----- On Sep 23, 2016, at 12:49 PM, Julien Desfossez jdesfos...@efficios.com
wrote:
> This tracepoint allows to keep track of all explicit priority changes of
> a task. It outputs the scheduling policy, the nice value, the
> rt_priority and the deadline-related attributes (dl_runtime, dl_deadline
> and dl_period).
>
> It is emitted in the code path of the sched_setscheduler, sched_setattr,
> sched_setparam, and nice system calls.
>
> This allows the analysis of real-time scheduling delays based on the
> configured scheduling priorities and policies, which cannot be performed
> with the current instrumentation in sched_switch. Also, instead of
> exposing the internal kernel prio field, this tracepoint only outputs
> the user-visible priority attributes.
>
> The effective priority of running threads can also be temporarily
> changed in the PI code, but a dedicated tracepoint is already in place
> to cover this case.
>
> Here are a few output examples:
> After fork of a normal task:
> sched_update_prio: comm=bash pid=2104, policy=SCHED_NORMAL, nice=0,
> rt_priority=0, dl_runtime=0, dl_deadline=0, dl_period=0
>
> renice -n 10 of a normal task:
> sched_update_prio: comm=sleep pid=2130, policy=SCHED_NORMAL, nice=10,
> rt_priority=0, dl_runtime=0, dl_deadline=0, dl_period=0
>
> SCHED_FIFO 60:
> sched_update_prio: comm=chrt pid=2105, policy=SCHED_FIFO, nice=0,
> rt_priority=60, dl_runtime=0, dl_deadline=0, dl_period=0
>
> SCHED_RR 60:
> sched_update_prio: comm=chrt pid=2109, policy=SCHED_RR, nice=0,
> rt_priority=60, dl_runtime=0, dl_deadline=0, dl_period=0
>
> SCHED_DEADLINE:
> sched_update_prio: comm=b pid=2110, policy=SCHED_DEADLINE, nice=0,
> rt_priority=0, dl_runtime=10000000, dl_deadline=30000000,
> dl_period=30000000
>
> Cc: Peter Zijlstra <pet...@infradead.org>
> Cc: Steven Rostedt (Red Hat) <rost...@goodmis.org>
> Cc: Thomas Gleixner <t...@linutronix.de>
> Cc: Ingo Molnar <mi...@redhat.com>
> Reviewed-by: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
> Signed-off-by: Julien Desfossez <jdesfos...@efficios.com>
> ---
> include/trace/events/sched.h | 68 ++++++++++++++++++++++++++++++++++++++++++++
> kernel/sched/core.c | 3 ++
> 2 files changed, 71 insertions(+)
>
> diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
> index 582357d..8d3343b 100644
> --- a/include/trace/events/sched.h
> +++ b/include/trace/events/sched.h
> @@ -8,6 +8,34 @@
> #include <linux/tracepoint.h>
> #include <linux/binfmts.h>
>
> +#define SCHEDULING_POLICY \
> + EM( SCHED_NORMAL, "SCHED_NORMAL") \
> + EM( SCHED_FIFO, "SCHED_FIFO") \
> + EM( SCHED_RR, "SCHED_RR") \
> + EM( SCHED_BATCH, "SCHED_BATCH") \
> + EM( SCHED_IDLE, "SCHED_IDLE") \
> + EMe(SCHED_DEADLINE, "SCHED_DEADLINE")
> +
As spotted by the build bot, you should either move this
definition to patch 3/5 (which requires it), or reorder your
patchset to put this patch before the two that require it.
> +/*
> + * First define the enums in the above macros to be exported to userspace
> + * via TRACE_DEFINE_ENUM().
> + */
> +#undef EM
> +#undef EMe
> +#define EM(a, b) TRACE_DEFINE_ENUM(a);
> +#define EMe(a, b) TRACE_DEFINE_ENUM(a);
> +
> +SCHEDULING_POLICY
> +
> +/*
> + * Now redefine the EM() and EMe() macros to map the enums to the strings
> + * that will be printed in the output.
> + */
> +#undef EM
> +#undef EMe
> +#define EM(a, b) {a, b},
> +#define EMe(a, b) {a, b}
> +
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
