Maxima......not being heated at all, just wanted to make sure I was very clear for everyone about what I have found out recently with NT + DTN. No......Gomi was not the trader, but I am sure he also has everything well sorted out since he is a very good programmer!
Each PC contains two clocks: "hardware clock" and the "software clock." The software clock runs when the PC is turned on and stops when the PC is turned off. The hardware clock uses a backup battery and continues to run even when the PC is turned off. An Intel 8254 timer-counter (or functionally equivalent device) generates the software clock. This timer-counter generates an interrupt every 54.936 milliseconds, or about 18.2 times per second. The PC BIOS (basic input output system) contains a software routine that counts the interrupt requests and generates a time-of-day clock that can be read or set by other software programs. For example, the operating system might use the time-of-day information from the software clock to date and stamp files. The software clock is a poor timekeeper. Any change in the interrupt-request rates causes the clock to gain or lose time. If the PC is left on for long periods of time, the software clock can be off by large amounts. A minute or more per day that the PC was left on is not an uncommon error rate. It is also possible for an ill-behaved software program to use the timer-counter for another purpose and change the interrupt rate. This could cause the software clock to rapidly gain or lose time. The hardware clock is either a separate real-time clock or a RTC function integrated into the PC's chipset. The hardware clock is updated once per second and does not resolve to fractions of a second. Its timing accuracy is determined by the quality of the crystal oscillator it uses as its time base. A typical crystal has an initial frequency error of greater than ±20ppm, which will translate to greater than ±1.7 seconds per day. In actual operation, with temperature effects included, most hardware clocks gain or lose 5 to 15 seconds per day. As you can see, neither the software nor the hardware PC clock is suitable as an accurate timekeeping reference. For higher time keeping reference systems sync to internet time servers using NTP protocol - RFC-1305. The time servers provides a data packet that includes a 64-bit time stamp containing the time in UTC seconds since January 1, 1900, with a resolution of 200 picoseconds. NTP provides accuracy of 1 to 50 milliseconds. NTP client software normally runs continuously and gets periodic updates from three or more independent servers. The graph shows my server's system clock is +/- 50ms even when constantly synced to three independent ntp servers and CME's Time servers.
Thank you for the thorough explanation. Now that makes sense... I have one more question if you dont mind... How would you explain the relation of the IC clock deviations to the OS ? Could be it simply an erroneus measurement tool (the one which produce graphs) ? How Windows affects work of the cheapset? Could it be a bad driver? Just to explain - I am trying to understand this for myself, no sarcasm, how come Windows deviates 100ms in just 3hr and I didnt know about it... Just personal thing you know...
Other O/S's have NTP time referencing built in. Windows out of the box does not... But we are just talking system time. There are other high frequency system timers which are used to time specific processes.
PocketChange, What software you use for updating time ? I used Dimension 4 when running XP , under Vista it doesn't work
obviously guys is talking about high-end enterprise server solutions... It is as if you ask a guy who services/designes Ferrary engines - what oil do you use mate, my cousin sells discounted Shell smuggled from Russian oil plant... It's Dr. Evil, I didn't spend six years in Evil Medical School to be called "mister," thank you very much.
Ironic I can use D4 on Win 7, which is Vista based, never used Vista so I never experienced that problem.
Here what he said earlier : "Check out meinberg.de and http://www.time-server-monitor.com" HTH P.S. as long as I know there are plenty of cheap and expensive hardware clock synchronisers... This is a whole industry with long history.. Not only trading concerns. Just google it.... if you are so preoccupied with cuckoo business
I am a loss to understand what clock drift on a PC has to do with incorrect bid/ask transacted volume. As long as the incoming stream is buffered the event sequence should be preserved even if the absolute time stamp is a bit off a bit of clock drift shouldn't have any significant effect. A TCP connection provides a fair bit of buffering (and flow control) without application software needing to worry about it. Operating system TCP buffer size should be tunable - it's a long time since I looked at this so I forget the details. Of course keeping your clock synchronized via NTP is a good idea. You will get clock drift on Linux systems too, BTW. There are real time Linux kernels that may better - I'm not sure.