On Thu, 3 Jan 2013, Alexander Motin wrote:
On 03.01.2013 16:45, Bruce Evans wrote:
On Wed, 2 Jan 2013, Alexander Motin wrote:
More important for scheduling fairness thread's CPU percentage is also
based on hardclock() and hiding from it was trivial before, since all
sleep primitives were strictly aligned to hardclock(). Now it is
slightly less trivial, since this alignment was removed and user-level
APIs provide no easy way to enforce it.
%cpu is actually based on statclock(), and not even used for scheduling.
May be for SCHED_4BSD, but not for SCHED_ULE. In SCHED_ULE both %cpu and
thread priority based on the same ts_ticks counter, that is based on
hardclock() as time source. Interactivity calculation uses alike logic and
uses the same time source.
Hmm. I missed this because it hacks on the 'ticks' global. It is clearer
in intermediate versions which use the scheduler API sched_tick(), which
is the hardclock analogue of sched_clock() for statclock. sched_tick() is
now bogus since it is null for all schedulers.
Bruce
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