linux-kernel - [PATCH 2/3] cgroup/rstat: Cleanup cpu.stat once for all

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Message-Id: <20250123174713.25570-3-wuyun.abel@bytedance.com>
Date: Fri, 24 Jan 2025 01:47:02 +0800
From: Abel Wu <wuyun.abel@...edance.com>
To: Tejun Heo <tj@...nel.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Koutný <mkoutny@...e.com>,
	Jonathan Corbet <corbet@....net>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Abel Wu <wuyun.abel@...edance.com>,
	Bitao Hu <yaoma@...ux.alibaba.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Yury Norov <yury.norov@...il.com>,
	Chen Ridong <chenridong@...wei.com>
Cc: cgroups@...r.kernel.org (open list:CONTROL GROUP (CGROUP)),
	linux-doc@...r.kernel.org (open list:DOCUMENTATION),
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 2/3] cgroup/rstat: Cleanup cpu.stat once for all

There were efforts like b824766504e4 ("cgroup/rstat: add force idle show helper")
to escape from #ifdef hells, and there could be new stats coming out in
the future, let's clean it up once for all.

Signed-off-by: Abel Wu <wuyun.abel@...edance.com>
---
 kernel/cgroup/rstat.c | 46 +++++++++++++++++++++++--------------------
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index c2784c317cdd..6ad647f3e241 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -599,21 +599,38 @@ static void root_cgroup_cputime(struct cgroup_base_stat *bstat)
 	}
 }
 
+static struct bstat_entry {
+	const char	*name;
+	const int	offset;
+} bstats[] = {
+#define BSTAT_ENTRY(name, field)	\
+	{ name, offsetof(struct cgroup_base_stat, field) }
+	BSTAT_ENTRY("usage_usec",	cputime.sum_exec_runtime),
+	BSTAT_ENTRY("user_usec",	cputime.utime),
+	BSTAT_ENTRY("system_usec",	cputime.stime),
+	BSTAT_ENTRY("nice_usec",	ntime),
+#ifdef CONFIG_SCHED_CORE
+	BSTAT_ENTRY("core_sched.force_idle_usec", forceidle_sum),
+#endif
+	{ NULL } /* must be at end */
+#undef BSTAT_ENTRY
+};
 
-static void cgroup_force_idle_show(struct seq_file *seq, struct cgroup_base_stat *bstat)
+static void __append_bstat(struct seq_file *seq, struct cgroup_base_stat *bstat,
+			   struct bstat_entry *entry)
 {
-#ifdef CONFIG_SCHED_CORE
-	u64 forceidle_time = bstat->forceidle_sum;
+	u64 *val;
 
-	do_div(forceidle_time, NSEC_PER_USEC);
-	seq_printf(seq, "core_sched.force_idle_usec %llu\n", forceidle_time);
-#endif
+	val = (void *)bstat + entry->offset;
+	do_div(*val, NSEC_PER_USEC);
+	seq_printf(seq, "%s %llu\n", entry->name, *val);
 }
 
 void cgroup_base_stat_cputime_show(struct seq_file *seq)
 {
 	struct cgroup *cgrp = seq_css(seq)->cgroup;
 	struct cgroup_base_stat bstat;
+	struct bstat_entry *e;
 
 	if (cgroup_parent(cgrp)) {
 		cgroup_rstat_flush_hold(cgrp);
@@ -625,21 +642,8 @@ void cgroup_base_stat_cputime_show(struct seq_file *seq)
 		root_cgroup_cputime(&bstat);
 	}
 
-	do_div(bstat.cputime.sum_exec_runtime, NSEC_PER_USEC);
-	do_div(bstat.cputime.utime, NSEC_PER_USEC);
-	do_div(bstat.cputime.stime, NSEC_PER_USEC);
-	do_div(bstat.ntime, NSEC_PER_USEC);
-
-	seq_printf(seq, "usage_usec %llu\n"
-			"user_usec %llu\n"
-			"system_usec %llu\n"
-			"nice_usec %llu\n",
-			bstat.cputime.sum_exec_runtime,
-			bstat.cputime.utime,
-			bstat.cputime.stime,
-			bstat.ntime);
-
-	cgroup_force_idle_show(seq, &bstat);
+	for (e = bstats; e->name; e++)
+		__append_bstat(seq, &bstat, e);
 }
 
 /* Add bpf kfuncs for cgroup_rstat_updated() and cgroup_rstat_flush() */
-- 
2.37.3