On Wed, Mar 13, 2019 at 03:59:54PM +0000, Patrick Bellasi wrote:

On 13-Mar 14:52, Peter Zijlstra wrote:

quoted

quoted

+static inline void uclamp_rq_dec_id(struct task_struct *p, struct rq *rq,
+				    unsigned int clamp_id)
+{
+	unsigned int bucket_id = p->uclamp[clamp_id].bucket_id;
+	unsigned int rq_clamp, bkt_clamp;
+
+	SCHED_WARN_ON(!rq->uclamp[clamp_id].bucket[bucket_id].tasks);
+	if (likely(rq->uclamp[clamp_id].bucket[bucket_id].tasks))
+		rq->uclamp[clamp_id].bucket[bucket_id].tasks--;
+
+	/*
+	 * Keep "local clamping" simple and accept to (possibly) overboost
+	 * still RUNNABLE tasks in the same bucket.
+	 */
+	if (likely(rq->uclamp[clamp_id].bucket[bucket_id].tasks))
+		return;

(Oh man, I hope that generates semi sane code; long live CSE passes I
suppose)

What do you mean ?

that does: 'rq->uclamp[clamp_id].bucket[bucket_id].tasks' three times in
a row. And yes the compiler _should_ dtrt, but....