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tracing: Add trace_puts() for even faster trace_printk() tracing

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The trace_printk() is extremely fast and is very handy as it can be
used in any context (including NMIs!). But it still requires scanning
the fmt string for parsing the args. Even the trace_bprintk() requires
a scan to know what args will be saved, although it doesn't copy the
format string itself.

Several times trace_printk() has no args, and wastes cpu cycles scanning
the fmt string.

Adding trace_puts() allows the developer to use an even faster
tracing method that only saves the pointer to the string in the
ring buffer without doing any format parsing at all. This will
help remove even more of the "Heisenbug" effect, when debugging.

Also fixed up the F_printk()s for the ftrace internal bprint and print events.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2013-03-08 21:02:34 -05:00 • committed by Steven Rostedt
parent 153e8ed913
commit 09ae72348e
6 changed files with 214 additions and 5 deletions
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2
kernel/trace/trace_output.h
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@ -4,6 +4,8 @@
#include <linux/trace_seq.h>
#include "trace.h"
extern enum print_line_t
trace_print_bputs_msg_only(struct trace_iterator *iter);
extern enum print_line_t
trace_print_bprintk_msg_only(struct trace_iterator *iter);
extern enum print_line_t