• Steven Rostedt (Red Hat)'s avatar
    tracing: Add trace_puts() for even faster trace_printk() tracing · 09ae7234
    Steven Rostedt (Red Hat) authored
    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: default avatarSteven Rostedt <rostedt@goodmis.org>
trace.h 29.5 KB