linux-kernel - [tip:sched/core] sched/cpuacct: Show all possible CPUs in cpuacct output

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Message-ID: <tip-5ca3726af7f66a8cc71ce4414cfeb86deb784491@git.kernel.org>
Date:	Thu, 31 Mar 2016 02:27:16 -0700
From:	tip-bot for Zhao Lei <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	efault@....de, tglx@...utronix.de, torvalds@...ux-foundation.org,
	zhaolei@...fujitsu.com, htejun@...il.com, hpa@...or.com,
	peterz@...radead.org, mingo@...nel.org,
	linux-kernel@...r.kernel.org
Subject: [tip:sched/core] sched/cpuacct: Show all possible CPUs in cpuacct
 output

Commit-ID:  5ca3726af7f66a8cc71ce4414cfeb86deb784491
Gitweb:     http://git.kernel.org/tip/5ca3726af7f66a8cc71ce4414cfeb86deb784491
Author:     Zhao Lei <zhaolei@...fujitsu.com>
AuthorDate: Tue, 22 Mar 2016 16:37:07 +0800
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 31 Mar 2016 10:45:56 +0200

sched/cpuacct: Show all possible CPUs in cpuacct output

Current code show stats of online CPUs in cpuacct.statcpus,
show stats of present cpus in cpuacct.usage(_percpu), and using
present CPUs for setting cpuacct.usage.

It will cause inconsistent result when a CPU is online or offline
or hotpluged.

We should always use possible CPUs to avoid above problem.

Here are the contents of a cpuacct.usage_percpu sysfs file,
on a 4 CPU system with maxcpus=32:

Before the patch:
 # cat cpuacct.usage_percpu
 2456565 411435 1052897 832584

After the patch:
 # cat cpuacct.usage_percpu
 2456565 411435 1052897 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Zhao Lei <zhaolei@...fujitsu.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mike Galbraith <efault@....de>
Cc: Tejun Heo <htejun@...il.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/a11d56cef12d0b4807f8be3a46bf9798c3014d59.1458635566.git.zhaolei@cn.fujitsu.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/cpuacct.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index 4a81120..e39bd4f 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -138,7 +138,7 @@ static u64 cpuusage_read(struct cgroup_subsys_state *css, struct cftype *cft)
 	u64 totalcpuusage = 0;
 	int i;
 
-	for_each_present_cpu(i)
+	for_each_possible_cpu(i)
 		totalcpuusage += cpuacct_cpuusage_read(ca, i);
 
 	return totalcpuusage;
@@ -159,7 +159,7 @@ static int cpuusage_write(struct cgroup_subsys_state *css, struct cftype *cft,
 		goto out;
 	}
 
-	for_each_present_cpu(i)
+	for_each_possible_cpu(i)
 		cpuacct_cpuusage_write(ca, i, 0);
 
 out:
@@ -172,7 +172,7 @@ static int cpuacct_percpu_seq_show(struct seq_file *m, void *V)
 	u64 percpu;
 	int i;
 
-	for_each_present_cpu(i) {
+	for_each_possible_cpu(i) {
 		percpu = cpuacct_cpuusage_read(ca, i);
 		seq_printf(m, "%llu ", (unsigned long long) percpu);
 	}
@@ -191,7 +191,7 @@ static int cpuacct_stats_show(struct seq_file *sf, void *v)
 	int cpu;
 	s64 val = 0;
 
-	for_each_online_cpu(cpu) {
+	for_each_possible_cpu(cpu) {
 		struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu);
 		val += kcpustat->cpustat[CPUTIME_USER];
 		val += kcpustat->cpustat[CPUTIME_NICE];
@@ -200,7 +200,7 @@ static int cpuacct_stats_show(struct seq_file *sf, void *v)
 	seq_printf(sf, "%s %lld\n", cpuacct_stat_desc[CPUACCT_STAT_USER], val);
 
 	val = 0;
-	for_each_online_cpu(cpu) {
+	for_each_possible_cpu(cpu) {
 		struct kernel_cpustat *kcpustat = per_cpu_ptr(ca->cpustat, cpu);
 		val += kcpustat->cpustat[CPUTIME_SYSTEM];
 		val += kcpustat->cpustat[CPUTIME_IRQ];