diff options
| author | Parth Shah <parth@linux.ibm.com> | 2020-02-28 14:37:52 +0530 |
|---|---|---|
| committer | Vincent Guittot <vincent.guittot@linaro.org> | 2022-01-20 14:36:24 +0100 |
| commit | 98b1a527ea0b5d8d09d8bebbcbc908066f875aaa (patch) | |
| tree | 1d6cbde02011c2bb313d11482e4dec04b340c0fb | |
| parent | 0e3872499de1a1230cef5221607d71aa09264bd5 (diff) | |
sched: Introduce latency-nice as a per-task attribute
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>
Reviewed-by: Qais Yousef <qais.yousef@arm.com>
| -rw-r--r-- | include/linux/sched.h | 1 | ||||
| -rw-r--r-- | kernel/sched/debug.c | 1 | ||||
| -rw-r--r-- | kernel/sched/sched.h | 18 |
3 files changed, 20 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 7f8b4495e243..a881eb2dda38 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -770,6 +770,7 @@ 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 aa29211de1bf..52997a4b550d 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -1053,6 +1053,7 @@ 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 de53be905739..fa299862c319 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -106,6 +106,24 @@ 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 * low-weight task groups (eg. nice +19 on an autogroup), deeper taskgroup |