![Josh Poimboeuf](/assets/img/avatar_default.png)
Commit:cb2517653f
("sched/debug: Make schedstats a runtime tunable that is disabled by default") ... introduced a bug when CONFIG_SCHEDSTATS is enabled and the runtime tunable is disabled (which is the default). The wait-time, sum-exec, and sum-sleep fields are missing from the /proc/sched_debug file in the runnable_tasks section. Fix it with a new schedstat_val() macro which returns the field value when schedstats is enabled and zero otherwise. The macro works with both SCHEDSTATS and !SCHEDSTATS. I put the macro in stats.h since it might end up being useful in other places. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes:cb2517653f
("sched/debug: Make schedstats a runtime tunable that is disabled by default") Link: http://lkml.kernel.org/r/bcda7c2790cf2ccbe586a28c02dd7b6fe7749a2b.1464994423.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
268 lines
8 KiB
C
268 lines
8 KiB
C
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#ifdef CONFIG_SCHEDSTATS
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/*
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* Expects runqueue lock to be held for atomicity of update
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*/
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static inline void
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rq_sched_info_arrive(struct rq *rq, unsigned long long delta)
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{
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if (rq) {
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rq->rq_sched_info.run_delay += delta;
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rq->rq_sched_info.pcount++;
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}
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}
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/*
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* Expects runqueue lock to be held for atomicity of update
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*/
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static inline void
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rq_sched_info_depart(struct rq *rq, unsigned long long delta)
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{
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if (rq)
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rq->rq_cpu_time += delta;
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}
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static inline void
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rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
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{
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if (rq)
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rq->rq_sched_info.run_delay += delta;
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}
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# define schedstat_enabled() static_branch_unlikely(&sched_schedstats)
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# define schedstat_inc(rq, field) do { if (schedstat_enabled()) { (rq)->field++; } } while (0)
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# define schedstat_add(rq, field, amt) do { if (schedstat_enabled()) { (rq)->field += (amt); } } while (0)
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# define schedstat_set(var, val) do { if (schedstat_enabled()) { var = (val); } } while (0)
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# define schedstat_val(rq, field) ((schedstat_enabled()) ? (rq)->field : 0)
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#else /* !CONFIG_SCHEDSTATS */
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static inline void
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rq_sched_info_arrive(struct rq *rq, unsigned long long delta)
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{}
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static inline void
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rq_sched_info_dequeued(struct rq *rq, unsigned long long delta)
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{}
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static inline void
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rq_sched_info_depart(struct rq *rq, unsigned long long delta)
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{}
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# define schedstat_enabled() 0
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# define schedstat_inc(rq, field) do { } while (0)
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# define schedstat_add(rq, field, amt) do { } while (0)
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# define schedstat_set(var, val) do { } while (0)
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# define schedstat_val(rq, field) 0
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#endif
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#ifdef CONFIG_SCHED_INFO
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static inline void sched_info_reset_dequeued(struct task_struct *t)
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{
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t->sched_info.last_queued = 0;
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}
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/*
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* We are interested in knowing how long it was from the *first* time a
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* task was queued to the time that it finally hit a cpu, we call this routine
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* from dequeue_task() to account for possible rq->clock skew across cpus. The
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* delta taken on each cpu would annul the skew.
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*/
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static inline void sched_info_dequeued(struct rq *rq, struct task_struct *t)
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{
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unsigned long long now = rq_clock(rq), delta = 0;
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if (unlikely(sched_info_on()))
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if (t->sched_info.last_queued)
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delta = now - t->sched_info.last_queued;
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sched_info_reset_dequeued(t);
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t->sched_info.run_delay += delta;
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rq_sched_info_dequeued(rq, delta);
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}
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/*
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* Called when a task finally hits the cpu. We can now calculate how
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* long it was waiting to run. We also note when it began so that we
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* can keep stats on how long its timeslice is.
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*/
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static void sched_info_arrive(struct rq *rq, struct task_struct *t)
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{
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unsigned long long now = rq_clock(rq), delta = 0;
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if (t->sched_info.last_queued)
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delta = now - t->sched_info.last_queued;
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sched_info_reset_dequeued(t);
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t->sched_info.run_delay += delta;
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t->sched_info.last_arrival = now;
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t->sched_info.pcount++;
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rq_sched_info_arrive(rq, delta);
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}
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/*
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* This function is only called from enqueue_task(), but also only updates
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* the timestamp if it is already not set. It's assumed that
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* sched_info_dequeued() will clear that stamp when appropriate.
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*/
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static inline void sched_info_queued(struct rq *rq, struct task_struct *t)
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{
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if (unlikely(sched_info_on()))
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if (!t->sched_info.last_queued)
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t->sched_info.last_queued = rq_clock(rq);
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}
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/*
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* Called when a process ceases being the active-running process involuntarily
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* due, typically, to expiring its time slice (this may also be called when
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* switching to the idle task). Now we can calculate how long we ran.
