linux-kernel - [PATCH v7 1/2] nohz: add tick_nohz_full_add_cpus_to() and _remove_cpus

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Message-ID: <1428699232-7940-1-git-send-email-cmetcalf@ezchip.com>
Date:	Fri, 10 Apr 2015 16:53:51 -0400
From:	Chris Metcalf <cmetcalf@...hip.com>
To:	"Peter Zijlstra (Intel)" <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Ingo Molnar <mingo@...hat.com>, <linux-kernel@...r.kernel.org>
CC:	Chris Metcalf <cmetcalf@...hip.com>
Subject: [PATCH v7 1/2] nohz: add tick_nohz_full_add_cpus_to() and _remove_cpus_from() APIs

The "removes_cpus_from" API is useful, for example, to modify a cpumask
to avoid the nohz cores so that interrupts aren't sent to them.

Likewise the "add_cpus_to" API is useful to modify a cpumask indicating
some special nohz-type functionality so that the nohz cores are
automatically added to that set.

Signed-off-by: Chris Metcalf <cmetcalf@...hip.com>
---
v7: no change here, just in part 2/2.

v6: I think we may finally have accessor names that are OK

v5: (skipped this patch)

v4: update accessor names to make them clearer [PeterZ]

v3: no change here, just in part 2/2.

v2: put the "...set_cpus" API together with the change to
init_sched_domains() so that they can go into the timer tree
independently of other changes in my tree.

 include/linux/tick.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

 include/linux/tick.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/include/linux/tick.h b/include/linux/tick.h
index 9c085dc12ae9..8d1754c0f694 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -186,6 +186,18 @@ static inline bool tick_nohz_full_cpu(int cpu)
 	return cpumask_test_cpu(cpu, tick_nohz_full_mask);
 }
 
+static inline void tick_nohz_full_add_cpus_to(struct cpumask *mask)
+{
+	if (tick_nohz_full_enabled())
+		cpumask_or(mask, mask, tick_nohz_full_mask);
+}
+
+static inline void tick_nohz_full_remove_cpus_from(struct cpumask *mask)
+{
+	if (tick_nohz_full_enabled())
+		cpumask_andnot(mask, mask, tick_nohz_full_mask);
+}
+
 extern void __tick_nohz_full_check(void);
 extern void tick_nohz_full_kick(void);
 extern void tick_nohz_full_kick_cpu(int cpu);
@@ -194,6 +206,8 @@ extern void __tick_nohz_task_switch(struct task_struct *tsk);
 #else
 static inline bool tick_nohz_full_enabled(void) { return false; }
 static inline bool tick_nohz_full_cpu(int cpu) { return false; }
+static inline void tick_nohz_full_add_cpus_to(struct cpumask *mask) { }
+static inline void tick_nohz_full_remove_cpus_from(struct cpumask *mask) { }
 static inline void __tick_nohz_full_check(void) { }
 static inline void tick_nohz_full_kick_cpu(int cpu) { }
 static inline void tick_nohz_full_kick(void) { }
-- 
2.1.2

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