Re: [PATCH bpf-next v2] bpf: Cache the last valid build_id.

[Song Liu]

On Wed, Feb 23, 2022 at 4:05 PM Hao Luo <haoluo@xxxxxxxxxx> wrote:
>
> For binaries that are statically linked, consecutive stack frames are
> likely to be in the same VMA and therefore have the same build id.
> As an optimization for this case, we can cache the previous frame's
> VMA, if the new frame has the same VMA as the previous one, reuse the
> previous one's build id. We are holding the MM locks as reader across
> the entire loop, so we don't need to worry about VMA going away.
>
> Tested through "stacktrace_build_id" and "stacktrace_build_id_nmi" in
> test_progs.
>
> Suggested-by: Greg Thelen <gthelen@xxxxxxxxxx>
> Signed-off-by: Hao Luo <haoluo@xxxxxxxxxx>

Nice optimization!

Acked-by: Song Liu <songliubraving@xxxxxx>