Messages in this thread | | | Date | Sat, 7 Mar 2015 10:22:15 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 02/12] clocksource: Simplify logic around clocksource wrapping saftey margins |
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* John Stultz <john.stultz@linaro.org> wrote:
> The clocksource logic has a number of places where we try to > include a safety margin. Most of these are 12% safety margins, > but they are inconsistently applied and sometimes are applied > on top of each other. > > Additionally, in the previous patch, we corrected an issue > where we unintentionally in effect created a 50% saftey margin, > which these 12.5% margins where then added to. > > So to siplify the logic here, this patch removes the various
Typo.
> 12.5% margins, and consolidates adding the margin in one place: > clocks_calc_max_nsecs(). > > Addtionally, Linus prefers a 50% safety margin, as it allows > bad clock values to be more easily caught. This should really > have no net effect, due to the corrected issue earlier which > caused greater then 50% margins to be used w/o issue. > > Cc: Dave Jones <davej@codemonkey.org.uk> > Cc: Linus Torvalds <torvalds@linux-foundation.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Richard Cochran <richardcochran@gmail.com> > Cc: Prarit Bhargava <prarit@redhat.com> > Cc: Stephen Boyd <sboyd@codeaurora.org> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Acked-by: Stephen Boyd <sboyd@codeaurora.org> (for sched_clock.c bit) > Signed-off-by: John Stultz <john.stultz@linaro.org> > --- > kernel/time/clocksource.c | 26 ++++++++++++-------------- > kernel/time/sched_clock.c | 4 ++-- > 2 files changed, 14 insertions(+), 16 deletions(-) > > diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c > index 11323f4..e5d00e6 100644 > --- a/kernel/time/clocksource.c > +++ b/kernel/time/clocksource.c > @@ -469,6 +469,9 @@ static u32 clocksource_max_adjustment(struct clocksource *cs) > * @shift: cycle to nanosecond divisor (power of two) > * @maxadj: maximum adjustment value to mult (~11%) > * @mask: bitmask for two's complement subtraction of non 64 bit counters > + * > + * NOTE: This function includes a saftey margin of 50%, so that bad clock values
Typo.
There's also the same typo in the title of the patch.
Thanks,
Ingo
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