clock skew with 1000Hz kernels

[bleomycin]

Hello everyone, i have been running 1000Hz kernels in every variation for several months now (currently on 2.6.30.1) and one problem i have not been able to tackle is the increase in clock skew with running at 1000Hz. The system seems to gain about half a second a day compared to another machine with a stock kernel updated with ntp before comparing. I am not running RT patches anymore, im not sure if RT, with it's hrtimer's would improve this or not? Running NTP caused nothing but issues with srcds, although i wonder if increasing the interval at which ntp is updated would help? Thanks!

[css]

Did you run ntp from cron or as daemon? Running as daemon should be quite safe, because then ntpd adjusts the clock in quite small intervals. It doesn't change the clock immediately to the correct value but changes it in small steps.

Chaning clock can cause problems with srcds. I've experienced that if the clock jumps backwards like one hour (hehe, after daylight savings) then the server freezes. It happens probably because all the interpolation calculations go hey-hey and then divide by zero happens

[bleomycin]

css Wrote:Did you run ntp from cron or as daemon? Running as daemon should be quite safe, because then ntpd adjusts the clock in quite small intervals. It doesn't change the clock immediately to the correct value but changes it in small steps.

Chaning clock can cause problems with srcds. I've experienced that if the clock jumps backwards like one hour (hehe, after daylight savings) then the server freezes. It happens probably because all the interpolation calculations go hey-hey and then divide by zero happens

Yes i did have ntp running as a daemon, and when it was running srcds logs would be full of errors about the time being changed back by 1 second and whatnot, and this was generally accompanied by a short world freeze in TF2, although not always. My concern isn't so much what time the game server thinks it is, for all i care it could think its in 1969, its just that with these 1000Hz kernels it seems to keep less accurate time. The fact that it has a less accurate idea of exactly how long 1 second is could be affecting gameplay?

[css]

Do you know if the clock is skewed with 100 Hz kernel too?

Maybe you should just follow BehaartesEtwas' instructions at http://wiki.fragaholics.de/index.php/EN:Linux_Kernel_Optimization and use RT patches too (as instructed).