For i386 with TSC, the kernel calibrates how much CPU cycles will fit between two timer interrupts. That value corresponds to 10000 microseconds. Ideally. In practice however the timer interrupts do not happen exactly every 10000 us (for hardware reasons). When interpolating time between ticks that calibration value is used. When using NTP (or adjusting tick manually) the value added every tick may be different from 10000us. If that value is larger, the time seems to jump ahead at the beginning of each tick; if the value is smaller, the time may seem to get stuck, get slow, or jump back at the beginning of a new tick. Therefore I added experimental code to scale the value used for tick interpolation according to these corrections. As it seems to me, the clock quality improves, and the performance penalty only appears when the correction value changes. I haven't done the non-TSC case or other architectures. For microseconds it may seem neglectible, but not for nanoseconds. If anybody has an interesting opinion on this, please Mail. Regards, Ulrich P.S. Not subscribed here. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
