Re: [PATCH v7 18/43] instrumented.h: add KMSAN support

Marco Elver
2022-10-21T07:38:11Z

On Thu, 20 Oct 2022 at 23:39, youling 257 <youling257@gmail.com> wrote:
>
> PerfTop: 8253 irqs/sec kernel:75.3% exact: 100.0% lost: 0/0 drop:
> 0/17899 [4000Hz cycles], (all, 8 CPUs)
> ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> 14.87% [kernel] [k] 0xffffffff941d1f37
> 6.71% [kernel] [k] 0xffffffff942016cf
>
> what is 0xffffffff941d1f37?

You need to build with debug symbols:
CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y

Then it'll show function names.

> 2022-10-21 14:16 GMT+08:00, Marco Elver <elver@google.com>:
> > On Thu, 20 Oct 2022 at 22:55, youling 257 <youling257@gmail.com> wrote:
> >>
> >> How to use perf tool?
> >
> > The simplest would be to try just "perf top" - and see which kernel
> > functions consume most CPU cycles. I would suggest you compare both
> > kernels, and see if you can spot a function which uses more cycles% in
> > the problematic kernel.
> >