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


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?

-- Steve



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