On Wed, 24 Jun 2026 10:32:25 -0400 Steven Rostedt <[email protected]> wrote:
> On Wed, 24 Jun 2026 11:11:52 +0100 > David Laight <[email protected]> wrote: > > > That is all about changes to the file causing everything to be rebuilt, > > not the contents of the file slowing down builds. > > I guess I should say it better. It causes more build time if that file > changes. That's what I meant. I update the wording to say: > > There have been complaints about trace_printk.h causing more build time > for being in kernel.h it if changes. There is also an effort to clean up > kernel.h to have it not include unneeded header files. Move trace_printk.h > out of kernel.h and place it in the headers and C files that use it. > > > > The part you are moving out of normal builds is just a few #defines. > > They won't have a significant effect on build times either. > > > > So there is no point splitting out trace_controls.h. > > That is a completely different reason. trace_printk.h is about > trace_printk() usage. The stuff split out into trace_controls.h have > nothing to do with trace_printk()s. True, but every header file costs extra time to open. That could easily be more that the cost of parsing it (ok hand waving!). With a long list of -I parameters just finding a file costs because of all the failed opens. I've just knocked it out of kernel.h, had to fix: rcu.h linux/ftrace.h to make my 'normal' kernel build. Lots of stuff includes the latter. David > > -- Steve >
