On Mon, May 12, 2014 at 08:12:45PM +0200, Sven Barth wrote: > On 12.05.2014 15:33, Michael Schnell wrote: > >On 05/12/2014 02:47 PM, Reinier Olislagers wrote: > >>Do you mean direct access to the hardware bypassing the OS? I > >>thought that wasn't possible in Windows? > > > >I don't know how the dynamic library call in Windows works. > > If in doubt, take a look at ReactOS ;) > > QueryPerformanceCounter calls NtQueryPerformanceCounter (which is a > system call), which in turn calls KeQueryPerformanceCounter (which is > implemented by the Hardware Abstraction Layer) which is defined here > at around line 250: > http://svn.reactos.org/svn/reactos/trunk/reactos/hal/halx86/generic/timer.c?revision=58489&view=markup
On linux, glibc (and others) will route gettimeofday() (and clock_gettime() for certain clock IDs) via vDSO and no syscall will be called, so it's very fast. I don't think the fpc rtl does this, though? More info in the vdso man page for which functions are supported for which architectures. Henry -- _______________________________________________ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus