Messages in this thread Patch in this message | | | Date | Mon, 12 Oct 2009 11:09:33 +0200 | Subject | Re: [PATCH] ftrace: add kernel command line graph function filtering | From | Frédéric Weisbecker <> |
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2009/10/12 Stefan Assmann <sassmann@redhat.com>: > From 894e934e782ddaa33eb6d156d8326cdf479b5f62 Mon Sep 17 00:00:00 2001 > From: Stefan Assmann <sassmann@redhat.com> > Date: Mon, 12 Oct 2009 09:11:47 +0200 > Subject: [PATCH] ftrace: add kernel command line graph function filtering > > Add a command line parameter to allow limiting the function graphs that > are traced on boot up, when ftrace=function_graph is specified. > > This patch adds the following command line option: > ftrace_graph_filter=function-list
If we use this parameter, we undoubtedly want to launch the function graph tracer. I'd then suggest to arm ftrace=function_graph automatically if we have ftrace_graph_filter set.
> > Where function-list is a comma separated list of functions to filter. > > Signed-off-by: Stefan Assmann <sassmann@redhat.com> > --- > Documentation/kernel-parameters.txt | 9 ++++++++- > kernel/trace/ftrace.c | 34 ++++++++++++++++++++++++++++++++++ > 2 files changed, 42 insertions(+), 1 deletions(-) > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 9107b38..144eb83 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -771,7 +771,14 @@ and is between 256 and 4096 characters. It is defined in the file > tracer at boot up. function-list is a comma separated > list of functions. This list can be changed at run > time by the set_ftrace_filter file in the debugfs > - tracing directory. > + tracing directory. > + > + ftrace_graph_filter=[function-list] > + [FTRACE] Limit the functions traced by the function > + graph tracer at boot up. function-list is a comma > + separated list of functions. This list can be changed > + at run time by the set_graph_function file in the > + debugfs tracing directory.
May be you should use a more detailed definition of this parameter. Limiting a function traced by the function graph tracer is ambiguous.
It means we can have either:
function_to_trace();
or:
function_to_trace() { foo() { bar(); } }
We want the second thing. May be instead you can write:
"Limit the top level callers functions traced by the function graph tracer at boot up."
Otherwise, looks good to me:
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Thanks.
> ftrace_notrace=[function-list] > [FTRACE] Do not trace the functions specified in > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c > index 3724756..a5cae5c 100644 > --- a/kernel/trace/ftrace.c > +++ b/kernel/trace/ftrace.c > @@ -78,6 +78,10 @@ ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub; > ftrace_func_t __ftrace_trace_function __read_mostly = ftrace_stub; > ftrace_func_t ftrace_pid_function __read_mostly = ftrace_stub; > > +#ifdef CONFIG_FUNCTION_GRAPH_TRACER > +static int ftrace_set_func(unsigned long *array, int *idx, char *buffer); > +#endif > + > static void ftrace_list_func(unsigned long ip, unsigned long parent_ip) > { > struct ftrace_ops *op = ftrace_list; > @@ -2302,6 +2306,7 @@ void ftrace_set_notrace(unsigned char *buf, int len, int reset) > #define FTRACE_FILTER_SIZE COMMAND_LINE_SIZE > static char ftrace_notrace_buf[FTRACE_FILTER_SIZE] __initdata; > static char ftrace_filter_buf[FTRACE_FILTER_SIZE] __initdata; > +static char ftrace_graph_buf[FTRACE_FILTER_SIZE] __initdata; > > static int __init set_ftrace_notrace(char *str) > { > @@ -2317,6 +2322,31 @@ static int __init set_ftrace_filter(char *str) > } > __setup("ftrace_filter=", set_ftrace_filter); > > +#ifdef CONFIG_FUNCTION_GRAPH_TRACER > +static int __init set_graph_function(char *str) > +{ > + strncpy(ftrace_graph_buf, str, FTRACE_FILTER_SIZE); > + return 1; > +} > +__setup("ftrace_graph_filter=", set_graph_function); > + > +static void __init set_ftrace_early_graph(char *buf) > +{ > + int ret; > + char *func; > + > + while (buf) { > + func = strsep(&buf, ","); > + /* we allow only one expression at a time */ > + ret = ftrace_set_func(ftrace_graph_funcs, &ftrace_graph_count, > + func); > + if (ret) > + printk(KERN_DEBUG "ftrace: function %s not " > + "traceable\n", func); > + } > +} > +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ > + > static void __init set_ftrace_early_filter(char *buf, int enable) > { > char *func; > @@ -2333,6 +2363,10 @@ static void __init set_ftrace_early_filters(void) > set_ftrace_early_filter(ftrace_filter_buf, 1); > if (ftrace_notrace_buf[0]) > set_ftrace_early_filter(ftrace_notrace_buf, 0); > +#ifdef CONFIG_FUNCTION_GRAPH_TRACER > + if (ftrace_graph_buf[0]) > + set_ftrace_early_graph(ftrace_graph_buf); > +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ > } > > static int > -- > 1.6.2.5 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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