Commit-ID: e5137b50a0640009fd63a3e65c14bc6e1be8796a
Gitweb: http://git.kernel.org/tip/e5137b50a0640009fd63a3e65c14bc6e1be8796a
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Fri, 4 Oct 2013 17:28:26 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 11 Nov 2013 12:43:39 +0100
ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED
Since the introduction of PREEMPT_NEED_RESCHED in:
f27dde8deef3 ("sched: Add NEED_RESCHED to the preempt_count")
we need to be able to look at both TIF_NEED_RESCHED and
PREEMPT_NEED_RESCHED to understand the full preemption behaviour.
Add it to the trace output.
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Yuanhan Liu <yuanhan.liu@xxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20131004152826.GP3081@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
Documentation/trace/ftrace.txt | 6 +++++-
kernel/trace/trace.c | 3 ++-
kernel/trace/trace.h | 1 +
kernel/trace/trace_output.c | 19 +++++++++++++++++--
4 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index ea2d35d..bd36598 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -655,7 +655,11 @@ explains which is which.
read the irq flags variable, an 'X' will always
be printed here.
- need-resched: 'N' task need_resched is set, '.' otherwise.
+ need-resched:
+ 'N' both TIF_NEED_RESCHED and PREEMPT_NEED_RESCHED is set,
+ 'n' only TIF_NEED_RESCHED is set,
+ 'p' only PREEMPT_NEED_RESCHED is set,
+ '.' otherwise.
hardirq/softirq:
'H' - hard irq occurred inside a softirq.
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7974ba2..d9fea7d 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1509,7 +1509,8 @@ tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
#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);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 10c86fb..73d08aa 100644
--- 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
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index 34e7cba..ed32284 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -618,8 +618,23 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
(entry->flags & TRACE_FLAG_IRQS_OFF) ? 'd' :
(entry->flags & TRACE_FLAG_IRQS_NOSUPPORT) ? 'X' :
'.';
- need_resched =
- (entry->flags & TRACE_FLAG_NEED_RESCHED) ? 'N' : '.';
+
+ switch (entry->flags & (TRACE_FLAG_NEED_RESCHED |
+ TRACE_FLAG_PREEMPT_RESCHED)) {
+ case TRACE_FLAG_NEED_RESCHED | TRACE_FLAG_PREEMPT_RESCHED:
+ need_resched = 'N';
+ break;
+ case TRACE_FLAG_NEED_RESCHED:
+ need_resched = 'n';
+ break;
+ case TRACE_FLAG_PREEMPT_RESCHED:
+ need_resched = 'p';
+ break;
+ default:
+ need_resched = '.';
+ break;
+ }
+
hardsoft_irq =
(hardirq && softirq) ? 'H' :
hardirq ? 'h' :
--
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