On Fri, 24 Jul 2020 13:40:20 -0400 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > On Fri, 24 Jul 2020 13:36:56 -0400 > Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > > > Which BTW, is supported by the following architectures: > > x86 Ah, you can lose support on x86 if you don't enable DYNAMIC_FTRACE, which is stupid to do. I only enabled disabling of DYNAMIC_FTRACE on x86 to test it, as not all architectures have it, and I currently only test on x86. Without DYNAMIC_FTRACE enabled, you *always* call into the ftrace infrastructure for *every* function. This adds something like 15 to 20% overhead to the kernel. Did I say it was stupid to do so? If you are going through all this work because some randconfig causes this warning because it enables CONFIG_FUNCTION_TRACER but without DYNAMIC_FTRACE enabled, then I strongly suggest you start spending your time elsewhere, because it will be a big NAK on my part to add all this intrusive code for a config used only for debugging the non DYNAMIC_FTRACE case. -- Steve
