Re: [PATCH] tracing: annotate emit_log_char() notrace
From: Frederic Weisbecker
Date: Thu May 28 2009 - 10:17:01 EST
On Wed, May 27, 2009 at 05:00:44PM +0200, Thomas Gleixner wrote:
> printk calls emit_log_char() in a loop which is cluttering the trace
> buffer. Make it notrace.
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Does it produce that much annoying traces?
I mean, printk() are usually rare events.
Do you have a particular debugging workflow that makes this
function invasive in the trace?
May be it's because you are debugging using ftrace and other
debugging options that use a lot of printk()
In such case, it would indeed be good to apply this patch.
> kernel/printk.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> Index: linux-2.6-tip/kernel/printk.c
> --- linux-2.6-tip.orig/kernel/printk.c
> +++ linux-2.6-tip/kernel/printk.c
> @@ -499,7 +499,7 @@ static void call_console_drivers(unsigne
> _call_console_drivers(start_print, end, msg_level);
> -static void emit_log_char(char c)
> +static void notrace emit_log_char(char c)
> LOG_BUF(log_end) = c;
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