Re: [PATCH v3 09/14] sched/core: uclamp: propagate parent clamps
From: Pavan Kondeti <hidden>
Date: 2018-08-16 09:09:20
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On Mon, Aug 06, 2018 at 05:39:41PM +0100, Patrick Bellasi wrote:
In order to properly support hierarchical resources control, the cgroup
delegation model requires that attribute writes from a child group never
fail but still are (potentially) constrained based on parent's assigned
resources. This requires to properly propagate and aggregate parent
attributes down to its descendants.
Let's implement this mechanism by adding a new "effective" clamp value
for each task group. The effective clamp value is defined as the smaller
value between the clamp value of a group and the effective clamp value
of its parent. This represent also the clamp value which is actually
used to clamp tasks in each task group.
Since it can be interesting for tasks in a cgroup to know exactly what
is the currently propagated/enforced configuration, the effective clamp
values are exposed to user-space by means of a new pair of read-only
attributes: cpu.util.{min,max}.effective.
Signed-off-by: Patrick Bellasi <redacted>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Rafael J. Wysocki <redacted>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Todd Kjos <redacted>
Cc: Joel Fernandes <redacted>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-pm@vger.kernel.org
<snip>
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diff --git a/include/linux/sched.h b/include/linux/sched.h index 8f48e64fb8a6..3fac2d098084 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h@@ -589,6 +589,11 @@ struct uclamp_se { unsigned int value; /* Utilization clamp group for this constraint */ unsigned int group_id; + /* Effective clamp for tasks in this group */ + struct { + unsigned int value; + unsigned int group_id; + } effective; };
Are these needed when CONFIG_UCLAMP_TASK_GROUP is disabled?
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union rcu_special {diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2ba55a4afffb..f692df3787bd 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c@@ -1237,6 +1237,8 @@ static inline void init_uclamp_sched_group(void) uc_se = &root_task_group.uclamp[clamp_id]; uc_se->value = uclamp_none(clamp_id); uc_se->group_id = group_id; + uc_se->effective.value = uclamp_none(clamp_id); + uc_se->effective.group_id = group_id; /* Attach root TG's clamp group */ uc_map[group_id].se_count = 1;
<snip>
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@@ -7622,11 +7687,19 @@ static struct cftype cpu_legacy_files[] = { .read_u64 = cpu_util_min_read_u64, .write_u64 = cpu_util_min_write_u64, }, + { + .name = "util.min.effective", + .read_u64 = cpu_util_min_effective_read_u64, + }, { .name = "util.max", .read_u64 = cpu_util_max_read_u64, .write_u64 = cpu_util_max_write_u64, }, + { + .name = "util.max.effective", + .read_u64 = cpu_util_max_effective_read_u64, + }, #endif { } /* Terminate */ };
Is there any reason why these are not added for the default hierarchy? Thanks, Pavan -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.