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[1.171.249.170]) by smtp.gmail.com with ESMTPSA id v196sm3276765pfc.34.2020.11.01.01.45.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 01 Nov 2020 01:45:08 -0700 (PDT) From: Yun Hsiang To: dietmar.eggemann@arm.com, peterz@infradead.org Cc: linux-kernel@vger.kernel.org, qais.yousef@arm.com, patrick.bellasi@matbug.net, Yun Hsiang Subject: [PATCH v4 1/1] sched/uclamp: add SCHED_FLAG_UTIL_CLAMP_RESET flag to reset uclamp Date: Sun, 1 Nov 2020 16:44:50 +0800 Message-Id: <20201101084450.985937-1-hsiang023167@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the user wants to stop controlling uclamp and let the task inherit the value from the group, we need a method to reset. Add SCHED_FLAG_UTIL_CLAMP_RESET flag to allow the user to reset uclamp via sched_setattr syscall. The policy is _CLAMP_RESET => reset both min and max _CLAMP_RESET | _CLAMP_MIN => reset min value _CLAMP_RESET | _CLAMP_MAX => reset max value _CLAMP_RESET | _CLAMP_MIN | _CLAMP_MAX => reset both min and max Signed-off-by: Yun Hsiang --- include/uapi/linux/sched.h | 7 +++-- kernel/sched/core.c | 59 ++++++++++++++++++++++++++++---------- 2 files changed, 49 insertions(+), 17 deletions(-) diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h index 3bac0a8ceab2..6c823ddb1a1e 100644 --- a/include/uapi/linux/sched.h +++ b/include/uapi/linux/sched.h @@ -132,17 +132,20 @@ struct clone_args { #define SCHED_FLAG_KEEP_PARAMS 0x10 #define SCHED_FLAG_UTIL_CLAMP_MIN 0x20 #define SCHED_FLAG_UTIL_CLAMP_MAX 0x40 +#define SCHED_FLAG_UTIL_CLAMP_RESET 0x80 #define SCHED_FLAG_KEEP_ALL (SCHED_FLAG_KEEP_POLICY | \ SCHED_FLAG_KEEP_PARAMS) #define SCHED_FLAG_UTIL_CLAMP (SCHED_FLAG_UTIL_CLAMP_MIN | \ - SCHED_FLAG_UTIL_CLAMP_MAX) + SCHED_FLAG_UTIL_CLAMP_MAX | \ + SCHED_FLAG_UTIL_CLAMP_RESET) #define SCHED_FLAG_ALL (SCHED_FLAG_RESET_ON_FORK | \ SCHED_FLAG_RECLAIM | \ SCHED_FLAG_DL_OVERRUN | \ SCHED_FLAG_KEEP_ALL | \ - SCHED_FLAG_UTIL_CLAMP) + SCHED_FLAG_UTIL_CLAMP | \ + SCHED_FLAG_UTIL_CLAMP_RESET) #endif /* _UAPI_LINUX_SCHED_H */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 8160ab5263f8..2b644f4bf2eb 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1004,7 +1004,7 @@ unsigned int uclamp_rq_max_value(struct rq *rq, enum uclamp_id clamp_id, return uclamp_idle_value(rq, clamp_id, clamp_value); } -static void __uclamp_update_util_min_rt_default(struct task_struct *p) +static inline void __uclamp_update_util_min_rt_default(struct task_struct *p) { unsigned int default_util_min; struct uclamp_se *uc_se; @@ -1413,8 +1413,14 @@ int sysctl_sched_uclamp_handler(struct ctl_table *table, int write, static int uclamp_validate(struct task_struct *p, const struct sched_attr *attr) { - unsigned int lower_bound = p->uclamp_req[UCLAMP_MIN].value; - unsigned int upper_bound = p->uclamp_req[UCLAMP_MAX].value; + unsigned int lower_bound, upper_bound; + + /* Do not check uclamp attributes values in reset case. */ + if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_RESET) + return 0; + + lower_bound = p->uclamp_req[UCLAMP_MIN].value; + upper_bound = p->uclamp_req[UCLAMP_MAX].value; if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) lower_bound = attr->sched_util_min; @@ -1438,20 +1444,43 @@ static int uclamp_validate(struct task_struct *p, return 0; } +static int uclamp_reset(enum uclamp_id clamp_id, unsigned long flags) +{ + /* No _UCLAMP_RESET flag set: do not reset */ + if (!(flags & SCHED_FLAG_UTIL_CLAMP_RESET)) + return false; + + /* Only _UCLAMP_RESET flag set: reset both clamps */ + if (!(flags & (SCHED_FLAG_UTIL_CLAMP_MIN | SCHED_FLAG_UTIL_CLAMP_MAX))) + return true; + + /* Both _UCLAMP_RESET and _UCLAMP_MIN flags are set: reset only min */ + if ((flags & SCHED_FLAG_UTIL_CLAMP_MIN) && clamp_id == UCLAMP_MIN) + return true; + + /* Both _UCLAMP_RESET and _UCLAMP_MAX flags are set: reset only max */ + if ((flags & SCHED_FLAG_UTIL_CLAMP_MAX) && clamp_id == UCLAMP_MAX) + return true; + + return false; +} + static void __setscheduler_uclamp(struct task_struct *p, const struct sched_attr *attr) { + unsigned int clamp_value; enum uclamp_id clamp_id; /* - * On scheduling class change, reset to default clamps for tasks - * without a task-specific value. + * Reset to default clamps on forced _UCLAMP_RESET (always) and + * for tasks without a task-specific value (on scheduling class change). */ for_each_clamp_id(clamp_id) { struct uclamp_se *uc_se = &p->uclamp_req[clamp_id]; /* Keep using defined clamps across class changes */ - if (uc_se->user_defined) + if (!uclamp_reset(clamp_id, attr->sched_flags) && + uc_se->user_defined) continue; /* @@ -1459,24 +1488,24 @@ static void __setscheduler_uclamp(struct task_struct *p, * at runtime. */ if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN)) - __uclamp_update_util_min_rt_default(p); + clamp_value = sysctl_sched_uclamp_util_min_rt_default; else - uclamp_se_set(uc_se, uclamp_none(clamp_id), false); + clamp_value = uclamp_none(clamp_id); + uclamp_se_set(uc_se, uclamp_none(clamp_id), false); } - if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP))) + if (likely(!(attr->sched_flags && SCHED_FLAG_UTIL_CLAMP)) || + attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_RESET) return; - if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) { + if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) uclamp_se_set(&p->uclamp_req[UCLAMP_MIN], - attr->sched_util_min, true); - } + attr->sched_util_min, true); - if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) { + if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) uclamp_se_set(&p->uclamp_req[UCLAMP_MAX], - attr->sched_util_max, true); - } + attr->sched_util_max, true); } static void uclamp_fork(struct task_struct *p) -- 2.25.1