Re: [GIT PULL] Clang feature updates for v5.14-rc1

[Linus Torvalds]

On Tue, Jun 29, 2021 at 2:27 PM Nick Desaulniers
<ndesaulniers@xxxxxxxxxx> wrote:
>
> Right now we're having trouble with hardware performance counters on
> non-intel chips; I don't think we have working LBR equivalents on AMD
> until zen3, and our ETM based samples on ARM are hung up on a few last
> minute issues requiring new hardware (from multiple different chipset
> vendors).

I agree that perf profiling works best on Intel. The AMD perf side
works ok in Zen 2 from what I've seen, but needs to be a full-system
profile ("perf record -a") to use the better options, and ARM is..

But with x86 ranging from "excellent" to "usable", and ARM hopefully
being at least close to getting better proper profile data, I really
think it's the way forward, with instrumentation being a band-aid at
best.

             Linus