Re: [PATCH] x86/alternatives: remove false sharing in poke_int3_handler()

[Eric Dumazet]

On Mon, Mar 24, 2025 at 8:16 AM Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>
>
> * Eric Dumazet <edumazet@xxxxxxxxxx> wrote:
>
> > > What's the adversarial workload here? Spamming bpf_stats_enabled on all
> > > CPUs in parallel? Or mixing it with some other text_poke_bp_batch()
> > > user if bpf_stats_enabled serializes access?
>             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> > > Does anything undesirable happen in that case?
> >
> > The case of multiple threads trying to flip bpf_stats_enabled is
> > handled by bpf_stats_enabled_mutex.
>
> So my suggested workload wasn't adversarial enough due to
> bpf_stats_enabled_mutex: how about some other workload that doesn't
> serialize access to text_poke_bp_batch()?

Do you have a specific case in mind that I can test on these big platforms ?

text_poke_bp_batch() calls themselves are serialized by text_mutex, it
is not clear what you are looking for.

Thanks.