linux-kernel - [PATCH 02/15] sched: make nr_iowait

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Message-Id: <20200420205743.19964-2-adobriyan@gmail.com>
Date:   Mon, 20 Apr 2020 23:57:30 +0300
From:   Alexey Dobriyan <adobriyan@...il.com>
To:     akpm@...ux-foundation.org
Cc:     adobriyan@...il.com, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, pmladek@...e.com,
        rostedt@...dmis.org, sergey.senozhatsky@...il.com,
        andriy.shevchenko@...ux.intel.com, linux@...musvillemoes.dk
Subject: [PATCH 02/15] sched: make nr_iowait_cpu() return "unsigned int"

Same logic: 2^32 threads stuck waiting in runqueue implies
2^32+ processes total which is absurd.

Per-runqueue ->nr_iowait member being 32-bit hints that it is
correct change!

Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
---
 drivers/cpuidle/governors/menu.c | 6 +++---
 fs/proc/stat.c                   | 2 +-
 include/linux/sched/stat.h       | 4 ++--
 kernel/sched/core.c              | 6 +++---
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index b0a7ad566081..ddaaa36af290 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -117,7 +117,7 @@ struct menu_device {
 	int		interval_ptr;
 };
 
-static inline int which_bucket(u64 duration_ns, unsigned long nr_iowaiters)
+static inline int which_bucket(u64 duration_ns, unsigned int nr_iowaiters)
 {
 	int bucket = 0;
 
@@ -150,7 +150,7 @@ static inline int which_bucket(u64 duration_ns, unsigned long nr_iowaiters)
  * to be, the higher this multiplier, and thus the higher
  * the barrier to go to an expensive C state.
  */
-static inline int performance_multiplier(unsigned long nr_iowaiters)
+static inline int performance_multiplier(unsigned int nr_iowaiters)
 {
 	/* for IO wait tasks (per cpu!) we add 10x each */
 	return 1 + 10 * nr_iowaiters;
@@ -270,7 +270,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev,
 	unsigned int predicted_us;
 	u64 predicted_ns;
 	u64 interactivity_req;
-	unsigned long nr_iowaiters;
+	unsigned int nr_iowaiters;
 	ktime_t delta_next;
 	int i, idx;
 
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 93ce344f62a5..678feb7b9949 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -198,7 +198,7 @@ static int show_stat(struct seq_file *p, void *v)
 		"btime %llu\n"
 		"processes %lu\n"
 		"procs_running %u\n"
-		"procs_blocked %lu\n",
+		"procs_blocked %u\n",
 		nr_context_switches(),
 		(unsigned long long)boottime.tv_sec,
 		total_forks,
diff --git a/include/linux/sched/stat.h b/include/linux/sched/stat.h
index f3b86515bafe..c4bd2fc95219 100644
--- a/include/linux/sched/stat.h
+++ b/include/linux/sched/stat.h
@@ -18,8 +18,8 @@ DECLARE_PER_CPU(unsigned long, process_counts);
 extern int nr_processes(void);
 unsigned int nr_running(void);
 extern bool single_task_running(void);
-extern unsigned long nr_iowait(void);
-extern unsigned long nr_iowait_cpu(int cpu);
+unsigned int nr_iowait(void);
+unsigned int nr_iowait_cpu(int cpu);
 
 static inline int sched_info_on(void)
 {
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d9bae602966c..ec98244e9d96 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3428,7 +3428,7 @@ unsigned long long nr_context_switches(void)
  * it does become runnable.
  */
 
-unsigned long nr_iowait_cpu(int cpu)
+unsigned int nr_iowait_cpu(int cpu)
 {
 	return atomic_read(&cpu_rq(cpu)->nr_iowait);
 }
@@ -3463,9 +3463,9 @@ unsigned long nr_iowait_cpu(int cpu)
  * Task CPU affinities can make all that even more 'interesting'.
  */
 
-unsigned long nr_iowait(void)
+unsigned int nr_iowait(void)
 {
-	unsigned long i, sum = 0;
+	unsigned int i, sum = 0;
 
 	for_each_possible_cpu(i)
 		sum += nr_iowait_cpu(i);
-- 
2.24.1