Re: VM Report was:Re: Break 2.4 VM in five easy steps

[Mark Hahn]

> reads the RTC device.  The patched RTC driver can then
> measure the elapsed time between the interrupt and the
> read from userspace.  Voila: latency.

interesting, but I'm not sure there's much advantage over
doing it entirely in user-space with the normal /dev/rtc:

        http://brain.mcmaster.ca/~hahn/realfeel.c

it just prints out the raw time difference from when
rtc should have woken up the program.  you can do your own histogram;
for summary purposes, something like stdev is probably best.

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