From: Patrick Bellasi <patrick.bellasi@arm.com>
To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>, Tejun Heo <tj@kernel.org>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Paul Turner <pjt@google.com>,
Quentin Perret <quentin.perret@arm.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Juri Lelli <juri.lelli@redhat.com>, Todd Kjos <tkjos@google.com>,
Joel Fernandes <joelaf@google.com>,
Steve Muckle <smuckle@google.com>,
Suren Baghdasaryan <surenb@google.com>,
linux-api@vger.kernel.org
Subject: [PATCH v5 02/15] sched/core: make sched_setattr able to tune the current policy
Date: Mon, 29 Oct 2018 18:32:56 +0000 [thread overview]
Message-ID: <20181029183311.29175-3-patrick.bellasi@arm.com> (raw)
In-Reply-To: <20181029183311.29175-1-patrick.bellasi@arm.com>
Currently, sched_setattr mandates that a policy is always specified.
Since utilization clamp attributes could apply across different
scheduling policies (i.e. all but SCHED_DEADLINE), this requires also
to always know which policy a task has before changing its clamp values.
This is not just cumbersome but it's also racy, indeed we cannot be
sure that a task policy has been changed in between its policy read and
the actual clamp value change. Sometimes however, this could be the
actual use-case, we wanna change the clamps without affecting the
policy.
Let's fix this adding an additional attribute flag
(SCHED_FLAG_TUNE_POLICY) which, when specified, will ensure to always
force the usage of the current policy. This is done by re-using the
SETPARAM_POLICY thing we already have for the sched_setparam syscall,
thus extending its usage to the non-POSIX sched_setattr while not
exposing that internal concept to user-space.
Signed-off-by: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linux-api@vger.kernel.org
---
Changes in v5:
Message-ID: <20180905110108.GC20267@localhost.localdomain>
- allow to change clamp values without affecting current policy
---
include/uapi/linux/sched.h | 6 +++++-
kernel/sched/core.c | 11 ++++++++++-
2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h
index c27d6e81517b..62498d749bec 100644
--- a/include/uapi/linux/sched.h
+++ b/include/uapi/linux/sched.h
@@ -40,6 +40,8 @@
/* SCHED_ISO: reserved but not implemented yet */
#define SCHED_IDLE 5
#define SCHED_DEADLINE 6
+/* Must be the last entry: used check attr.policy values */
+#define SCHED_POLICY_MAX 7
/* Can be ORed in to make sure the process is reverted back to SCHED_NORMAL on fork */
#define SCHED_RESET_ON_FORK 0x40000000
@@ -50,11 +52,13 @@
#define SCHED_FLAG_RESET_ON_FORK 0x01
#define SCHED_FLAG_RECLAIM 0x02
#define SCHED_FLAG_DL_OVERRUN 0x04
-#define SCHED_FLAG_UTIL_CLAMP 0x08
+#define SCHED_FLAG_TUNE_POLICY 0x08
+#define SCHED_FLAG_UTIL_CLAMP 0x10
#define SCHED_FLAG_ALL (SCHED_FLAG_RESET_ON_FORK | \
SCHED_FLAG_RECLAIM | \
SCHED_FLAG_DL_OVERRUN | \
+ SCHED_FLAG_TUNE_POLICY | \
SCHED_FLAG_UTIL_CLAMP)
#endif /* _UAPI_LINUX_SCHED_H */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 3701bb1e6698..9a2e12eaa377 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4595,8 +4595,17 @@ SYSCALL_DEFINE3(sched_setattr, pid_t, pid, struct sched_attr __user *, uattr,
if (retval)
return retval;
- if ((int)attr.sched_policy < 0)
+ /*
+ * A valid policy has always to be required from userspace. Unless
+ * the SCHED_FLAG_TUNE_POLICY is set, in which case, the current
+ * policy will be enforced for this call.
