From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754713AbbGFTP7 (ORCPT ); Mon, 6 Jul 2015 15:15:59 -0400 Received: from mail-pa0-f54.google.com ([209.85.220.54]:36657 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752023AbbGFTP4 (ORCPT ); Mon, 6 Jul 2015 15:15:56 -0400 From: Cong Wang To: linux-kernel@vger.kernel.org Cc: Cong Wang , Steven Rostedt , Ingo Molnar , Peter Zijlstra , Cong Wang Subject: [PATCH v2] sched: introduce sched_switch_post trace event Date: Mon, 6 Jul 2015 12:15:45 -0700 Message-Id: <1436210145-5520-1-git-send-email-xiyou.wangcong@gmail.com> X-Mailer: git-send-email 1.8.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently we only have one sched_switch trace event for task switching, which is generated very early during task switch. When we try to monitor per-container perf events, this is not what we expect. For example, we have a process A which is in the cgroup we monitor, and process B which isn't, when kernel switches from B to A, the sched_switch event is not recorded for this cgroup since it belongs to B (current process is still B util we finish the switch), but we require this event to signal that process A in this cgroup gets scheduled. This is crucial for calculating schedule latency (like `perf sched`). Ideally, we need to split the sched_switch event into two: sched_in event before we perform the switch, and sched_out event after we perform the switch. However, for compatibility, we can not change the sched_switch event. So before we have trace event alias, we can just reuse sched_switch and introduce sched_switch_post event instead. Suggested-by: Steven Rostedt Cc: Steven Rostedt Cc: Ingo Molnar Cc: Peter Zijlstra Signed-off-by: Cong Wang Signed-off-by: Cong Wang --- include/trace/events/sched.h | 43 ++++++++++++++++++++++++++++++++++++++++++- kernel/sched/core.c | 1 + 2 files changed, 43 insertions(+), 1 deletion(-) diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h index d57a575..4bc7db5 100644 --- a/include/trace/events/sched.h +++ b/include/trace/events/sched.h @@ -112,7 +112,9 @@ static inline long __trace_sched_switch_state(struct task_struct *p) #endif /* CREATE_TRACE_POINTS */ /* - * Tracepoint for task switches, performed by the scheduler: + * Tracepoints for task switches, performed by the scheduler: + * sched_switch is performed before task switch, + * sched_switch_post is performed after task switch. */ TRACE_EVENT(sched_switch, @@ -153,6 +155,45 @@ TRACE_EVENT(sched_switch, __entry->next_comm, __entry->next_pid, __entry->next_prio) ); +TRACE_EVENT(sched_switch_post, + + TP_PROTO(struct task_struct *prev, + struct task_struct *curr), + + TP_ARGS(prev, curr), + + TP_STRUCT__entry( + __array( char, prev_comm, TASK_COMM_LEN ) + __field( pid_t, prev_pid ) + __field( int, prev_prio ) + __field( long, prev_state ) + __array( char, curr_comm, TASK_COMM_LEN ) + __field( pid_t, curr_pid ) + __field( int, curr_prio ) + ), + + TP_fast_assign( + memcpy(__entry->curr_comm, curr->comm, TASK_COMM_LEN); + __entry->prev_pid = prev->pid; + __entry->prev_prio = prev->prio; + __entry->prev_state = __trace_sched_switch_state(prev); + memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN); + __entry->curr_pid = curr->pid; + __entry->curr_prio = curr->prio; + ), + + TP_printk("prev_comm=%s prev_pid=%d prev_prio=%d prev_state=%s%s ==> curr_comm=%s curr_pid=%d curr_prio=%d", + __entry->prev_comm, __entry->prev_pid, __entry->prev_prio, + __entry->prev_state & (TASK_STATE_MAX-1) ? + __print_flags(__entry->prev_state & (TASK_STATE_MAX-1), "|", + { 1, "S"} , { 2, "D" }, { 4, "T" }, { 8, "t" }, + { 16, "Z" }, { 32, "X" }, { 64, "x" }, + { 128, "K" }, { 256, "W" }, { 512, "P" }, + { 1024, "N" }) : "R", + __entry->prev_state & TASK_STATE_MAX ? "+" : "", + __entry->curr_comm, __entry->curr_pid, __entry->curr_prio) +); + /* * Tracepoint for a task being migrated: */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 78b4bad10..3c74cf4 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2490,6 +2490,7 @@ static struct rq *finish_task_switch(struct task_struct *prev) } tick_nohz_task_switch(current); + trace_sched_switch_post(prev, current); return rq; } -- 1.8.3.1