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    Subject[PATCH 2/2] tracing, sched: Add a new tracepoint for sleeptime
    Date
    If CONFIG_SCHEDSTATS is defined, the kernel maintains
    information about how long the task was sleeping or
    in the case of iowait, blocking in the kernel before
    getting woken up.

    Note: this information is only provided for sched_fair.
    Other scheduling classes may choose to provide this in
    the future.

    Note: the delay includes the time spent on the runqueue
    as well.

    Signed-off-by: Arun Sharma <asharma@fb.com>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
    Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
    Cc: Andrew Vagin <avagin@openvz.org>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: linux-kernel@vger.kernel.org
    ---
    include/trace/events/sched.h | 48 ++++++++++++++++++++++++++++++++++++++++++
    kernel/sched/core.c | 1 +
    2 files changed, 49 insertions(+), 0 deletions(-)

    diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
    index 959ff18..5189220 100644
    --- a/include/trace/events/sched.h
    +++ b/include/trace/events/sched.h
    @@ -363,6 +363,54 @@ TRACE_EVENT(sched_stat_runtime,
    (unsigned long long)__entry->vruntime)
    );

    +#ifdef CREATE_TRACE_POINTS
    +static inline u64 trace_get_sleeptime(struct task_struct *tsk)
    +{
    +#ifdef CONFIG_SCHEDSTATS
    + u64 block, sleep;
    +
    + block = tsk->se.statistics.block_start;
    + sleep = tsk->se.statistics.sleep_start;
    +
    + return block ? block : sleep ? sleep : 0;
    +#else
    + return 0;
    +#endif
    +}
    +#endif
    +
    +/*
    + * Tracepoint for accounting sleeptime (time the task is sleeping
    + * or waiting for I/O).
    + */
    +TRACE_EVENT(sched_stat_sleeptime,
    +
    + TP_PROTO(struct task_struct *tsk, u64 now),
    +
    + TP_ARGS(tsk, now),
    +
    + TP_STRUCT__entry(
    + __array( char, comm, TASK_COMM_LEN )
    + __field( pid_t, pid )
    + __field( u64, sleeptime )
    + ),
    +
    + TP_fast_assign(
    + memcpy(__entry->comm, tsk->comm, TASK_COMM_LEN);
    + __entry->pid = tsk->pid;
    + __entry->sleeptime = trace_get_sleeptime(tsk);
    + __entry->sleeptime = __entry->sleeptime ?
    + now - __entry->sleeptime : 0;
    + )
    + TP_perf_assign(
    + __perf_count(__entry->sleeptime);
    + ),
    +
    + TP_printk("comm=%s pid=%d sleeptime=%Lu [ns]",
    + __entry->comm, __entry->pid,
    + (unsigned long long)__entry->sleeptime)
    +);
    +
    /*
    * Tracepoint for showing priority inheritance modifying a tasks
    * priority.
    diff --git a/kernel/sched/core.c b/kernel/sched/core.c
    index ca8fd44..172e6ee 100644
    --- a/kernel/sched/core.c
    +++ b/kernel/sched/core.c
    @@ -1899,6 +1899,7 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev)
    local_irq_enable();
    #endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
    finish_lock_switch(rq, prev);
    + trace_sched_stat_sleeptime(current, rq->clock);

    fire_sched_in_preempt_notifiers(current);
    if (mm)
    --
    1.7.4


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