On Thu, Nov 21, 2024 at 4:17 AM Peter Zijlstra <pet...@infradead.org> wrote:
>
> On Wed, Nov 20, 2024 at 04:07:38PM -0800, Andrii Nakryiko wrote:
>
> > USDTs are meant to be "transparent" to the surrounding code and they
> > don't mark any clobbered registers. Technically it could be added, but
> > I'm not a fan of this.
>
> Sure. Anyway, another thing to consider is FRED, will all of this still
> matter once that lands? If FRED gets us INT3 performance close to what
> SYSCALL has, then all this work will go unused.

afaik not a single cpu in the datacenter supports FRED while
uprobe overhead is real.
imo it's worth improving performance today for existing cpus.
I suspect arm64 might benefit too. Even if arm hw does the same
amount of work for trap vs syscall the sw overhead of handling
trap is different.
I suspect that equation will apply to future FRED cpus too.

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