Messages in this thread Patch in this message | | | From | Parth Shah <> | Subject | [PATCH v5 3/4] sched: Allow sched_{get,set}attr to change latency_nice of the task | Date | Fri, 28 Feb 2020 14:37:54 +0530 |
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Introduce the latency_nice attribute to sched_attr and provide a mechanism to change the value with the use of sched_setattr/sched_getattr syscall.
Also add new flag "SCHED_FLAG_LATENCY_NICE" to hint the change in latency_nice of the task on every sched_setattr syscall.
Signed-off-by: Parth Shah <parth@linux.ibm.com> Reviewed-by: Qais Yousef <qais.yousef@arm.com> --- include/uapi/linux/sched.h | 4 +++- include/uapi/linux/sched/types.h | 19 +++++++++++++++++++ kernel/sched/core.c | 18 ++++++++++++++++++ tools/include/uapi/linux/sched.h | 4 +++- 4 files changed, 43 insertions(+), 2 deletions(-)
diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h index 2e3bc22c6f20..8778c51c7953 100644 --- a/include/uapi/linux/sched.h +++ b/include/uapi/linux/sched.h @@ -127,6 +127,7 @@ 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_LATENCY_NICE 0x80 #define SCHED_FLAG_KEEP_ALL (SCHED_FLAG_KEEP_POLICY | \ SCHED_FLAG_KEEP_PARAMS) @@ -138,6 +139,7 @@ struct clone_args { SCHED_FLAG_RECLAIM | \ SCHED_FLAG_DL_OVERRUN | \ SCHED_FLAG_KEEP_ALL | \ - SCHED_FLAG_UTIL_CLAMP) + SCHED_FLAG_UTIL_CLAMP | \ + SCHED_FLAG_LATENCY_NICE) #endif /* _UAPI_LINUX_SCHED_H */ diff --git a/include/uapi/linux/sched/types.h b/include/uapi/linux/sched/types.h index c852153ddb0d..626ab61c1145 100644 --- a/include/uapi/linux/sched/types.h +++ b/include/uapi/linux/sched/types.h @@ -10,6 +10,7 @@ struct sched_param { #define SCHED_ATTR_SIZE_VER0 48 /* sizeof first published struct */ #define SCHED_ATTR_SIZE_VER1 56 /* add: util_{min,max} */ +#define SCHED_ATTR_SIZE_VER2 60 /* add: latency_nice */ /* * Extended scheduling parameters data structure. @@ -96,6 +97,22 @@ struct sched_param { * on a CPU with a capacity big enough to fit the specified value. * A task with a max utilization value smaller than 1024 is more likely * scheduled on a CPU with no more capacity than the specified value. + * + * Latency Tolerance Attributes + * =========================== + * + * A subset of sched_attr attributes allows to specify the relative latency + * requirements of a task with respect to the other tasks running/queued in the + * system. + * + * @ sched_latency_nice task's latency_nice value + * + * The latency_nice of a task can have any value in a range of + * [LATENCY_NICE_MIN..LATENCY_NICE_MAX]. + * + * A task with latency_nice with the value of LATENCY_NICE_MIN can be + * taken for a task with lower latency requirements as opposed to the task with + * higher latency_nice. */ struct sched_attr { __u32 size; @@ -118,6 +135,8 @@ struct sched_attr { __u32 sched_util_min; __u32 sched_util_max; + /* latency requirement hints */ + __s32 sched_latency_nice; }; #endif /* _UAPI_LINUX_SCHED_TYPES_H */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 866ea3d2d284..cd1fb9c8be26 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4710,6 +4710,9 @@ static void __setscheduler_params(struct task_struct *p, p->rt_priority = attr->sched_priority; p->normal_prio = normal_prio(p); set_load_weight(p, true); + + if (attr->sched_flags & SCHED_FLAG_LATENCY_NICE) + p->latency_nice = attr->sched_latency_nice; } /* Actually do priority change: must hold pi & rq lock. */ @@ -4867,6 +4870,13 @@ static int __sched_setscheduler(struct task_struct *p, return retval; } + if (attr->sched_flags & SCHED_FLAG_LATENCY_NICE) { + if (attr->sched_latency_nice > MAX_LATENCY_NICE) + return -EINVAL; + if (attr->sched_latency_nice < MIN_LATENCY_NICE) + return -EINVAL; + } + if (pi) cpuset_read_lock(); @@ -4901,6 +4911,9 @@ static int __sched_setscheduler(struct task_struct *p, goto change; if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP) goto change; + if (attr->sched_flags & SCHED_FLAG_LATENCY_NICE && + attr->sched_latency_nice != p->latency_nice) + goto change; p->sched_reset_on_fork = reset_on_fork; retval = 0; @@ -5149,6 +5162,9 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a size < SCHED_ATTR_SIZE_VER1) return -EINVAL; + if ((attr->sched_flags & SCHED_FLAG_LATENCY_NICE) && + size < SCHED_ATTR_SIZE_VER2) + return -EINVAL; /* * XXX: Do we want to be lenient like existing syscalls; or do we want * to be strict and return an error on out-of-bounds values? @@ -5378,6 +5394,8 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, else kattr.sched_nice = task_nice(p); + kattr.sched_latency_nice = p->latency_nice; + #ifdef CONFIG_UCLAMP_TASK kattr.sched_util_min = p->uclamp_req[UCLAMP_MIN].value; kattr.sched_util_max = p->uclamp_req[UCLAMP_MAX].value; diff --git a/tools/include/uapi/linux/sched.h b/tools/include/uapi/linux/sched.h index 2e3bc22c6f20..94adc87df0e6 100644 --- a/tools/include/uapi/linux/sched.h +++ b/tools/include/uapi/linux/sched.h @@ -127,6 +127,7 @@ 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_LATENCY_NICE 0X80 #define SCHED_FLAG_KEEP_ALL (SCHED_FLAG_KEEP_POLICY | \ SCHED_FLAG_KEEP_PARAMS) @@ -138,6 +139,7 @@ struct clone_args { SCHED_FLAG_RECLAIM | \ SCHED_FLAG_DL_OVERRUN | \ SCHED_FLAG_KEEP_ALL | \ - SCHED_FLAG_UTIL_CLAMP) + SCHED_FLAG_UTIL_CLAMP | \ + SCHED_FLAG_LATENCY_NICE) #endif /* _UAPI_LINUX_SCHED_H */ -- 2.17.2
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