Messages in this thread Patch in this message | | | Date | Fri, 28 Nov 2008 13:16:37 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 1/1] ftrace: improve document |
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* Steven Rostedt <rostedt@goodmis.org> wrote:
> > On Fri, 28 Nov 2008, walimis wrote: > > > > Signed-off-by: walimis <walimisdev@gmail.com> > > Reviewed-by: Ingo Molnar <mingo@elte.hu> > > Reviewed-by: Steven Rostedt <srostedt@redhat.com> > > Acked-by: Steven Rostedt <srostedt@redhat.com>
applied it to tip/tracing/ftrace, thanks guys! (Changed the commit log a bit, see the final commit below.)
Ingo
--------------> From c072c24975ec4f0ccfcb6f5c8a8040b6eb75ef8f Mon Sep 17 00:00:00 2001 From: walimis <walimisdev@gmail.com> Date: Fri, 28 Nov 2008 12:21:19 +0800 Subject: [PATCH] ftrace: improve documentation
Impact: extend documentation with notice of using wild cards correctly
We know that we can use wild cards to set set_ftrace_filter, but there's problem when using them naively such as:
echo h* > /debug/tracing/set_ftrace_filter
If there are files named with "h" prefix in current directory, echo "h*" will echo these filenames to set_ftrace_filter, not the intended "h*".
For example:
$ cat /debug/tracing/available_filter_functions |grep ^hr |wc -l 23 $ ls $ touch hraa hrdd $ ls hraa hrdd $ echo hr* > /debug/tracing/set_ftrace_filter $ cat /debug/tracing/set_ftrace_filter
No output in /debug/tracing/set_ftrace_filter!
If we use '' to escape wild cards, it works:
$ ls hraa hrdd $ echo "hr*" > /debug/tracing/set_ftrace_filter $ cat /debug/tracing/set_ftrace_filter |wc -l 23
This problem can lead to unexpected result if current directory has a lot of files.
Signed-off-by: walimis <walimisdev@gmail.com> Acked-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- Documentation/ftrace.txt | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/Documentation/ftrace.txt b/Documentation/ftrace.txt index de05042..803b131 100644 --- a/Documentation/ftrace.txt +++ b/Documentation/ftrace.txt @@ -1251,7 +1251,11 @@ These are the only wild cards which are supported. <match>*<match> will not work. - # echo hrtimer_* > /debug/tracing/set_ftrace_filter +Note: It is better to use quotes to enclose the wild cards, otherwise + the shell may expand the parameters into names of files in the local + directory. + + # echo 'hrtimer_*' > /debug/tracing/set_ftrace_filter Produces: @@ -1306,7 +1310,7 @@ Again, now we want to append. # echo sys_nanosleep > /debug/tracing/set_ftrace_filter # cat /debug/tracing/set_ftrace_filter sys_nanosleep - # echo hrtimer_* >> /debug/tracing/set_ftrace_filter + # echo 'hrtimer_*' >> /debug/tracing/set_ftrace_filter # cat /debug/tracing/set_ftrace_filter hrtimer_run_queues hrtimer_run_pending
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