Re: [PATCH 4/5 v3] tracing/core: drop the old ftrace_printk implementation in favour of ftrace_bprintk

[Ingo Molnar <mingo@elte.hu>]

* Ingo Molnar <mingo@elte.hu> wrote:

> 
> * Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> > 
> > 
> > On Fri, 6 Mar 2009, Frederic Weisbecker wrote:
> > 
> > > Impact: faster and lighter tracing
> > > 
> > > Now that we have ftrace_bprintk() which is faster and consume lesser
> > > memory than ftrace_printk() and has the same purpose, we can now drop
> > > the old implementation in favour of the binary one from ftrace_bprintk(),
> > > which means we move all the implementation of ftrace_bprintk() to
> > > ftrace_printk(), so the Api doesn't change except that we must now use
> > > trace_seq_bprintk() to print the TRACE_PRINT entries.
> > > 
> > > Some changes result of this:
> > > 
> > > - Previously, ftrace_bprintk depended of a single tracer and couldn't
> > >   work without. This tracer has been dropped and the whole implementation
> > >   of ftrace_printk() (like the module formats management) is now integrated
> > >   in the tracing core (comes with CONFIG_TRACING), though we keep the file
> > >   trace_printk (previously trace_bprintk.c) where we can find the module
> > >   management. Thus we don't overflow trace.c
> > > 
> > > - changes some parts to use trace_seq_bprintk() to print TRACE_PRINT entries.
> > > 
> > > - change a bit ftrace_printk/ftrace_vprintk macros to support non-builtin formats
> > >   constants, and fix 'const' qualifiers warnings. But this is all transparent for
> > >   developers.
> > > 
> > > - etc...
> > > 
> > > V2:
> > > 
> > > - Rebase against last changes
> > > - Fix mispell on the changelog
> > > 
> > > V3:
> > > 
> > > - Rebase against last changes (moving ftrace_printk() to kernel.h)
> > > 
> > > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> > 
> > Very nice Frederic!
> > 
> > For some reason I'm still missing patch 1. Perhaps it decided to take the
> > scenic route ;-)
> > 
> > > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> > > index 0f5077f..6140922 100644
> > > --- a/kernel/trace/trace.h
> > > +++ b/kernel/trace/trace.h
> > > @@ -20,7 +20,6 @@ enum trace_type {
> > >  	TRACE_WAKE,
> > >  	TRACE_STACK,
> > >  	TRACE_PRINT,
> > > -	TRACE_BPRINTK,
> > >  	TRACE_SPECIAL,
> > >  	TRACE_MMIO_RW,
> > >  	TRACE_MMIO_MAP,
> > > @@ -120,16 +119,10 @@ struct userstack_entry {
> > >   */
> > >  struct print_entry {
> > >  	struct trace_entry	ent;
> > > -	unsigned long		ip;
> > > +	unsigned long 		ip;
> > >  	int			depth;
> > > -	char			buf[];
> > > -};
> > > -
> > 
> > 
> > Note, this is going to break my recent patch that exports the 
> > internal ftrace events. That's OK, I'll fix it after Ingo 
> > pulls it in.
> > 
> > Ingo,
> > 
> > Would you prefer that I pull these patches in and then fix the 
> > code, and let you pull it from me?
> 
> i've put them into a separate branch forked off 
> tip:tracing/ftrace: tip:tracing/printk. The two vsprintf 
> patches are in tip:core/printk and merged into tracing/ftrace.
> 
> You can thus apply your current enhancements without any 
> interaction with me - and merge tracing/printk into the 
> tip:tracing/ftrace branch on your own schedule, ok?

ah - i misunderstood - i see that it interacts with your commits 
from last night.

I've excluded tip:tracing/printk from tip:master for now and 
will let you guys fix it up when you have time for it.

	Ingo