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author | David S. Miller <davem@davemloft.net> | 2010-05-19 02:01:55 -0400 |
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committer | David S. Miller <davem@davemloft.net> | 2010-05-19 02:01:55 -0400 |
commit | 2ec8c6bb5d8f3a62a79f463525054bae1e3d4487 (patch) | |
tree | fa7f8400ac685fb52e96f64997c7c682fc2aa021 /Documentation/trace/ftrace.txt | |
parent | 7b39f90fabcf9e2af0cd79d0a60440d821e22b56 (diff) | |
parent | 537b60d17894b7c19a6060feae40299d7109d6e7 (diff) |
Merge branch 'master' of /home/davem/src/GIT/linux-2.6/
Conflicts:
include/linux/mod_devicetable.h
scripts/mod/file2alias.c
Diffstat (limited to 'Documentation/trace/ftrace.txt')
-rw-r--r-- | Documentation/trace/ftrace.txt | 50 |
1 files changed, 48 insertions, 2 deletions
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt index 03485bfbd797..557c1edeccaf 100644 --- a/Documentation/trace/ftrace.txt +++ b/Documentation/trace/ftrace.txt | |||
@@ -155,6 +155,9 @@ of ftrace. Here is a list of some of the key files: | |||
155 | to be traced. Echoing names of functions into this file | 155 | to be traced. Echoing names of functions into this file |
156 | will limit the trace to only those functions. | 156 | will limit the trace to only those functions. |
157 | 157 | ||
158 | This interface also allows for commands to be used. See the | ||
159 | "Filter commands" section for more details. | ||
160 | |||
158 | set_ftrace_notrace: | 161 | set_ftrace_notrace: |
159 | 162 | ||
160 | This has an effect opposite to that of | 163 | This has an effect opposite to that of |
@@ -1337,12 +1340,14 @@ ftrace_dump_on_oops must be set. To set ftrace_dump_on_oops, one | |||
1337 | can either use the sysctl function or set it via the proc system | 1340 | can either use the sysctl function or set it via the proc system |
1338 | interface. | 1341 | interface. |
1339 | 1342 | ||
1340 | sysctl kernel.ftrace_dump_on_oops=1 | 1343 | sysctl kernel.ftrace_dump_on_oops=n |
1341 | 1344 | ||
1342 | or | 1345 | or |
1343 | 1346 | ||
1344 | echo 1 > /proc/sys/kernel/ftrace_dump_on_oops | 1347 | echo n > /proc/sys/kernel/ftrace_dump_on_oops |
1345 | 1348 | ||
1349 | If n = 1, ftrace will dump buffers of all CPUs, if n = 2 ftrace will | ||
1350 | only dump the buffer of the CPU that triggered the oops. | ||
1346 | 1351 | ||
1347 | Here's an example of such a dump after a null pointer | 1352 | Here's an example of such a dump after a null pointer |
1348 | dereference in a kernel module: | 1353 | dereference in a kernel module: |
@@ -1822,6 +1827,47 @@ this special filter via: | |||
1822 | echo > set_graph_function | 1827 | echo > set_graph_function |
1823 | 1828 | ||
1824 | 1829 | ||
1830 | Filter commands | ||
1831 | --------------- | ||
1832 | |||
1833 | A few commands are supported by the set_ftrace_filter interface. | ||
1834 | Trace commands have the following format: | ||
1835 | |||
1836 | <function>:<command>:<parameter> | ||
1837 | |||
1838 | The following commands are supported: | ||
1839 | |||
1840 | - mod | ||
1841 | This command enables function filtering per module. The | ||
1842 | parameter defines the module. For example, if only the write* | ||
1843 | functions in the ext3 module are desired, run: | ||
1844 | |||
1845 | echo 'write*:mod:ext3' > set_ftrace_filter | ||
1846 | |||
1847 | This command interacts with the filter in the same way as | ||
1848 | filtering based on function names. Thus, adding more functions | ||
1849 | in a different module is accomplished by appending (>>) to the | ||
1850 | filter file. Remove specific module functions by prepending | ||
1851 | '!': | ||
1852 | |||
1853 | echo '!writeback*:mod:ext3' >> set_ftrace_filter | ||
1854 | |||
1855 | - traceon/traceoff | ||
1856 | These commands turn tracing on and off when the specified | ||
1857 | functions are hit. The parameter determines how many times the | ||
1858 | tracing system is turned on and off. If unspecified, there is | ||
1859 | no limit. For example, to disable tracing when a schedule bug | ||
1860 | is hit the first 5 times, run: | ||
1861 | |||
1862 | echo '__schedule_bug:traceoff:5' > set_ftrace_filter | ||
1863 | |||
1864 | These commands are cumulative whether or not they are appended | ||
1865 | to set_ftrace_filter. To remove a command, prepend it by '!' | ||
1866 | and drop the parameter: | ||
1867 | |||
1868 | echo '!__schedule_bug:traceoff' > set_ftrace_filter | ||
1869 | |||
1870 | |||
1825 | trace_pipe | 1871 | trace_pipe |
1826 | ---------- | 1872 | ---------- |
1827 | 1873 | ||