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Subject[PATCH] ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED
Subject: ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED
From: Peter Zijlstra <peterz@infradead.org>
Date: Fri Sep 27 17:11:00 CEST 2013

Since we now have two need_resched states; trace the two so we can
observe discrepancies.

Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
---
kernel/trace/trace.c | 3 ++-
kernel/trace/trace.h | 1 +
kernel/trace/trace_output.c | 13 +++++++++++--
3 files changed, 14 insertions(+), 3 deletions(-)

--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1509,7 +1509,8 @@ tracing_generic_entry_update(struct trac
#endif
((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
- (need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
+ (tif_need_resched() ? TRACE_FLAG_NEED_RESCHED : 0) |
+ (test_preempt_need_resched() ? TRACE_FLAG_PREEMPT_RESCHED : 0);
}
EXPORT_SYMBOL_GPL(tracing_generic_entry_update);

--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -124,6 +124,7 @@ enum trace_flag_type {
TRACE_FLAG_NEED_RESCHED = 0x04,
TRACE_FLAG_HARDIRQ = 0x08,
TRACE_FLAG_SOFTIRQ = 0x10,
+ TRACE_FLAG_PREEMPT_RESCHED = 0x20,
};

#define TRACE_BUF_SIZE 1024
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -618,8 +618,17 @@ int trace_print_lat_fmt(struct trace_seq
(entry->flags & TRACE_FLAG_IRQS_OFF) ? 'd' :
(entry->flags & TRACE_FLAG_IRQS_NOSUPPORT) ? 'X' :
'.';
- need_resched =
- (entry->flags & TRACE_FLAG_NEED_RESCHED) ? 'N' : '.';
+
+ if ((entry->flags & TRACE_FLAG_NEED_RESCHED) &&
+ (entry->flags & TRACE_FLAG_PREEMPT_RESCHED))
+ need_resched = 'N';
+ else if (entry->flags & TRACE_FLAG_NEED_RESCHED)
+ need_resched = 'n';
+ else if (entry->flags & TRACE_FLAG_PREEMPT_RESCHED)
+ need_resched = 'p';
+ else
+ need_resched = '.';
+
hardsoft_irq =
(hardirq && softirq) ? 'H' :
hardirq ? 'h' :

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