Windows Server 2008 support the extended 64-bit tick
- counter, which allows avoiding the overflow.
-
- On Windows systems, the clock overflows after 2^32 milliseconds, which
- corresponds to roughly 49.7 days. This means two processes' reckoning of
- the time since the reference may be different by multiples of 2^32
- milliseconds. When comparing such values, it's recommended that the high
- 32 bits of the millisecond count be masked off.
-
\section2 MachAbsoluteTime
This clock type is based on the absolute time presented by Mach kernels,
@@ -192,10 +174,7 @@ QT_BEGIN_NAMESPACE
\section2 PerformanceCounter
This clock uses the Windows functions \tt{QueryPerformanceCounter} and
- \tt{QueryPerformanceFrequency} to access the system's high-precision
- performance counter. Since this counter may not be available on all
- systems, QElapsedTimer will fall back to the \tt{TickCounter} clock
- automatically, if this clock cannot be used.
+ \tt{QueryPerformanceFrequency} to access the system's performance counter.
This clock is monotonic and does not overflow.