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* Also, if the process is still in the TASK_RUNNING state, call
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* sched_info_queued() to mark that it has now again started waiting on
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* the runqueue.
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*/
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static inline void sched_info_depart(struct rq *rq, struct task_struct *t)
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{
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unsigned long long delta = rq_clock(rq) -
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t->sched_info.last_arrival;
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rq_sched_info_depart(rq, delta);
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if (t->state == TASK_RUNNING)
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sched_info_queued(rq, t);
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}
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/*
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* Called when tasks are switched involuntarily due, typically, to expiring
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* their time slice. (This may also be called when switching to or from
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* the idle task.) We are only called when prev != next.
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*/
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static inline void
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__sched_info_switch(struct rq *rq,
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struct task_struct *prev, struct task_struct *next)
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{
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/*
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* prev now departs the cpu. It's not interesting to record
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* stats about how efficient we were at scheduling the idle
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* process, however.
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*/
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if (prev != rq->idle)
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sched_info_depart(rq, prev);
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if (next != rq->idle)
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sched_info_arrive(rq, next);
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}
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static inline void
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sched_info_switch(struct rq *rq,
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struct task_struct *prev, struct task_struct *next)
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{
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if (unlikely(sched_info_on()))
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__sched_info_switch(rq, prev, next);
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}
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#else
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#define sched_info_queued(rq, t) do { } while (0)
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#define sched_info_reset_dequeued(t) do { } while (0)
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#define sched_info_dequeued(rq, t) do { } while (0)
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#define sched_info_depart(rq, t) do { } while (0)
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#define sched_info_arrive(rq, next) do { } while (0)
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#define sched_info_switch(rq, t, next) do { } while (0)
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#endif /* CONFIG_SCHED_INFO */
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/*
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* The following are functions that support scheduler-internal time accounting.
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* These functions are generally called at the timer tick. None of this depends
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* on CONFIG_SCHEDSTATS.
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*/
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/**
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* cputimer_running - return true if cputimer is running
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*
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* @tsk: Pointer to target task.
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*/
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static inline bool cputimer_running(struct task_struct *tsk)
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{
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struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
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/* Check if cputimer isn't running. This is accessed without locking. */
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if (!READ_ONCE(cputimer->running))
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return false;
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/*
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* After we flush the task's sum_exec_runtime to sig->sum_sched_runtime
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* in __exit_signal(), we won't account to the signal struct further
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* cputime consumed by that task, even though the task can still be
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* ticking after __exit_signal().
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*
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* In order to keep a consistent behaviour between thread group cputime
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* and thread group cputimer accounting, lets also ignore the cputime
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* elapsing after __exit_signal() in any thread group timer running.
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*
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* This makes sure that POSIX CPU clocks and timers are synchronized, so
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* that a POSIX CPU timer won't expire while the corresponding POSIX CPU
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* clock delta is behind the expiring timer value.
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*/
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if (unlikely(!tsk->sighand))
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return false;
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return true;
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}
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/**
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* account_group_user_time - Maintain utime for a thread group.
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*
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* @tsk: Pointer to task structure.
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* @cputime: Time value by which to increment the utime field of the
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* thread_group_cputime structure.
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*
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* If thread group time is being maintained, get the structure for the
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* running CPU and update the utime field there.
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*/
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static inline void account_group_user_time(struct task_struct *tsk,
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cputime_t cputime)
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{
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struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
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if (!cputimer_running(tsk))
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return;
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atomic64_add(cputime, &cputimer->cputime_atomic.utime);
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}
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/**
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* account_group_system_time - Maintain stime for a thread group.
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*
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* @tsk: Pointer to task structure.
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* @cputime: Time value by which to increment the stime field of the
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* thread_group_cputime structure.
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*
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* If thread group time is being maintained, get the structure for the
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* running CPU and update the stime field there.
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*/
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static inline void account_group_system_time(struct task_struct *tsk,
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cputime_t cputime)
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{
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struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
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if (!cputimer_running(tsk))
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return;
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atomic64_add(cputime, &cputimer->cputime_atomic.stime);
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}
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/**
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* account_group_exec_runtime - Maintain exec runtime for a thread group.
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*
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* @tsk: Pointer to task structure.
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* @ns: Time value by which to increment the sum_exec_runtime field
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* of the thread_group_cputime structure.
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*
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* If thread group time is being maintained, get the structure for the
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* running CPU and update the sum_exec_runtime field there.
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*/
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static inline void account_group_exec_runtime(struct task_struct *tsk,
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unsigned long long ns)
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{
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struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
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if (!cputimer_running(tsk))
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return;
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atomic64_add(ns, &cputimer->cputime_atomic.sum_exec_runtime);
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}
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