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tracing: Record and show NMI state

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The latency tracer format has a nice column to indicate IRQ state, but
this is not able to tell us about NMI state.

When tracing perf interrupt handlers (which often run in NMI context)
it is very useful to see how the events nest.

Link: http://lkml.kernel.org/r/20160318153022.105068893@infradead.org

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Peter Zijlstra 2016-03-18 16:28:04 +01:00 committed by Steven Rostedt
parent 3debb0a9dd
commit 7e6867bf83
3 changed files with 9 additions and 3 deletions
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1
kernel/trace/trace.c
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@ -1664,6 +1664,7 @@ tracing_generic_entry_update(struct trace_entry *entry, unsigned long flags,
#else
TRACE_FLAG_IRQS_NOSUPPORT |
#endif
((pc & NMI_MASK ) ? TRACE_FLAG_NMI : 0) |
((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
(tif_need_resched() ? TRACE_FLAG_NEED_RESCHED : 0) |

1
kernel/trace/trace.h
View File

@ -125,6 +125,7 @@ enum trace_flag_type {
TRACE_FLAG_HARDIRQ = 0x08,
TRACE_FLAG_SOFTIRQ = 0x10,
TRACE_FLAG_PREEMPT_RESCHED = 0x20,
TRACE_FLAG_NMI = 0x40,
};
#define TRACE_BUF_SIZE 1024

10
kernel/trace/trace_output.c
View File

@ -389,7 +389,9 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
char irqs_off;
int hardirq;
int softirq;
int nmi;
nmi = entry->flags & TRACE_FLAG_NMI;
hardirq = entry->flags & TRACE_FLAG_HARDIRQ;
softirq = entry->flags & TRACE_FLAG_SOFTIRQ;
@ -415,10 +417,12 @@ int trace_print_lat_fmt(struct trace_seq *s, struct trace_entry *entry)
}
hardsoft_irq =
(nmi && hardirq) ? 'Z' :
nmi ? 'z' :
(hardirq && softirq) ? 'H' :
hardirq ? 'h' :
softirq ? 's' :
'.';
hardirq ? 'h' :
softirq ? 's' :
'.' ;
trace_seq_printf(s, "%c%c%c",
irqs_off, need_resched, hardsoft_irq);