Messages in this thread |  | | From | Vincent Guittot <> | Date | Wed, 12 Oct 2022 17:44:38 +0200 | Subject | Re: [PATCH v5 3/7] sched: Allow sched_{get,set}attr to change latency_nice of the task |
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On Wed, 12 Oct 2022 at 17:07, K Prateek Nayak <kprateek.nayak@amd.com> wrote: > > 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:
Yes, that's a typo. It should be 0x80
> > 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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