Messages in this thread |  | | Date | Tue, 3 Dec 2019 08:39:16 +0000 | From | Qais Yousef <> | Subject | Re: [RFC 3/3] Allow sched_{get,set}attr to change latency_tolerance of the task |
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On 11/25/19 15:16, Parth Shah wrote: > Introduce the latency_tolerance 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_TOLERANCE" to hint the change in > latency_tolerance of the task on every sched_setattr syscall. > > Signed-off-by: Parth Shah <parth@linux.ibm.com> > --- > include/uapi/linux/sched.h | 4 +++- > include/uapi/linux/sched/types.h | 2 ++ > kernel/sched/core.c | 15 +++++++++++++++ > kernel/sched/sched.h | 1 + > 4 files changed, 21 insertions(+), 1 deletion(-) > > diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h > index b3105ac1381a..73db430d11b6 100644 > --- a/include/uapi/linux/sched.h > +++ b/include/uapi/linux/sched.h > @@ -71,6 +71,7 @@ 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_TOLERANCE 0x80 > > #define SCHED_FLAG_KEEP_ALL (SCHED_FLAG_KEEP_POLICY | \ > SCHED_FLAG_KEEP_PARAMS) > @@ -82,6 +83,7 @@ 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_TOLERANCE) > > #endif /* _UAPI_LINUX_SCHED_H */ > diff --git a/include/uapi/linux/sched/types.h b/include/uapi/linux/sched/types.h > index c852153ddb0d..960774ac0c70 100644 > --- a/include/uapi/linux/sched/types.h > +++ b/include/uapi/linux/sched/types.h > @@ -118,6 +118,8 @@ struct sched_attr { > __u32 sched_util_min; > __u32 sched_util_max; > > + /* latency requirement hints */ > + __s32 sched_latency_tolerance; > }; > > #endif /* _UAPI_LINUX_SCHED_TYPES_H */ > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index ea7abbf5c1bb..dfd36ec14404 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -4695,6 +4695,9 @@ 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); > + > + /* Change latency tolerance of the task if !SCHED_FLAG_KEEP_PARAMS */ > + p->latency_tolerance = attr->sched_latency_tolerance; > } > > /* Actually do priority change: must hold pi & rq lock. */ > @@ -4852,6 +4855,13 @@ static int __sched_setscheduler(struct task_struct *p, > return retval; > } > > + if (attr->sched_flags & SCHED_FLAG_LATENCY_TOLERANCE) { > + if (attr->sched_latency_tolerance > MAX_LATENCY_TOLERANCE) > + return -EINVAL; > + if (attr->sched_latency_tolerance < MIN_LATENCY_TOLERANCE) > + return -EINVAL; > + } > + > if (pi) > cpuset_read_lock(); > > @@ -4886,6 +4896,9 @@ 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_TOLERANCE && > + attr->sched_latency_tolerance != p->latency_tolerance) > + goto change; > > p->sched_reset_on_fork = reset_on_fork; > retval = 0; > @@ -5392,6 +5405,8 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, > else > kattr.sched_nice = task_nice(p); > > + kattr.sched_latency_tolerance = p->latency_tolerance; > + > #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/kernel/sched/sched.h b/kernel/sched/sched.h > index 0db2c1b3361e..bb181175954b 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -21,6 +21,7 @@ > #include <linux/sched/nohz.h> > #include <linux/sched/numa_balancing.h> > #include <linux/sched/prio.h> > +#include <linux/sched/latency_tolerance.h>
nit: keep in alphabatical order.
The series looks good to me except for the 2 minor nits. Thanks for taking care of this!
Reviewed-by: Qais Yousef <qais.yousef@arm.com>
Cheers
-- Qais Yousef
> #include <linux/sched/rt.h> > #include <linux/sched/signal.h> > #include <linux/sched/smt.h> > -- > 2.17.2 >
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