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Message-Id: <20191125094618.30298-2-parth@linux.ibm.com>
Date: Mon, 25 Nov 2019 15:16:16 +0530
From: Parth Shah <parth@...ux.ibm.com>
To: linux-kernel@...r.kernel.org
Cc: peterz@...radead.org, mingo@...hat.com, vincent.guittot@...aro.org,
patrick.bellasi@...bug.net, valentin.schneider@....com,
qais.yousef@....com, pavel@....cz, dhaval.giani@...cle.com,
qperret@...rret.net, David.Laight@...LAB.COM,
morten.rasmussen@....com, pjt@...gle.com, tj@...nel.org,
dietmar.eggemann@....com, viresh.kumar@...aro.org,
rafael.j.wysocki@...el.com, daniel.lezcano@...aro.org
Subject: [RFC 1/3] Introduce latency-tolerance as an per-task attribute
Latency-tolerance indicates the latency requirements of a task with respect
to the other tasks in the system. The value of the attribute can be within
the range of [-20, 19] both inclusive to be in-line with the values just
like task nice values.
latency_tolerance = -20 indicates the task to have the least latency as
compared to the tasks having latency_tolerance = +19.
The latency_tolerance may affect only the CFS SCHED_CLASS by getting
latency requirements from the userspace.
Signed-off-by: Parth Shah <parth@...ux.ibm.com>
---
include/linux/sched.h | 3 +++
include/linux/sched/latency_tolerance.h | 13 +++++++++++++
2 files changed, 16 insertions(+)
create mode 100644 include/linux/sched/latency_tolerance.h
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 2c2e56bd8913..bcc1c1d0856d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -25,6 +25,7 @@
#include <linux/resource.h>
#include <linux/latencytop.h>
#include <linux/sched/prio.h>
+#include <linux/sched/latency_tolerance.h>
#include <linux/sched/types.h>
#include <linux/signal_types.h>
#include <linux/mm_types_task.h>
@@ -666,6 +667,8 @@ struct task_struct {
#endif
int on_rq;
+ int latency_tolerance;
+
int prio;
int static_prio;
int normal_prio;
diff --git a/include/linux/sched/latency_tolerance.h b/include/linux/sched/latency_tolerance.h
new file mode 100644
index 000000000000..7a00abe05bc4
--- /dev/null
+++ b/include/linux/sched/latency_tolerance.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_SCHED_LATENCY_TOLERANCE_H
+#define _LINUX_SCHED_LATENCY_TOLERANCE_H
+
+#define MAX_LATENCY_TOLERANCE 19
+#define MIN_LATENCY_TOLERANCE -20
+
+#define LATENCY_TOLERANCE_WIDTH \
+ (MAX_LATENCY_TOLERANCE - MIN_LATENCY_TOLERANCE + 1)
+
+#define DEFAULT_LATENCY_TOLERANCE 0
+
+#endif /* _LINUX_SCHED_LATENCY_TOLERANCE_H */
--
2.17.2
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