From 8e52fd71e693619f7a58de2692e59f0c826e9988 Mon Sep 17 00:00:00 2001 From: Michael Jeanson Date: Mon, 4 Apr 2022 13:52:57 -0400 Subject: [PATCH 03/10] fix: sched/tracing: Don't re-read p->state when emitting sched_switch event (v5.18) See upstream commit : commit fa2c3254d7cfff5f7a916ab928a562d1165f17bb Author: Valentin Schneider Date: Thu Jan 20 16:25:19 2022 +0000 sched/tracing: Don't re-read p->state when emitting sched_switch event As of commit c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu") the following sequence becomes possible: p->__state = TASK_INTERRUPTIBLE; __schedule() deactivate_task(p); ttwu() READ !p->on_rq p->__state=TASK_WAKING trace_sched_switch() __trace_sched_switch_state() task_state_index() return 0; TASK_WAKING isn't in TASK_REPORT, so the task appears as TASK_RUNNING in the trace event. Prevent this by pushing the value read from __schedule() down the trace event. Upstream-Status: Backport Change-Id: I46743cd006be4b4d573cae2d77df7d6d16744d04 Signed-off-by: Michael Jeanson Signed-off-by: Mathieu Desnoyers --- include/instrumentation/events/sched.h | 88 +++++++++++++++++++++++--- 1 file changed, 78 insertions(+), 10 deletions(-) diff --git a/include/instrumentation/events/sched.h b/include/instrumentation/events/sched.h index 91953a6f..339bec94 100644 --- a/include/instrumentation/events/sched.h +++ b/include/instrumentation/events/sched.h @@ -20,7 +20,37 @@ #ifndef _TRACE_SCHED_DEF_ #define _TRACE_SCHED_DEF_ -#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,15,0)) +#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,18,0)) + +static inline long __trace_sched_switch_state(bool preempt, + unsigned int prev_state, + struct task_struct *p) +{ + unsigned int state; + +#ifdef CONFIG_SCHED_DEBUG + BUG_ON(p != current); +#endif /* CONFIG_SCHED_DEBUG */ + + /* + * Preemption ignores task state, therefore preempted tasks are always + * RUNNING (we will not have dequeued if state != RUNNING). + */ + if (preempt) + return TASK_REPORT_MAX; + + /* + * task_state_index() uses fls() and returns a value from 0-8 range. + * Decrement it by 1 (except TASK_RUNNING state i.e 0) before using + * it for left shift operation to get the correct task->state + * mapping. + */ + state = __task_state_index(prev_state, p->exit_state); + + return state ? (1 << (state - 1)) : state; +} + +#elif (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,15,0)) static inline long __trace_sched_switch_state(bool preempt, struct task_struct *p) { @@ -321,43 +351,81 @@ LTTNG_TRACEPOINT_EVENT_INSTANCE(sched_wakeup_template, sched_wakeup_new, /* * Tracepoint for task switches, performed by the scheduler: */ + +#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(5,18,0)) LTTNG_TRACEPOINT_EVENT(sched_switch, -#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,4,0)) TP_PROTO(bool preempt, - struct task_struct *prev, - struct task_struct *next), + unsigned int prev_state, + struct task_struct *prev, + struct task_struct *next), - TP_ARGS(preempt, prev, next), + TP_ARGS(preempt, prev_state, prev, next), + + TP_FIELDS( + ctf_array_text(char, prev_comm, prev->comm, TASK_COMM_LEN) + ctf_integer(pid_t, prev_tid, prev->pid) + ctf_integer(int, prev_prio, prev->prio - MAX_RT_PRIO) +#ifdef CONFIG_LTTNG_EXPERIMENTAL_BITWISE_ENUM + ctf_enum(task_state, long, prev_state, __trace_sched_switch_state(preempt, prev_state, prev)) #else - TP_PROTO(struct task_struct *prev, + ctf_integer(long, prev_state, __trace_sched_switch_state(preempt, prev_state, prev)) +#endif + ctf_array_text(char, next_comm, next->comm, TASK_COMM_LEN) + ctf_integer(pid_t, next_tid, next->pid) + ctf_integer(int, next_prio, next->prio - MAX_RT_PRIO) + ) +) + +#elif (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,4,0)) + +LTTNG_TRACEPOINT_EVENT(sched_switch, + + TP_PROTO(bool preempt, + struct task_struct *prev, struct task_struct *next), - TP_ARGS(prev, next), -#endif /* #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,4,0)) */ + TP_ARGS(preempt, prev, next), TP_FIELDS( ctf_array_text(char, prev_comm, prev->comm, TASK_COMM_LEN) ctf_integer(pid_t, prev_tid, prev->pid) ctf_integer(int, prev_prio, prev->prio - MAX_RT_PRIO) -#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,4,0)) #ifdef CONFIG_LTTNG_EXPERIMENTAL_BITWISE_ENUM ctf_enum(task_state, long, prev_state, __trace_sched_switch_state(preempt, prev)) #else ctf_integer(long, prev_state, __trace_sched_switch_state(preempt, prev)) #endif + ctf_array_text(char, next_comm, next->comm, TASK_COMM_LEN) + ctf_integer(pid_t, next_tid, next->pid) + ctf_integer(int, next_prio, next->prio - MAX_RT_PRIO) + ) +) + #else + +LTTNG_TRACEPOINT_EVENT(sched_switch, + + TP_PROTO(struct task_struct *prev, + struct task_struct *next), + + TP_ARGS(prev, next), + + TP_FIELDS( + ctf_array_text(char, prev_comm, prev->comm, TASK_COMM_LEN) + ctf_integer(pid_t, prev_tid, prev->pid) + ctf_integer(int, prev_prio, prev->prio - MAX_RT_PRIO) #ifdef CONFIG_LTTNG_EXPERIMENTAL_BITWISE_ENUM ctf_enum(task_state, long, prev_state, __trace_sched_switch_state(prev)) #else ctf_integer(long, prev_state, __trace_sched_switch_state(prev)) -#endif #endif ctf_array_text(char, next_comm, next->comm, TASK_COMM_LEN) ctf_integer(pid_t, next_tid, next->pid) ctf_integer(int, next_prio, next->prio - MAX_RT_PRIO) ) ) +#endif /* * Tracepoint for a task being migrated: -- 2.19.1