From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH 19/21] tracing: Account for preempt off in preempt_schedule()
Date: Thu, 22 Sep 2011 18:09:54 -0400 [thread overview]
Message-ID: <20110922221029.678324653@goodmis.org> (raw)
In-Reply-To: 20110922220935.537134016@goodmis.org
[-- Attachment #1: 0019-tracing-Account-for-preempt-off-in-preempt_schedule.patch --]
[-- Type: text/plain, Size: 1637 bytes --]
From: Steven Rostedt <srostedt@redhat.com>
The preempt_schedule() uses the preempt_disable_notrace() version
because it can cause infinite recursion by the function tracer as
the function tracer uses preempt_enable_notrace() which may call
back into the preempt_schedule() code as the NEED_RESCHED is still
set and the PREEMPT_ACTIVE has not been set yet.
See commit: d1f74e20b5b064a130cd0743a256c2d3cfe84010 that made this
change.
The preemptoff and preemptirqsoff latency tracers require the first
and last preempt count modifiers to enable tracing. But this skips
the checks. Since we can not convert them back to the non notrace
version, we can use the idle() hooks for the latency tracers here.
That is, the start/stop_critical_timings() works well to manually
start and stop the latency tracer for preempt off timings.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/sched.c | 9 +++++++++
1 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index ccacdbd..4b096cc 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4435,7 +4435,16 @@ asmlinkage void __sched notrace preempt_schedule(void)
do {
add_preempt_count_notrace(PREEMPT_ACTIVE);
+ /*
+ * The add/subtract must not be traced by the function
+ * tracer. But we still want to account for the
+ * preempt off latency tracer. Since the _notrace versions
+ * of add/subtract skip the accounting for latency tracer
+ * we must force it manually.
+ */
+ start_critical_timings();
schedule();
+ stop_critical_timings();
sub_preempt_count_notrace(PREEMPT_ACTIVE);
/*
--
1.7.5.4
next prev parent reply other threads:[~2011-09-22 22:10 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-22 22:09 [PATCH 00/21] [GIT PULL][v3.2] tracing: queued up stuff waiting for k.org to come back on line Steven Rostedt
2011-09-22 22:09 ` [PATCH 01/21] tracing: Clean up tb_fmt to not give faulty compile warning Steven Rostedt
2011-09-22 22:09 ` [PATCH 02/21] Tracepoint: Dissociate from module mutex Steven Rostedt
2011-09-22 22:09 ` [PATCH 03/21] x86: jump_label: arch_jump_label_text_poke_early: add missing __init Steven Rostedt
2011-09-22 22:09 ` [PATCH 04/21] tracing/filter: Use static allocation for filter predicates Steven Rostedt
2011-09-22 22:09 ` [PATCH 05/21] tracing/filter: Separate predicate init and filter addition Steven Rostedt
2011-09-22 22:09 ` [PATCH 06/21] tracing/filter: Remove field_name from filter_pred struct Steven Rostedt
2011-09-22 22:09 ` [PATCH 07/21] tracing/filter: Simplify tracepoint event lookup Steven Rostedt
2011-09-22 22:09 ` [PATCH 08/21] tracing/filter: Unify predicate tree walking, change check_pred_tree Steven Rostedt
2011-09-22 22:09 ` [PATCH 09/21] tracing/filter: Change count_leafs function to use walk_pred_tree Steven Rostedt
2011-09-22 22:09 ` [PATCH 10/21] tracing/filter: Change fold_pred_tree " Steven Rostedt
2011-09-22 22:09 ` [PATCH 11/21] tracing/filter: Change fold_pred " Steven Rostedt
2011-09-22 22:09 ` [PATCH 12/21] tracing/filter: Change filter_match_preds function to use Steven Rostedt
2011-09-22 22:09 ` [PATCH 13/21] tracing/filter: Add startup tests for events filter Steven Rostedt
2011-09-22 22:09 ` [PATCH 14/21] tracing: Add preempt disable for filter self test Steven Rostedt
2011-09-22 22:09 ` [PATCH 15/21] trace: Add a new readonly entry to report total buffer size Steven Rostedt
2011-09-22 22:09 ` [PATCH 16/21] trace: Add ring buffer stats to measure rate of events Steven Rostedt
2011-09-22 22:09 ` [PATCH 17/21] tracing: Add a counter clock for those that do not trust clocks Steven Rostedt
2011-09-22 22:09 ` [PATCH 18/21] tracing: Fix preemptirqsoff tracer to not stop at preempt off Steven Rostedt
2011-09-22 22:09 ` Steven Rostedt [this message]
2011-09-23 11:00 ` [PATCH 19/21] tracing: Account for preempt off in preempt_schedule() Peter Zijlstra
2011-09-23 11:19 ` Steven Rostedt
2011-09-23 11:22 ` Peter Zijlstra
2011-09-23 12:24 ` Steven Rostedt
2011-09-23 14:00 ` Peter Zijlstra
2011-09-23 14:07 ` Peter Zijlstra
2011-09-23 13:24 ` Peter Zijlstra
2011-09-22 22:09 ` [PATCH 20/21] tracing: Do not allocate buffer for trace_marker Steven Rostedt
2011-09-22 22:09 ` [PATCH 21/21] tracing: Add optional percpu buffers for trace_printk() Steven Rostedt
2011-09-23 11:02 ` Peter Zijlstra
2011-09-23 11:07 ` Peter Zijlstra
2011-09-23 11:16 ` Steven Rostedt
2011-09-23 11:28 ` Peter Zijlstra
2011-09-23 11:39 ` Steven Rostedt
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