sched-proc-sched_debug-fails-on-very-very-large-machines-v2

v2: Took suggetion for adding comments

Signed-off-by: Nathan Zimmer <nzimmer@sgi.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 25be2dd939a5f4d371e2f1e29229b54f1cbbdf81..1ed4c2dca389ed1081dbb43c1c0ef1ec820ff1ae 100644 (file)
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -406,6 +406,13 @@ void sysrq_sched_debug_show(void)
 
 }
 
+/*
+ * This itererator needs some explination.
+ * It returns 1 for the header position.
+ * This means 2 is cpu 0.
+ * In a hotplugged system some cpus, including cpu 0, may be missing so we have
+ * to use cpumask_* to iterate over the cpus.
+ */
 static void *sched_debug_start(struct seq_file *file, loff_t *offset)
 {
        unsigned long n = *offset;