Re: measuring elapsed time on mingw

[Bruno Haible]

Hi Eric,

> >   - QueryPerformanceCounter [1] has a resolution of 0.5 ms or higher.
> 
> ... if you use it, then you run into the issues of file timestamp mismatch
> (cygwin currently has a known issue where, because it uses
> QueryPerformanceCounter instead of GetSystemTimeAsFileTime for
> implementing utimensat(UTIME_NOW), a file can not only appear newer than
> what a corresponding file system operation would be, but also time can
> appear to travel backwards when following a utimensat(UTIME_NOW)
> operation by a normal file system operation).

This matches the difficulties that are described in [1]. But I would think
the difficulties come in only when you try to combine the
GetSystemTimeAsFileTime and QueryPerformanceCounter results? When you use
only QueryPerformanceCounter, you should be fine (except for [2])?

Bruno

[1] http://msdn.microsoft.com/en-us/magazine/cc163996.aspx
[2] http://support.microsoft.com/kb/274323/en-us/