[Patch RFC 0/2] tracing: allow disabling compilation of specific trace systems

From: Tal Shorer
Date: Mon Jun 08 2015 - 15:05:56 EST


Currently, enabling CONFIG_TRACING on a system comes as all-or-nothing: either
tracepoints for all subsystems are compiled (with CONFIG_TRACING) or none of
them do (without it).

This caused me an unacceptable performance penalty (obviously SOME penalty was
expected, but not one so severe) which made me revert the changes in
configuration.

The first patch in this series modifies the files that actually define the
tracepoint to look for a preprocessor macro NOTRACE and define nops (as if
CONFIG_TRACING was not set) instead of them.

The second patch provides an example of how I see this working, with the gpio
subsystem as the example for absolutely no reason.
If this idea is deemed worth the time by the community, I'll create patches for
the other subsystems.

Tal Shorer (2):
tracing: allow disabling compilation of specific trace systems
tracing: gpio: add Kconfig option for enabling/disabling trace events

drivers/gpio/Kconfig | 6 ++++++
include/linux/tracepoint.h | 6 +++---
include/trace/define_trace.h | 2 +-
include/trace/events/gpio.h | 4 ++++
4 files changed, 14 insertions(+), 4 deletions(-)

--
2.2.2

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