Messages in this thread | | | Subject | Re: [PATCH] tracing: add trace console | From | Johannes Berg <> | Date | Wed, 16 Nov 2011 21:12:59 +0100 |
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On Wed, 2011-11-16 at 14:57 -0500, Steven Rostedt wrote: > On Wed, 2011-11-16 at 19:33 +0100, Johannes Berg wrote: > > On Wed, 2011-11-16 at 12:00 -0500, Steven Rostedt wrote: > > > On Wed, 2011-11-16 at 17:45 +0100, Johannes Berg wrote: > > > > > > > I briefly looked at it just after writing the email, but quickly got > > > > lost in printk.c because of the multi-line handling it has. We could > > > > instead trace each call to printk(), so the multi-line stuff would end > > > > up in multiple events, but all of that code is too much vodoo for me :) > > > > > > Here's what can go into printk.c: > > > > > > diff --git a/kernel/printk.c b/kernel/printk.c > > > index 1455a0d..4b8445a 100644 > > > --- a/kernel/printk.c > > > +++ b/kernel/printk.c > > > @@ -542,6 +542,7 @@ MODULE_PARM_DESC(ignore_loglevel, "ignore loglevel setting, to" > > > static void _call_console_drivers(unsigned start, > > > unsigned end, int msg_log_level) > > > { > > > + trace_console(&LOG_BUF(start), end - start); > > > if ((msg_log_level < console_loglevel || ignore_loglevel) && > > > console_drivers && start != end) { > > > if ((start & LOG_BUF_MASK) > (end & LOG_BUF_MASK)) { > > > > > > > > > And then you can make a TRACE_EVENT(console) that takes a buffer and a > > > len, and write that to the ring buffer. > > > > Yes, of course, but if we're going to modify the code then I thought we > > should probably trace everything independent of the console printk > > level. > > > > This will trace everything independent from the console level. Noticed > that I put the tracepoint before the msg_log_level is checked.
D'oh, right. Yeah that seems good. Too bad I discarded my previous attempt already :)
johannes
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