On Wed, Sep 23, 2015 at 02:15:51PM +0800, Chao Yu wrote: > div_u64 can only handle 32-bits divisor, if our divisor is with type of > 64-bits, we should use div64_u64 instead, otherwise value of divisor will > be cast to 32-bits, resulting in wrong calculation. > > Signed-off-by: Chao Yu <[email protected]> > --- > kernel/sched/fair.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 9176f7c..ee268ef 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -6086,7 +6086,7 @@ static unsigned long scale_rt_capacity(int cpu) > > total = sched_avg_period() + delta; > > - used = div_u64(avg, total); > + used = div64_u64(avg, total);
total here should not exceed 2*sched_avg_period() 'much', with the defaults this would end up being around 1e9. So unless you prod at sysctl_sched_time_avg it should all work out fine with the 32bit divisor. Have you seen problems here? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
