sched: fix task_h_load()
Currently task_h_load() computes the load of a task and uses that to either
subtract it from the total, or add to it.
However, removing or adding a task need not have any effect on the total load
at all. Imagine adding a task to a group that is local to one cpu - in that
case the total load of that cpu is unaffected.
So properly compute addition/removal:
s_i = S * rw_i / \Sum_j rw_j
s'_i = S * (rw_i + wl) / (\Sum_j rw_j + wg)
then s'_i - s_i gives the change in load.
Where s_i is the shares for cpu i, S the group weight, rw_i the runqueue weight
for that cpu, wl the weight we add (subtract) and wg the weight contribution to
the runqueue.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 734e4c5..a169444 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1074,22 +1074,53 @@
static const struct sched_class fair_sched_class;
#ifdef CONFIG_FAIR_GROUP_SCHED
-static unsigned long task_h_load(struct task_struct *p)
+static unsigned long effective_load(struct task_group *tg, long wl, int cpu)
{
- unsigned long h_load = p->se.load.weight;
- struct cfs_rq *cfs_rq = cfs_rq_of(&p->se);
+ struct sched_entity *se = tg->se[cpu];
+ long wg = wl;
- update_h_load(task_cpu(p));
+ for_each_sched_entity(se) {
+#define D(n) (likely(n) ? (n) : 1)
- h_load = calc_delta_mine(h_load, cfs_rq->h_load, &cfs_rq->load);
+ long S, Srw, rw, s, sn;
- return h_load;
+ S = se->my_q->tg->shares;
+ s = se->my_q->shares;
+ rw = se->my_q->load.weight;
+
+ Srw = S * rw / D(s);
+ sn = S * (rw + wl) / D(Srw + wg);
+
+ wl = sn - s;
+ wg = 0;
+#undef D
+ }
+
+ return wl;
}
+
+static unsigned long task_load_sub(struct task_struct *p)
+{
+ return effective_load(task_group(p), -(long)p->se.load.weight, task_cpu(p));
+}
+
+static unsigned long task_load_add(struct task_struct *p, int cpu)
+{
+ return effective_load(task_group(p), p->se.load.weight, cpu);
+}
+
#else
-static unsigned long task_h_load(struct task_struct *p)
+
+static unsigned long task_load_sub(struct task_struct *p)
+{
+ return -p->se.load.weight;
+}
+
+static unsigned long task_load_add(struct task_struct *p, int cpu)
{
return p->se.load.weight;
}
+
#endif
static int
@@ -1112,9 +1143,9 @@
* of the current CPU:
*/
if (sync)
- tl -= task_h_load(current);
+ tl += task_load_sub(current);
- balanced = 100*(tl + task_h_load(p)) <= imbalance*load;
+ balanced = 100*(tl + task_load_add(p, this_cpu)) <= imbalance*load;
/*
* If the currently running task will sleep within