Philippe Vaucher wrote:
I haven't tried it but according to various links, GetSystemTime() only gives ~10ms or ~15ms precision
Thank you for the links!
Some results looks bizarre tho, like timeGetTime() at the same level than GetTickCount() seems quite weird to me. The graphs also seems to indicate QPC has one of the largest call overhead, would it be a concern ?
Anyway, this makes me wonder what is the rational behind using GetSystemTimeAsFileTime() to implement date_time::microsec_clock ? Does anyone know (or could an author entlighten us) ?
Sorry to be so quiet...it's not that I'm not interested, just too busy to really contribute. Anyway, the reason for GetSystemTimeAsFileTime is that it works. And it doesn't suffer from the rollover issue and the stability issues that the QPC stuff does in the face of multi-threading. So it just works and it gives enough precision for 90% of the applications.
This also raise another question, if we chose to implement microsec_timer with QPC, what will we name the timer implemented with posix_time::microsec_clock (which is just a typedef for date_time::microsec_clock) ?
I'll be happy to replace the current microsec_clock implementation as long as you can deal with rollover and multi-threading. Oh, and you can't add any data members to the ptime which might expand it's size. And since the microsec_clock is all static there could be some complications if you need to store data to handle rollover. QPC based implementation been discussed for years, but I've never seen anyone actually implement something that works as reliably as GetSystemTimeAsFileTime.... Jeff