Re: [PATCH 2/8] tracing: do not trace kernel_text_address()

[Andy Chiu]

On Thu, Jun 13, 2024 at 9:32 PM Steven Rostedt  wrote:
>
> On Thu, 13 Jun 2024 15:11:07 +0800
> Andy Chiu  wrote:
>
> > kernel_text_address() and __kernel_text_address() are called in
> > arch_stack_walk() of riscv. This results in excess amount of un-related
> > traces when the kernel is compiled with CONFIG_TRACE_IRQFLAGS. The
> > situation worsens when function_graph is active, as it calls
> > local_irq_save/restore in each function's entry/exit. This patch adds
> > both functions to notrace, so they won't show up on the trace records.
>
> I rather not add notrace just because something is noisy.
>
> You can always just add:
>
>  echo '*kernel_text_address' > /sys/kernel/tracing/set_ftrace_notrace
>
> and achieve the same result.

Sounds good, I am going to drop this patch for the next revision

>
> -- Steve

Thanks,
Andy

Re: [PATCH 2/8] tracing: do not trace kernel_text_address()

[Steven Rostedt]

On Thu, 13 Jun 2024 15:11:07 +0800
Andy Chiu  wrote:

> kernel_text_address() and __kernel_text_address() are called in
> arch_stack_walk() of riscv. This results in excess amount of un-related
> traces when the kernel is compiled with CONFIG_TRACE_IRQFLAGS. The
> situation worsens when function_graph is active, as it calls
> local_irq_save/restore in each function's entry/exit. This patch adds
> both functions to notrace, so they won't show up on the trace records.

I rather not add notrace just because something is noisy.

You can always just add:

 echo '*kernel_text_address' > /sys/kernel/tracing/set_ftrace_notrace

and achieve the same result.

-- Steve

[PATCH 2/8] tracing: do not trace kernel_text_address()

[Andy Chiu]

kernel_text_address() and __kernel_text_address() are called in
arch_stack_walk() of riscv. This results in excess amount of un-related
traces when the kernel is compiled with CONFIG_TRACE_IRQFLAGS. The
situation worsens when function_graph is active, as it calls
local_irq_save/restore in each function's entry/exit. This patch adds
both functions to notrace, so they won't show up on the trace records.

Signed-off-by: Andy Chiu 
---
 kernel/extable.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/extable.c b/kernel/extable.c
index 71f482581cab..d03fa462fa8b 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -74,7 +74,7 @@ int notrace core_kernel_text(unsigned long addr)
return 0;
 }
 
-int __kernel_text_address(unsigned long addr)
+int notrace __kernel_text_address(unsigned long addr)
 {
if (kernel_text_address(addr))
return 1;
@@ -91,7 +91,7 @@ int __kernel_text_address(unsigned long addr)
return 0;
 }
 
-int kernel_text_address(unsigned long addr)
+int notrace kernel_text_address(unsigned long addr)
 {
bool no_rcu;
int ret = 1;

-- 
2.43.0