[tip:sched/core] sched, timer: Provide an atomic ' struct task_cputime' data structure

[tip-bot for Jason Low <tipbot@zytor.com>]

Commit-ID:  971e8a985482c76487edb5a49811e99b96e846e1
Gitweb:     http://git.kernel.org/tip/971e8a985482c76487edb5a49811e99b96e846e1
Author:     Jason Low <jason.low2@hp.com>
AuthorDate: Tue, 28 Apr 2015 13:00:23 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 8 May 2015 12:17:45 +0200

sched, timer: Provide an atomic 'struct task_cputime' data structure

This patch adds an atomic variant of the 'struct task_cputime' data structure,
which can be used to store and update task_cputime statistics without
needing to do locking.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Jason Low <jason.low2@hp.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aswin Chandramouleeswaran <aswin@hp.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Scott J Norton <scott.norton@hp.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Waiman Long <Waiman.Long@hp.com>
Link: http://lkml.kernel.org/r/1430251224-5764-5-git-send-email-jason.low2@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 include/linux/sched.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index a45874c..6eb78cd 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -572,6 +572,23 @@ struct task_cputime {
 		.sum_exec_runtime = 0,				\
 	}
 
+/*
+ * This is the atomic variant of task_cputime, which can be used for
+ * storing and updating task_cputime statistics without locking.
+ */
+struct task_cputime_atomic {
+	atomic64_t utime;
+	atomic64_t stime;
+	atomic64_t sum_exec_runtime;
+};
+
+#define INIT_CPUTIME_ATOMIC \
+	(struct task_cputime_atomic) {				\
+		.utime = ATOMIC64_INIT(0),			\
+		.stime = ATOMIC64_INIT(0),			\
+		.sum_exec_runtime = ATOMIC64_INIT(0),		\
+	}
+
 #ifdef CONFIG_PREEMPT_COUNT
 #define PREEMPT_DISABLED	(1 + PREEMPT_ENABLED)
 #else