Messages in this thread Patch in this message |  | | Date | Wed, 12 Oct 2022 20:37:36 +0530 | Subject | Re: [PATCH v5 3/7] sched: Allow sched_{get,set}attr to change latency_nice of the task | From | K Prateek Nayak <> |
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Hello Vincent,
On 9/25/2022 8:09 PM, Vincent Guittot wrote: > From: Parth Shah <parth@linux.ibm.com> > > 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> > [rebase and add a dedicated __setscheduler_latency ] > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > --- > include/uapi/linux/sched.h | 4 +++- > include/uapi/linux/sched/types.h | 19 +++++++++++++++++++ > kernel/sched/core.c | 24 ++++++++++++++++++++++++ > tools/include/uapi/linux/sched.h | 4 +++- > 4 files changed, 49 insertions(+), 2 deletions(-) > > diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h > index 3bac0a8ceab2..b2e932c25be6 100644 > --- a/include/uapi/linux/sched.h > +++ b/include/uapi/linux/sched.h > @@ -132,6 +132,7 @@ 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
[1]
> > #define SCHED_FLAG_KEEP_ALL (SCHED_FLAG_KEEP_POLICY | \ > SCHED_FLAG_KEEP_PARAMS) > @@ -143,6 +144,7 @@ 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 f2c4589d4dbf..db1e8199e8c8 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. > @@ -98,6 +99,22 @@ struct sched_param { > * scheduled on a CPU with no more capacity than the specified value. > * > * A task utilization boundary can be reset by setting the attribute to -1. > + * > + * 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 > + * [MIN_LATENCY_NICE..MAX_LATENCY_NICE]. > + * > + * A task with latency_nice with the value of LATENCY_NICE_MIN can be > + * taken for a task requiring a lower latency as opposed to the task with > + * higher latency_nice. > */ > struct sched_attr { > __u32 size; > @@ -120,6 +137,8 @@ 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 ada2d05bd894..6a6116ea4c2c 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -7318,6 +7318,14 @@ 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); > + > +} > + > +static void __setscheduler_latency(struct task_struct *p, > + const struct sched_attr *attr) > +{ > + if (attr->sched_flags & SCHED_FLAG_LATENCY_NICE) > + p->latency_nice = attr->sched_latency_nice; > } > > /* > @@ -7460,6 +7468,13 @@ 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(); > > @@ -7494,6 +7509,9 @@ 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; > @@ -7582,6 +7600,7 @@ static int __sched_setscheduler(struct task_struct *p, > __setscheduler_params(p, attr); > __setscheduler_prio(p, newprio); > } > + __setscheduler_latency(p, attr); > __setscheduler_uclamp(p, attr); > > if (queued) { > @@ -7792,6 +7811,9 @@ 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? > @@ -8029,6 +8051,8 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, > get_params(p, &kattr); > kattr.sched_flags &= SCHED_FLAG_ALL; > > + kattr.sched_latency_nice = p->latency_nice; > + > #ifdef CONFIG_UCLAMP_TASK > /* > * This could race with another potential updater, but this is fine > diff --git a/tools/include/uapi/linux/sched.h b/tools/include/uapi/linux/sched.h > index 3bac0a8ceab2..ecc4884bfe4b 100644 > --- a/tools/include/uapi/linux/sched.h > +++ b/tools/include/uapi/linux/sched.h > @@ -132,6 +132,7 @@ 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
Small nit. Can you change the "x" in "0X80" to lower case here to make it consistent with [1] and other #define in the same file. When building tools like perf, I see the following warning:
Warning: Kernel ABI header at 'tools/include/uapi/linux/sched.h' differs from latest version at 'include/uapi/linux/sched.h' diff -u tools/include/uapi/linux/sched.h include/uapi/linux/sched.h
Following is the output of diff -u tools/include/uapi/linux/sched.h include/uapi/linux/sched.h
--- tools/include/uapi/linux/sched.h 2022-10-12 14:56:00.925360275 +0000 +++ include/uapi/linux/sched.h 2022-10-12 14:56:00.917360219 +0000 @@ -132,7 +132,7 @@ #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_LATENCY_NICE 0x80
#define SCHED_FLAG_KEEP_ALL (SCHED_FLAG_KEEP_POLICY | \ SCHED_FLAG_KEEP_PARAMS) -- > > #define SCHED_FLAG_KEEP_ALL (SCHED_FLAG_KEEP_POLICY | \ > SCHED_FLAG_KEEP_PARAMS) > @@ -143,6 +144,7 @@ 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 */
-- Thanks and Regards, Prateek
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