Re: [PATCH perf-tools-next v12 06/10] perf ftrace: Support display of inlined functions in function graph tracer

[Aaron Tomlin]

On Tue, Nov 03, 2026 at 11:46:49PM -0800, Namhyung Kim wrote:
> > > > +#define FTRACE_MAX_INLINES 32
> > > 
> > > Isn't 32 too big?  I guess 8 would be enough..
> > 
> > No, 8 is not enough in practice. I will prefer to keep 32.
> > For instance, after a -O2 kernel build:
> > 
> > ❯ addr2line -f -i -e vmlinux 0xffffffff816916e9
> >       __do_trace_rss_stat
> >       include/trace/events/kmem.h:427 (discriminator 20)
> >       trace_rss_stat
> >       include/trace/events/kmem.h:427 (discriminator 20)
> >       mm_trace_rss_stat
> >       mm/memory.c:169 (discriminator 20)
> >       add_mm_counter
> >       include/linux/mm.h:3469 (discriminator 20)
> >       add_mm_rss_vec
> >       mm/memory.c:492 (discriminator 20)
> >       zap_pte_range
> >       mm/memory.c:2087 (discriminator 20)
> >       zap_pmd_range
> >       mm/memory.c:2151 (discriminator 20)
> >       zap_pud_range
> >       mm/memory.c:2179 (discriminator 20)
> >       zap_p4d_range
> >       mm/memory.c:2200 (discriminator 20)
> >       __zap_vma_range
> >       mm/memory.c:2240 (discriminator 20)
> > 
> > Another example:
> > 
> > ❯ addr2line -f -i -e vmlinux 0xffffffff821c34af
> >       constant_test_bit
> >       arch/x86/include/asm/bitops.h:202
> >       arch_test_bit
> >       arch/x86/include/asm/bitops.h:232
> >       _test_bit
> >       include/asm-generic/bitops/instrumented-non-atomic.h:142
> >       test_ti_thread_flag
> >       include/linux/thread_info.h:133
> >       test_tsk_thread_flag
> >       include/linux/sched.h:2102
> >       task_sigpending
> >       include/linux/sched/signal.h:384
> >       fatal_signal_pending
> >       include/linux/sched/signal.h:406
> >       ptrace_report_syscall
> >       include/linux/ptrace.h:427
> >       ptrace_report_syscall_exit
> >       include/linux/ptrace.h:477
> >       arch_ptrace_report_syscall_exit
> >       include/linux/entry-common.h:233
> >       syscall_exit_work
> >       include/linux/entry-common.h:266
> >       syscall_exit_to_user_mode_work
> >       include/linux/entry-common.h:297
> >       syscall_exit_to_user_mode
> >       include/linux/entry-common.h:334
> >       do_syscall_64
> >       arch/x86/entry/syscall_64.c:89
> 
> Oh, indeed.  Thanks for providing this!
> 
> Namhyung

No problem!

Kind regards,
-- 
Aaron Tomlin