From: Vincent Guittot <vincent.guittot@linaro.org>
To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, mgorman@suse.de,
linux-kernel@vger.kernel.org, parth@linux.ibm.com
Cc: qais.yousef@arm.com, chris.hyser@oracle.com,
pkondeti@codeaurora.org, valentin.schneider@arm.com,
patrick.bellasi@matbug.net, David.Laight@aculab.com,
pjt@google.com, pavel@ucw.cz, tj@kernel.org,
dhaval.giani@oracle.com, qperret@google.com,
tim.c.chen@linux.intel.com,
Vincent Guittot <vincent.guittot@linaro.org>
Subject: [PATCH 1/6] sched: Introduce latency-nice as a per-task attribute
Date: Fri, 11 Mar 2022 17:14:01 +0100 [thread overview]
Message-ID: <20220311161406.23497-2-vincent.guittot@linaro.org> (raw)
In-Reply-To: <20220311161406.23497-1-vincent.guittot@linaro.org>
From: Parth Shah <parth@linux.ibm.com>
Latency-nice 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_nice = -20 indicates the task to have the least latency as
compared to the tasks having latency_nice = +19.
The latency_nice may affect only the CFS SCHED_CLASS by getting
latency requirements from the userspace.
Additionally, add debugging bits for newly added latency_nice attribute.
Signed-off-by: Parth Shah <parth@linux.ibm.com>
[rebase]
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---
include/linux/sched.h | 1 +
kernel/sched/debug.c | 1 +
kernel/sched/sched.h | 18 ++++++++++++++++++
3 files changed, 20 insertions(+)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 508b91d57470..2aa889a59054 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -779,6 +779,7 @@ struct task_struct {
int static_prio;
int normal_prio;
unsigned int rt_priority;
+ int latency_nice;
struct sched_entity se;
struct sched_rt_entity rt;
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 102d6f70e84d..5d76a8927888 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -1043,6 +1043,7 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
#endif
P(policy);
P(prio);
+ P(latency_nice);
if (task_has_dl_policy(p)) {
P(dl.runtime);
P(dl.deadline);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 9b33ba9c3c42..456ad2159eb1 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -105,6 +105,24 @@ extern void call_trace_sched_update_nr_running(struct rq *rq, int count);
*/
#define NS_TO_JIFFIES(TIME) ((unsigned long)(TIME) / (NSEC_PER_SEC / HZ))
+/*
+ * Latency nice is meant to provide scheduler hints about the relative
+ * latency requirements of a task with respect to other tasks.
+ * Thus a task with latency_nice == 19 can be hinted as the task with no
+ * latency requirements, in contrast to the task with latency_nice == -20
+ * which should be given priority in terms of lower latency.
+ */
+#define MAX_LATENCY_NICE 19
+#define MIN_LATENCY_NICE -20
+
+#define LATENCY_NICE_WIDTH \
+ (MAX_LATENCY_NICE - MIN_LATENCY_NICE + 1)
+
+/*
+ * Default tasks should be treated as a task with latency_nice = 0.
+ */
+#define DEFAULT_LATENCY_NICE 0
+
/*
* Increase resolution of nice-level calculations for 64-bit architectures.
* The extra resolution improves shares distribution and load balancing of
--
2.17.1
next prev parent reply other threads:[~2022-03-11 16:14 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-11 16:14 [PATCH 0/6] Add latency_nice priority Vincent Guittot
2022-03-11 16:14 ` Vincent Guittot [this message]
2022-03-11 16:14 ` [PATCH 2/6] sched/core: Propagate parent task's latency requirements to the child task Vincent Guittot
2022-03-22 0:22 ` Tim Chen
2022-03-22 14:57 ` Vincent Guittot
2022-03-11 16:14 ` [PATCH 3/6] sched: Allow sched_{get,set}attr to change latency_nice of the task Vincent Guittot
2022-03-22 0:22 ` Tim Chen
2022-03-22 14:55 ` Vincent Guittot
2022-03-28 9:23 ` Dietmar Eggemann
2022-03-28 12:41 ` Vincent Guittot
2022-03-11 16:14 ` [PATCH 4/6] sched/core: Add permission checks for setting the latency_nice value Vincent Guittot
2022-03-11 16:14 ` [RFC 5/6] sched/fair: Take into account latency nice at wakeup Vincent Guittot
2022-03-15 0:53 ` Josh Don
2022-03-15 13:54 ` Vincent Guittot
2022-03-28 9:24 ` Dietmar Eggemann
2022-03-28 12:51 ` Vincent Guittot
2022-05-01 15:58 ` Tao Zhou
2022-05-02 9:54 ` Vincent Guittot
2022-05-02 12:30 ` Vincent Guittot
2022-05-02 15:08 ` Tao Zhou
2022-05-02 15:26 ` Tao Zhou
2022-05-02 15:47 ` Tao Zhou
2022-05-02 16:21 ` Vincent Guittot
2022-05-02 23:09 ` Tao Zhou
2022-05-03 2:30 ` Tao Zhou
2022-05-03 12:40 ` Vincent Guittot
2022-05-04 11:14 ` Chen Yu
2022-05-04 12:39 ` Vincent Guittot
2022-03-11 16:14 ` [RFC 6/6] sched/fair: Add sched group latency support Vincent Guittot
2022-03-15 0:58 ` Josh Don
2022-03-15 17:07 ` Vincent Guittot
2022-03-21 17:24 ` Tejun Heo
2022-03-22 16:10 ` Vincent Guittot
2022-03-22 16:40 ` Tejun Heo
2022-03-23 15:04 ` Vincent Guittot
2022-03-23 18:20 ` Chris Hyser
2022-03-22 16:41 ` Tim Chen
2022-03-23 15:23 ` Vincent Guittot
2022-03-22 16:39 ` [PATCH 0/6] Add latency_nice priority Qais Yousef
2022-03-23 15:32 ` Vincent Guittot
2022-03-24 17:25 ` Qais Yousef
2022-03-25 13:27 ` Vincent Guittot
2022-03-28 16:27 ` Qais Yousef
2022-03-30 7:30 ` Vincent Guittot
2022-03-28 9:24 ` Dietmar Eggemann
2022-03-28 12:56 ` Vincent Guittot
2022-04-01 12:15 ` Qais Yousef
2022-04-02 8:46 ` Vincent Guittot
2022-04-09 17:08 ` Qais Yousef
2022-04-09 17:28 ` Steven Rostedt
2022-04-09 18:10 ` Qais Yousef
2022-04-11 7:26 ` Vincent Guittot
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