From: Arjan van de Ven Date: Sat, 21 Aug 2010 20:07:26 +0000 (-0700) Subject: workqueue: Add basic tracepoints to track workqueue execution X-Git-Tag: Ubuntu-5.0.0-8.9~21775 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=e36c886a0f9d624377977fa6cae309cfd7f362fa;p=mirror_ubuntu-disco-kernel.git workqueue: Add basic tracepoints to track workqueue execution With the introduction of the new unified work queue thread pools, we lost one feature: It's no longer possible to know which worker is causing the CPU to wake out of idle. The result is that PowerTOP now reports a lot of "kworker/a:b" instead of more readable results. This patch adds a pair of tracepoints to the new workqueue code, similar in style to the timer/hrtimer tracepoints. With this pair of tracepoints, the next PowerTOP can correctly report which work item caused the wakeup (and how long it took): Interrupt (43) i915 time 3.51ms wakeups 141 Work ieee80211_iface_work time 0.81ms wakeups 29 Work do_dbs_timer time 0.55ms wakeups 24 Process Xorg time 21.36ms wakeups 4 Timer sched_rt_period_timer time 0.01ms wakeups 1 Signed-off-by: Arjan van de Ven Signed-off-by: Linus Torvalds --- diff --git a/include/trace/events/workqueue.h b/include/trace/events/workqueue.h new file mode 100644 index 000000000000..49682d7e9d60 --- /dev/null +++ b/include/trace/events/workqueue.h @@ -0,0 +1,62 @@ +#undef TRACE_SYSTEM +#define TRACE_SYSTEM workqueue + +#if !defined(_TRACE_WORKQUEUE_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_WORKQUEUE_H + +#include +#include + +/** + * workqueue_execute_start - called immediately before the workqueue callback + * @work: pointer to struct work_struct + * + * Allows to track workqueue execution. + */ +TRACE_EVENT(workqueue_execute_start, + + TP_PROTO(struct work_struct *work), + + TP_ARGS(work), + + TP_STRUCT__entry( + __field( void *, work ) + __field( void *, function) + ), + + TP_fast_assign( + __entry->work = work; + __entry->function = work->func; + ), + + TP_printk("work struct %p: function %pf", __entry->work, __entry->function) +); + +/** + * workqueue_execute_end - called immediately before the workqueue callback + * @work: pointer to struct work_struct + * + * Allows to track workqueue execution. + */ +TRACE_EVENT(workqueue_execute_end, + + TP_PROTO(struct work_struct *work), + + TP_ARGS(work), + + TP_STRUCT__entry( + __field( void *, work ) + ), + + TP_fast_assign( + __entry->work = work; + ), + + TP_printk("work struct %p", __entry->work) +); + + +#endif /* _TRACE_WORKQUEUE_H */ + +/* This part must be outside protection */ +#include diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 2994a0e3a61c..8bd600c020e5 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -35,6 +35,9 @@ #include #include +#define CREATE_TRACE_POINTS +#include + #include "workqueue_sched.h" enum { @@ -1790,7 +1793,13 @@ static void process_one_work(struct worker *worker, struct work_struct *work) work_clear_pending(work); lock_map_acquire(&cwq->wq->lockdep_map); lock_map_acquire(&lockdep_map); + trace_workqueue_execute_start(work); f(work); + /* + * While we must be careful to not use "work" after this, the trace + * point will only record its address. + */ + trace_workqueue_execute_end(work); lock_map_release(&lockdep_map); lock_map_release(&cwq->wq->lockdep_map);