On May 18, 12:39 am, [EMAIL PROTECTED] (Danny Mayer) wrote: > > It's not doing nothing. If the CPU is on standby nothing, including > ntpd, should be running.
One thing is the CPU in standby, something else the whole system. In modern x86 systems running Linux, the CPU enters C1 state when there's no task to run. When the CPU is in the C1 state, the internal circuitry is shutdown, reducing the power used by the by about one order of magnitude. Some processors will automatically enter deeper CPU standby states, others require OS intervention. Linux will use all available CPU standby states as often as possible by default. So even after a few fractions of a second in the C1 state, it can put the CPU in C2 (or C3) state, when the processor disconnects the core from the bus interface keeping caches coherent (or not), reducing the power to a fraction of the C1 state. Amazingly enough, servers spend most of the time in a C state, whether waiting for disk access or for network replies. Therefore, it's a critical part of power management in data-center. In data-centers, every W used by equipment will require another W in AC. With several systems, it's not difficult to end up with a few kWh everyday due to NTP, which translates into possibly hundreds of dollars in additional costs. HTH _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
