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| author | Olof Johansson <olof@lixom.net> | 2013-07-12 19:59:39 +0200 |
|---|---|---|
| committer | Olof Johansson <olof@lixom.net> | 2013-07-12 19:59:39 +0200 |
| commit | f4b96f5e4ff8d86699c851c10245e102809b0331 (patch) | |
| tree | f766102263bed71738431cabb4d4f6f086005cd8 /Documentation/trace/events-nmi.txt | |
| parent | ARM: omap2: add select of TI_PRIV_EDMA (diff) | |
| parent | ARM: OMAP2+: omap2plus_defconfig: Enable appended DTB support (diff) | |
| download | linux-f4b96f5e4ff8d86699c851c10245e102809b0331.tar.xz linux-f4b96f5e4ff8d86699c851c10245e102809b0331.zip | |
Merge tag 'omap-for-v3.11/fixes-for-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into fixes
Omap fixes and minor defconfig updates that would be good to
get in before -rc1.
* tag 'omap-for-v3.11/fixes-for-merge-window' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
ARM: OMAP2+: omap2plus_defconfig: Enable appended DTB support
ARM: OMAP2+: Enable TI_EDMA in omap2plus_defconfig
ARM: OMAP2+: omap2plus_defconfig: enable DRA752 thermal support by default
ARM: OMAP2+: omap2plus_defconfig: enable TI bandgap driver
ARM: OMAP2+: devices: remove duplicated include from devices.c
ARM: OMAP3: igep0020: Set DSS pins in correct mux mode.
ARM: OMAP2+: N900: enable N900-specific drivers even if device tree is enabled
ARM: OMAP2+: Cocci spatch "ptr_ret.spatch"
ARM: OMAP2+: Remove obsolete Makefile line
ARM: OMAP5: Enable Cortex A15 errata 798181
ARM: scu: provide inline dummy functions when SCU is not present
ARM: OMAP4: sleep: build OMAP4 specific functions only for OMAP4
ARM: OMAP2+: timer: initialize before using oh_name
Signed-off-by: Olof Johansson <olof@lixom.net>
Add/move/change conflicts in arch/arm/mach-omap2/Kconfig resolved.
Diffstat (limited to 'Documentation/trace/events-nmi.txt')
| -rw-r--r-- | Documentation/trace/events-nmi.txt | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/Documentation/trace/events-nmi.txt b/Documentation/trace/events-nmi.txt new file mode 100644 index 000000000000..c03c8c89f08d --- /dev/null +++ b/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 + |