From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vincent Guittot Subject: [PATCH v12 2/8] sched: Introduce latency-nice as a per-task attribute Date: Fri, 24 Feb 2023 10:34:48 +0100 Message-ID: <20230224093454.956298-3-vincent.guittot@linaro.org> References: <20230224093454.956298-1-vincent.guittot@linaro.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=kiVS63wbAWm+QNHUVgj2Zht/JYfZt2Iaghb+UJPmGJA=; b=QrTYP59UXLyEyZXXYAeeXw2AFfFauFp/C2n/IOyN3xqbAk8jjk7e20YwjW4/43PsBi 4QPrI/QTUmePR3SOLNczxnpoBs5aDDxAEopDH+YvwI2cwTf4AF65FfzRnZObTfbN+Hec WFZO5EQCCOfR7bZFaP2tJLma9p8iRxA7DlUro5Z4PqHmwHBB+u2FhNfrug7WVn7wubU3 GzPZ6F/YVjhhCLmMkMui/c6pr2O5+yI85Yufy2TgrbyHe/rdl02i5nnCM0km4exhBi3P cJhw7ozhoXe+F0JqtenV03G1YlpZGakYFvT8fC0bLeE7ExceapOsAmy4aB88jY7A/oFs 835g== In-Reply-To: <20230224093454.956298-1-vincent.guittot@linaro.org> List-ID: Content-Type: text/plain; charset="us-ascii" To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, linux-kernel@vger.kernel.org, parth@linux.ibm.com, tj@kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org, cgroups@vger.kernel.org, corbet@lwn.net, linux-doc@vger.kernel.org Cc: qyousef@layalina.io, chris.hyser@oracle.com, patrick.bellasi@matbug.net, David.Laight@aculab.com, pjt@google.com, pavel@ucw.cz, qperret@google.com, tim.c.chen@linux.intel.com, joshdon@google.com, timj@gnu.org, kprateek.nayak@amd.com, yu.c.chen@intel.com, youssefesmat@chromium.org, joel@joelfernandes.org, Vincent Guittot From: Parth Shah 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 [rebase, move defines in sched/prio.h] Signed-off-by: Vincent Guittot Tested-by: K Prateek Nayak --- include/linux/sched.h | 1 + include/linux/sched/prio.h | 18 ++++++++++++++++++ kernel/sched/debug.c | 1 + 3 files changed, 20 insertions(+) diff --git a/include/linux/sched.h b/include/linux/sched.h index 4df2b3e76b30..6c61bde49152 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -784,6 +784,7 @@ 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/include/linux/sched/prio.h b/include/linux/sched/prio.h index ab83d85e1183..bfcd7f1d1e11 100644 --- a/include/linux/sched/prio.h +++ b/include/linux/sched/prio.h @@ -42,4 +42,22 @@ static inline long rlimit_to_nice(long prio) return (MAX_NICE - prio + 1); } +/* + * 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 + #endif /* _LINUX_SCHED_PRIO_H */ diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 1637b65ba07a..68be7a3e42a3 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); -- 2.34.1