diff options
| author | Arnd Bergmann <arnd@arndb.de> | 2013-04-09 15:50:59 +0200 |
|---|---|---|
| committer | Arnd Bergmann <arnd@arndb.de> | 2013-04-09 16:01:23 +0200 |
| commit | 835f9c38bbb4498c3d43b7466964bdadbb1fd244 (patch) | |
| tree | ade5aec66bc7ddb97048c4f141932de0f93369b9 /kernel/trace/Kconfig | |
| parent | f5f29151588744ea2e283971cb0ad403ee04e3e2 (diff) | |
| parent | a937536b868b8369b98967929045f1df54234323 (diff) | |
Merge tag 'v3.9-rc3' into next/multiplatform
Linux 3.9-rc3
Conflicts:
arch/arm/Kconfig
arch/arm/mach-spear/spear3xx.c
arch/arm/plat-spear/Kconfig
This is a dependency for ux500/multiplatform
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'kernel/trace/Kconfig')
| -rw-r--r-- | kernel/trace/Kconfig | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 192473b22799..fc382d6e2765 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -414,24 +414,28 @@ config PROBE_EVENTS def_bool n config DYNAMIC_FTRACE - bool "enable/disable ftrace tracepoints dynamically" + bool "enable/disable function tracing dynamically" depends on FUNCTION_TRACER depends on HAVE_DYNAMIC_FTRACE default y help - This option will modify all the calls to ftrace dynamically - (will patch them out of the binary image and replace them - with a No-Op instruction) as they are called. A table is - created to dynamically enable them again. + This option will modify all the calls to function tracing + dynamically (will patch them out of the binary image and + replace them with a No-Op instruction) on boot up. During + compile time, a table is made of all the locations that ftrace + can function trace, and this table is linked into the kernel + image. When this is enabled, functions can be individually + enabled, and the functions not enabled will not affect + performance of the system. + + See the files in /sys/kernel/debug/tracing: + available_filter_functions + set_ftrace_filter + set_ftrace_notrace This way a CONFIG_FUNCTION_TRACER kernel is slightly larger, but otherwise has native performance as long as no tracing is active. - The changes to the code are done by a kernel thread that - wakes up once a second and checks to see if any ftrace calls - were made. If so, it runs stop_machine (stops all CPUS) - and modifies the code to jump over the call to ftrace. - config DYNAMIC_FTRACE_WITH_REGS def_bool y depends on DYNAMIC_FTRACE |