Messages in this thread | | | Date | Tue, 30 Sep 2008 09:15:20 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] markers: let marker_debug as module parameter |
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* Lai Jiangshan <laijs@cn.fujitsu.com> wrote:
> if we want to enable marker debug output, we have to modify > the code and remake/reinstall the kernel in current code. > > this patch enable marker_debug to be set when kernel start. > > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> > --- > diff --git a/kernel/marker.c b/kernel/marker.c > index 9f76c4a..5d8404f 100644 > --- a/kernel/marker.c > +++ b/kernel/marker.c > @@ -28,8 +28,9 @@ > extern struct marker __start___markers[]; > extern struct marker __stop___markers[]; > > -/* Set to 1 to enable marker debug output */ > -static const int marker_debug; > +static int marker_debug; > +module_param(marker_debug, bool, 0); > +MODULE_PARM_DESC(marker_debug, "Set to 1 to enable marker debug output");
hm, in tip/master we already have ftrace_printk(), which allows such debug output to any of the active tracers. That is a far more useful way of debugging such things. See:
http://people.redhat.com/mingo/tip.git/README
and:
http://redhat.com/~mingo/sched-devel.git/readme-tracer.txt
note how much cleaner and more usable it will also become: no silly module flags or recompilation to activate this debug output, and no debug clutter in the syslog.
if you enable tracing in the 'nop' tracer then only the ftrace_printk()'s will be printed, no other trace entries.
Ingo
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