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charset="utf-8" Trace thread's preemption getting delayed. Which can occur if the running thread requested extra time on cpu. Also, indicate the NEED_RESCHED flag, that is set on the thread, getting cleared. Suggested-by: Sebastian Andrzej Siewior Signed-off-by: Prakash Sangappa --- v5 -> v6 - Changed tracepoint to tracepoint condition. --- include/trace/events/sched.h | 31 +++++++++++++++++++++++++++++++ kernel/entry/common.c | 10 ++++++++-- 2 files changed, 39 insertions(+), 2 deletions(-) diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h index 4e6b2910cec3..a4846579f377 100644 --- a/include/trace/events/sched.h +++ b/include/trace/events/sched.h @@ -296,6 +296,37 @@ TRACE_EVENT(sched_migrate_task, __entry->orig_cpu, __entry->dest_cpu) ); =20 +/* + * Tracepoint for delayed resched requested by task: + */ +TRACE_EVENT_CONDITION(sched_delay_resched, + + TP_PROTO(struct task_struct *p, unsigned int ti_work_cleared), + + TP_ARGS(p, ti_work_cleared), + + TP_CONDITION(ti_work_cleared), + + TP_STRUCT__entry( + __array( char, comm, TASK_COMM_LEN ) + __field( pid_t, pid ) + __field( int, cpu ) + __field( int, flg ) + ), + + TP_fast_assign( + memcpy(__entry->comm, p->comm, TASK_COMM_LEN); + __entry->pid =3D p->pid; + __entry->cpu =3D task_cpu(p); + __entry->flg =3D ti_work_cleared & (_TIF_NEED_RESCHED | + _TIF_NEED_RESCHED_LAZY); + ), + + TP_printk("comm=3D%s pid=3D%d cpu=3D%d resched_flg_cleared=3D0x%x", + __entry->comm, __entry->pid, __entry->cpu, __entry->flg) + +); + DECLARE_EVENT_CLASS(sched_process_template, =20 TP_PROTO(struct task_struct *p), diff --git a/kernel/entry/common.c b/kernel/entry/common.c index 8769c3592e26..ca3c91f0ea99 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -12,6 +12,7 @@ =20 #include "common.h" =20 +#include #define CREATE_TRACE_POINTS #include =20 @@ -91,6 +92,7 @@ __always_inline unsigned long exit_to_user_mode_loop(stru= ct pt_regs *regs, unsigned long ti_work, bool irq) { + unsigned long ti_work_cleared =3D 0; /* * Before returning to user space ensure that all pending work * items have been completed. @@ -100,10 +102,12 @@ __always_inline unsigned long exit_to_user_mode_loop(= struct pt_regs *regs, local_irq_enable_exit_to_user(ti_work); =20 if (ti_work & (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY)) { - if (irq && rseq_delay_resched()) + if (irq && rseq_delay_resched()) { clear_tsk_need_resched(current); - else + ti_work_cleared =3D ti_work; + } else { schedule(); + } } =20 if (ti_work & _TIF_UPROBE) @@ -134,6 +138,8 @@ __always_inline unsigned long exit_to_user_mode_loop(st= ruct pt_regs *regs, ti_work =3D read_thread_flags(); } =20 + trace_sched_delay_resched(current, ti_work_cleared); + /* Return the latest work state for arch_exit_to_user_mode() */ return ti_work; } --=20 2.43.5