On Thu, Nov 21, 2024 at 4:17 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> 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.
