Re: [PATCH 0/4] perf c2c: Detect shared memory cachelines

[Namhyung Kim <namhyung@kernel.org>]

Hello,

On Mon, Oct 06, 2025 at 07:57:06PM +0200, Michael Petlan wrote:
> Hello.
> 
> Currently, perf-c2c tool has no means to discover a scenario when
> there is a single cacheline in shared memory, which is mapped to
> multiple different virtual addresses.
> 
> This patchset adds a mechanism to detect this. First, an "S" flag
> suggests that such scenario may occur (a cacheline in shared memory
> is captured). Additinally, another option is added (--detect-shm),
> which zooms to the SHM cacheline and shows the physical addresses too.

Any example output?  With a test program would be ideal.

Thanks,
Namhyung

> 
> Jiri Olsa has drafted this feature some time ago. I have rebased it
> to current kernel repository shape and reworked several things in it
> after some discussions with Joe Mario.
> 
> Thanks for thoughts and comments.
> 
> Michael
> 
> 
> Michael Petlan (4):
>   perf tools: Remove /SYSV from no_dso maps
>   perf c2c: Add shared mem flag
>   perf c2c: Add map name for cacheline
>   perf c2c report: Add --detect-shm option
> 
>  tools/perf/builtin-c2c.c    | 178 +++++++++++++++++++++++++++++-------
>  tools/perf/builtin-inject.c |   4 +-
>  tools/perf/util/map.c       |   5 +-
>  tools/perf/util/map.h       |   6 +-
>  4 files changed, 154 insertions(+), 39 deletions(-)
> 
> -- 
> 2.47.3
>