On Mon, Oct 9, 2023 at 10:14 AM Yajun Deng <yajun.deng@xxxxxxxxx> wrote: > > > On 2023/10/9 15:53, Eric Dumazet wrote: > > On Mon, Oct 9, 2023 at 5:07 AM Yajun Deng <yajun.deng@xxxxxxxxx> wrote: > > > >> 'this_cpu_read + this_cpu_write' and 'pr_info + this_cpu_inc' will make > >> the trace work well. > >> > >> They all have 'pop' instructions in them. This may be the key to making > >> the trace work well. > >> > >> Hi all, > >> > >> I need your help on percpu and ftrace. > >> > > I do not think you made sure netdev_core_stats_inc() was never inlined. > > > > Adding more code in it is simply changing how the compiler decides to > > inline or not. > > > Yes, you are right. It needs to add the 'noinline' prefix. The > disassembly code will have 'pop' > > instruction. > The function was fine, you do not need anything like push or pop. The only needed stuff was the call __fentry__. The fact that the function was inlined for some invocations was the issue, because the trace point is only planted in the out of line function.
