diff options
| author |   Yunhong Jiang <yunhong.jiang@intel.com> | 2015-08-04 12:17:53 -0700 |
|---|---|---|
| committer | Yunhong Jiang <yunhong.jiang@intel.com> | 2015-08-04 15:44:42 -0700 |
| commit | 9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch) | |
| tree | 1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/trace/events-nmi.txt | |
| parent | 98260f3884f4a202f9ca5eabed40b1354c489b29 (diff) | |
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base.
It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:
commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat Jul 25 12:13:34 2015 +0200
Prepare v4.1.3-rt3
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.
Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Diffstat (limited to 'kernel/Documentation/trace/events-nmi.txt')
| -rw-r--r-- | kernel/Documentation/trace/events-nmi.txt | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/kernel/Documentation/trace/events-nmi.txt b/kernel/Documentation/trace/events-nmi.txt new file mode 100644 index 000000000..c03c8c89f --- /dev/null +++ b/kernel/Documentation/trace/events-nmi.txt @@ -0,0 +1,43 @@ +NMI Trace Events + +These events normally show up here: + + /sys/kernel/debug/tracing/events/nmi + +-- + +nmi_handler: + +You might want to use this tracepoint if you suspect that your +NMI handlers are hogging large amounts of CPU time. The kernel +will warn if it sees long-running handlers: + + INFO: NMI handler took too long to run: 9.207 msecs + +and this tracepoint will allow you to drill down and get some +more details. + +Let's say you suspect that perf_event_nmi_handler() is causing +you some problems and you only want to trace that handler +specifically. You need to find its address: + + $ grep perf_event_nmi_handler /proc/kallsyms + ffffffff81625600 t perf_event_nmi_handler + +Let's also say you are only interested in when that function is +really hogging a lot of CPU time, like a millisecond at a time. +Note that the kernel's output is in milliseconds, but the input +to the filter is in nanoseconds! You can filter on 'delta_ns': + +cd /sys/kernel/debug/tracing/events/nmi/nmi_handler +echo 'handler==0xffffffff81625600 && delta_ns>1000000' > filter +echo 1 > enable + +Your output would then look like: + +$ cat /sys/kernel/debug/tracing/trace_pipe +<idle>-0 [000] d.h3 505.397558: nmi_handler: perf_event_nmi_handler() delta_ns: 3236765 handled: 1 +<idle>-0 [000] d.h3 505.805893: nmi_handler: perf_event_nmi_handler() delta_ns: 3174234 handled: 1 +<idle>-0 [000] d.h3 506.158206: nmi_handler: perf_event_nmi_handler() delta_ns: 3084642 handled: 1 +<idle>-0 [000] d.h3 506.334346: nmi_handler: perf_event_nmi_handler() delta_ns: 3080351 handled: 1 + |