+ */
+ if (attr.sched_policy >= SCHED_POLICY_MAX &&
+ !(attr.sched_flags & SCHED_FLAG_TUNE_POLICY)) {
return -EINVAL;
+ }
+ if (attr.sched_flags & SCHED_FLAG_TUNE_POLICY)
+ attr.sched_policy = SETPARAM_POLICY;
rcu_read_lock();
retval = -ESRCH;
--
2.18.0
next prev parent reply other threads:[~2018-10-29 18:33 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-29 18:32 [PATCH v5 00/15] Add utilization clamping support Patrick Bellasi
2018-10-29 18:32 ` [PATCH v5 01/15] sched/core: uclamp: extend sched_setattr to support utilization clamping Patrick Bellasi
2018-10-29 19:33 ` Randy Dunlap
2018-11-07 12:09 ` Peter Zijlstra
2018-10-29 18:32 ` Patrick Bellasi [this message]
2018-11-07 12:11 ` [PATCH v5 02/15] sched/core: make sched_setattr able to tune the current policy Peter Zijlstra
2018-11-07 13:50 ` Patrick Bellasi
2018-11-07 13:58 ` Peter Zijlstra
2018-10-29 18:32 ` [PATCH v5 03/15] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups Patrick Bellasi
2018-11-07 12:19 ` Peter Zijlstra
2018-11-07 14:19 ` Patrick Bellasi
2018-11-07 14:42 ` Peter Zijlstra
2018-11-07 14:56 ` Patrick Bellasi
2018-11-07 13:16 ` Peter Zijlstra
2018-11-07 13:57 ` Patrick Bellasi
2018-11-07 14:14 ` Peter Zijlstra
2018-11-07 13:35 ` Peter Zijlstra
2018-11-07 14:48 ` Patrick Bellasi
2018-11-07 14:55 ` Peter Zijlstra
2018-11-07 15:04 ` Patrick Bellasi
2018-11-07 13:44 ` Peter Zijlstra
2018-11-07 14:24 ` Patrick Bellasi
2018-11-07 14:44 ` Peter Zijlstra
2018-11-07 14:58 ` Patrick Bellasi
2018-11-07 14:37 ` Peter Zijlstra
2018-11-07 14:53 ` Patrick Bellasi
2018-10-29 18:32 ` [PATCH v5 04/15] sched/core: uclamp: add CPU's clamp groups accounting Patrick Bellasi
2018-10-29 18:42 ` Patrick Bellasi
2018-10-29 18:32 ` [PATCH v5 04/15] sched/core: uclamp: add CPU's clamp groups refcounting Patrick Bellasi
2018-11-11 16:47 ` Peter Zijlstra
2018-11-13 15:11 ` Patrick Bellasi
2018-11-22 14:20 ` Patrick Bellasi
2018-10-29 18:33 ` [PATCH v5 05/15] sched/core: uclamp: update CPU's refcount on clamp changes Patrick Bellasi
2018-10-29 18:33 ` [PATCH v5 06/15] sched/core: uclamp: enforce last task UCLAMP_MAX Patrick Bellasi
2018-11-11 17:08 ` Peter Zijlstra
2018-11-13 15:14 ` Patrick Bellasi
2018-10-29 18:33 ` [PATCH v5 07/15] sched/core: uclamp: add clamp group bucketing support Patrick Bellasi
2018-11-12 0:09 ` Peter Zijlstra
2018-11-13 15:29 ` Patrick Bellasi
2018-10-29 18:33 ` [PATCH v5 08/15] sched/core: uclamp: add system default clamps Patrick Bellasi
2018-10-29 18:33 ` [PATCH v5 09/15] sched/cpufreq: uclamp: add utilization clamping for FAIR tasks Patrick Bellasi
2018-11-07 11:38 ` Patrick Bellasi
2018-10-29 18:33 ` [PATCH v5 10/15] sched/cpufreq: uclamp: add utilization clamping for RT tasks Patrick Bellasi
2018-10-29 18:33 ` [PATCH v5 11/15] sched/core: uclamp: extend CPU's cgroup controller Patrick Bellasi
2018-10-29 18:33 ` [PATCH v5 12/15] sched/core: uclamp: propagate parent clamps Patrick Bellasi
2018-10-29 18:33 ` [PATCH v5 13/15] sched/core: uclamp: map TG's clamp values into CPU's clamp groups Patrick Bellasi
2018-10-29 18:33 ` [PATCH v5 14/15] sched/core: uclamp: use TG's clamps to restrict Task's clamps Patrick Bellasi
2018-10-29 18:47 ` Patrick Bellasi
2018-10-29 18:33 ` [PATCH v5 14/15] sched/core: uclamp: use TG's clamps to restrict TASK's clamps Patrick Bellasi
2018-10-29 18:33 ` [PATCH v5 15/15] sched/core: uclamp: update CPU's refcount on TG's clamp changes Patrick Bellasi
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