1 ================
2 NMI Trace Events
3 ================
4
5 These events normally show up here:
6
7 /sys/kernel/tracing/events/nmi
8
9
10 nmi_handler
11 -----------
12
13 You might want to use this tracepoint if you s
14 NMI handlers are hogging large amounts of CPU
15 will warn if it sees long-running handlers::
16
17 INFO: NMI handler took too long to run
18
19 and this tracepoint will allow you to drill do
20 more details.
21
22 Let's say you suspect that perf_event_nmi_hand
23 you some problems and you only want to trace t
24 specifically. You need to find its address::
25
26 $ grep perf_event_nmi_handler /proc/ka
27 ffffffff81625600 t perf_event_nmi_hand
28
29 Let's also say you are only interested in when
30 really hogging a lot of CPU time, like a milli
31 Note that the kernel's output is in millisecon
32 to the filter is in nanoseconds! You can filt
33
34 cd /sys/kernel/tracing/events/nmi/nmi_
35 echo 'handler==0xffffffff81625600 && d
36 echo 1 > enable
37
38 Your output would then look like::
39
40 $ cat /sys/kernel/tracing/trace_pipe
41 <idle>-0 [000] d.h3 505.397558:
42 <idle>-0 [000] d.h3 505.805893:
43 <idle>-0 [000] d.h3 506.158206:
44 <idle>-0 [000] d.h3 506.334346:
45
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