Hi Vincent,
On 10/9/14, 10:18 PM, Vincent Guittot wrote:
On 9 October 2014 14:16, Peter Zijlstra <pet...@infradead.org> wrote:
On Tue, Oct 07, 2014 at 02:13:36PM +0200, Vincent Guittot wrote:
+static inline bool
+group_has_capacity(struct lb_env *env, struct sg_lb_stats *sgs)
{
+ if ((sgs->group_capacity * 100) >
+ (sgs->group_usage * env->sd->imbalance_pct))
+ return true;
Why the imb_pct there? We're looking for 100% utilization, not 130 or
whatnot, right?
Having exactly 100% is quite difficult because of various rounding.
Could you give some examples about the various rounding？
Regards,
Wanpeng Li
So i have added a margin/threshold to prevent any excessive change of the state.
I have just to use the same margin/threshold than in other place in
load balance.
so the current threshold depends of the sched_level. it's around 14% at MC level
+ if (sgs->sum_nr_running < sgs->group_weight)
+ return true;
With the code as it stands, this is the cheaper test (no mults) so why
is it second?
+ return false;
+}
+static inline bool
+group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs)
+{
+ if (sgs->sum_nr_running <= sgs->group_weight)
+ return false;
+
+ if ((sgs->group_capacity * 100) <
+ (sgs->group_usage * env->sd->imbalance_pct))
+ return true;
+ return false;
}
Same thing here wrt imb_pct
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