Re: [PATCH v6 04/16] sched/core: uclamp: Add CPU's clamp buckets refcounting
From: Peter Zijlstra <peterz@infradead.org>
Date: 2019-01-21 15:17:29
Also in:
linux-pm, lkml
On Tue, Jan 15, 2019 at 10:15:01AM +0000, Patrick Bellasi wrote:
+#ifdef CONFIG_UCLAMP_TASK
+struct uclamp_bucket {
+ unsigned long value : bits_per(SCHED_CAPACITY_SCALE);
+ unsigned long tasks : BITS_PER_LONG - bits_per(SCHED_CAPACITY_SCALE);
+};+struct uclamp_cpu {
+ unsigned int value;/* 4 byte hole */
+ struct uclamp_bucket bucket[UCLAMP_BUCKETS]; +};
With the default of 5, this UCLAMP_BUCKETS := 6, so struct uclamp_cpu ends up being 7 'unsigned long's, or 56 bytes on 64bit (with a 4 byte hole).
quoted hunk ↗ jump to hunk
+#endif /* CONFIG_UCLAMP_TASK */ + /* * This is the main, per-CPU runqueue data structure. *@@ -835,6 +879,11 @@ struct rq { unsigned long nr_load_updates; u64 nr_switches; +#ifdef CONFIG_UCLAMP_TASK + /* Utilization clamp values based on CPU's RUNNABLE tasks */ + struct uclamp_cpu uclamp[UCLAMP_CNT] ____cacheline_aligned;
Which makes this 112 bytes with 8 bytes in 2 holes, which is short of 2 64 byte cachelines. Is that the best layout?
+#endif + struct cfs_rq cfs; struct rt_rq rt; struct dl_rq dl; -- 2.19.2