Re: [PATCH] signal: Allow RT tasks to cache one sigqueue struct

[Thomas Gleixner]

On Thu, Mar 11 2021 at 00:56, Thomas Gleixner wrote:
> Rant aside, there is no massive benefit of doing that caching in
> general, but there is not much of a downside either and for particular
> use cases it's useful even outside of PREEMPT_RT.
>
> IMO, having it there unconditionally is better than yet another special
> cased hackery.

Just did some micro instrumentation to measure the time spent in
__sigqueue_alloc/free() with and without the caching.

Unsurprisingly that results in a time reduction of ~67% saving about 3us
per alloc/free pair. Not hugely relevant for a kernel build but for
anything which is signal heavy it'll make an difference.

Thanks,

        tglx