linux-kernel - [PATCH v11 9/9] cpuset: Allow reporting of sched domain generation info

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Date:   Sun, 24 Jun 2018 15:30:40 +0800
From:   Waiman Long <longman@...hat.com>
To:     Tejun Heo <tj@...nel.org>, Li Zefan <lizefan@...wei.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>
Cc:     cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, kernel-team@...com, pjt@...gle.com,
        luto@...capital.net, Mike Galbraith <efault@....de>,
        torvalds@...ux-foundation.org, Roman Gushchin <guro@...com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Waiman Long <longman@...hat.com>
Subject: [PATCH v11 9/9] cpuset: Allow reporting of sched domain generation info

This patch enables us to report sched domain generation information.

If DYNAMIC_DEBUG is enabled, issuing the following command

  echo "file cpuset.c +p" > /sys/kernel/debug/dynamic_debug/control

and setting loglevel to 8 will allow the kernel to show what scheduling
domain changes are being made.

Signed-off-by: Waiman Long <longman@...hat.com>
---
 kernel/cgroup/cpuset.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 07a5575..62b7e61 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -836,6 +836,23 @@ static int generate_sched_domains(cpumask_var_t **domains,
 	return ndoms;
 }
 
+#ifdef CONFIG_DEBUG_KERNEL
+static inline void debug_print_domains(cpumask_var_t *doms, int ndoms)
+{
+	int i;
+	char buf[200];
+	char *ptr, *end = buf + sizeof(buf) - 1;
+
+	for (i = 0, ptr = buf, *end = '\0'; i < ndoms; i++)
+		ptr += snprintf(ptr, end - ptr, "dom%d=%*pbl ", i,
+				cpumask_pr_args(doms[i]));
+
+	pr_debug("Generated %d domains: %s\n", ndoms, buf);
+}
+#else
+static inline void debug_print_domains(cpumask_var_t *doms, int ndoms) { }
+#endif
+
 /*
  * Rebuild scheduler domains.
  *
@@ -871,6 +888,7 @@ static void rebuild_sched_domains_locked(void)
 
 	/* Generate domain masks and attrs */
 	ndoms = generate_sched_domains(&doms, &attr);
+	debug_print_domains(doms, ndoms);
 
 	/* Have scheduler rebuild the domains */
 	partition_sched_domains(ndoms, doms, attr);
-- 
1.8.3.1