[ntp:questions] ntp daemon wakeup/sleep patch by RedHat

Hal Murray hal-usenet at ip-64-139-1-69.sjc.megapath.net
Wed Jun 13 21:36:05 UTC 2007

In article <001501c7adf1$81109660$0a00a8c0 at Inspiron>,
 jason at extremeoverclocking.com (Jason Rabel) writes:

>NTP Power Consuming? Compared to what? I run a 300MHz Geode based NTP box
>and hardly see *any* CPU usage at all (0.01 maybe?). That machine consumes
>maybe 10W of power... 15W peak if I'm compiling stuff.

The target is clients rather than servers.  Consider a battery
powered laptop.  A lot of work has gone into this area recently.

I don't have hard numbers and they will depend upon what you
are doing, but doubling battery time would be my ballpark sort of
guess.  You can probably get much better than that is some
interesting cases.

One idea is to turn off the CPU between keystrokes and packets.
(DRAM does self refresh.)  Not idle/sleep, but off, as in remove
the power.

It takes 10-100 ms (handwave) to power up and go back to sleep.
Idle loops that wakeup every second but don't do anything useful
can use a lot of battery.

There is probably a mechanism to synchronize that sort of loop
when it is really needed.  All N jobs get to run with one power up
cycle rather than bouncing on/off N times.

I haven't looked at the code yet.  If it looks reasonable, I'd
encourage folding it into the main codebase.

These are my opinions, not necessarily my employer's.  I hate spam.

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