Re: [PATCH 0/2] Objpool performance improvements

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

Hi Andrii,

On Wed, 24 Apr 2024 14:52:12 -0700
Andrii Nakryiko <andrii@kernel.org> wrote:

> Improve objpool (used heavily in kretprobe hot path) performance with two
> improvements:
>   - inlining performance critical objpool_push()/objpool_pop() operations;
>   - avoiding re-calculating relatively expensive nr_possible_cpus().

Thanks for optimizing objpool. Both looks good to me.

BTW, I don't intend to stop this short-term optimization attempts,
but I would like to ask you check the new fgraph based fprobe 
(kretprobe-multi)[1] instead of objpool/rethook.

[1] https://lore.kernel.org/all/171318533841.254850.15841395205784342850.stgit@devnote2/

I'm considering to obsolete the kretprobe (and rethook) with fprobe
and eventually remove it. Those have similar feature and we should
choose safer one.

Thank you,

> 
> These opportunities were found when benchmarking and profiling kprobes and
> kretprobes with BPF-based benchmarks. See individual patches for details and
> results.
> 
> Andrii Nakryiko (2):
>   objpool: enable inlining objpool_push() and objpool_pop() operations
>   objpool: cache nr_possible_cpus() and avoid caching nr_cpu_ids
> 
>  include/linux/objpool.h | 105 +++++++++++++++++++++++++++++++++++--
>  lib/objpool.c           | 112 +++-------------------------------------
>  2 files changed, 107 insertions(+), 110 deletions(-)
> 
> -- 
> 2.43.0
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>