Re: [RFC/PATCH 0/4] perf tools: Do not set attr.exclude_guest by default (v1)

[Peter Zijlstra]

On Sun, Sep 01, 2024 at 06:46:17PM -0700, Namhyung Kim wrote:
> Hello,
> 
> I found perf tools set exclude_guest bit inconsistently.  It used to
> set the bit but now the default event for perf record doesn't.  So I'm
> wondering why we want the bit in the first place.
> 
> Actually it's not good for PMUs don't support any exclusion like AMD
> IBS because it disables new features after the exclude_guest due to
> the missing feature detection logic.
> 
> AFAIK it doesn't matter for the most cases but perf kvm.  If users
> need to set the bit, they can still use :H modifier.  Please let me
> know if it's ok for you.

IIRc the point of setting exclude_guest by default was so that default
perf keeps working in the precense of that PMU pass through mess, no?