Re: [PATCH 0/2] tracing: Move trace_printk.h out of kernel.h

"Christophe Leroy (CS GROUP)" <[email protected]> Mon, 22 Jun 2026 10:05:13 +0200

Newsgroups	gmane.comp.freedesktop.xorg.drivers.intel,gmane.linux.kernel,gmane.linux.documentation,gmane.linux.kbuild.devel,gmane.linux.ports.ppc64.devel,gmane.comp.video.dri.devel,gmane.linux.ports.arm.kernel,gmane.linux.drivers.rdma,gmane.linux.usb.general,gmane.comp.file-systems.ext4,gmane.linux.nfs,gmane.comp.emulators.kvm.devel
Message-ID	<[email protected]>


Le 21/06/2026 à 11:34, Steven Rostedt a écrit :
> There's been complaints about trace_printk() being defined in kernel.h as it
> can increase the compilation time. As it is only used by some developers for
> debugging purposes, it should not be in kernel.h causing lots of wasted CPU
> cycles for those that do not ever care about it.

Do we have a measurement of the increased compilation time ?

Christophe

> 
> Instead, add a CONFIG_TRACE_PRINTK_DEBUGGING option that developers that do
> use it can set and not have to always remember to add #include <linux/trace_printk.h>
> to the files they add trace_printk() while debugging. It also means that
> those that do not have that config set will not have to worry about wasted
> CPU cycles as it is only include in the CFLAGS when the option is set, and
> its completely ignored otherwise.
> 
> Steven Rostedt (2):
>        tracing: Move non-trace_printk prototypes back to kernel.h
>        tracing: Add CONFIG_TRACE_PRINTK_DEBUGGING to clean up kernel.h
> 
> ----
>   .../driver_development_debugging_guide.rst         |  2 +-
>   Makefile                                           |  5 +++++
>   arch/powerpc/kvm/book3s_xics.c                     |  1 +
>   drivers/gpu/drm/i915/gt/intel_gtt.h                |  1 +
>   drivers/gpu/drm/i915/i915_gem.h                    |  1 +
>   drivers/hwtracing/stm/dummy_stm.c                  |  4 ++++
>   drivers/infiniband/hw/hfi1/trace_dbg.h             |  1 +
>   drivers/usb/early/xhci-dbc.c                       |  1 +
>   fs/ext4/inline.c                                   |  1 +
>   include/linux/kernel.h                             | 19 ++++++++++++++++++-
>   include/linux/sunrpc/debug.h                       |  1 +
>   include/linux/trace_printk.h                       | 22 +++-------------------
>   kernel/trace/Kconfig                               | 10 ++++++++++
>   kernel/trace/ring_buffer_benchmark.c               |  1 +
>   kernel/trace/trace.h                               |  1 +
>   samples/fprobe/fprobe_example.c                    |  1 +
>   samples/ftrace/ftrace-direct-modify.c              |  1 +
>   samples/ftrace/ftrace-direct-multi-modify.c        |  1 +
>   samples/ftrace/ftrace-direct-multi.c               |  2 +-
>   samples/ftrace/ftrace-direct-too.c                 |  2 +-
>   samples/ftrace/ftrace-direct.c                     |  2 +-
>   21 files changed, 56 insertions(+), 24 deletions(-)
>