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.

Thanks,
Namhyung


Namhyung Kim (4):
  perf tools: Don't set attr.exclude_guest by default
  perf tools: Simplify evsel__add_modifier()
  perf stat: Add --exclude-guest option
  perf tools: Do not set exclude_guest for precise_ip

 tools/perf/Documentation/perf-stat.txt     |  7 +++++
 tools/perf/builtin-kvm.c                   |  1 +
 tools/perf/builtin-stat.c                  |  2 ++
 tools/perf/tests/attr/test-record-dummy-C0 |  2 +-
 tools/perf/tests/parse-events.c            | 30 ++++++++++------------
 tools/perf/util/evsel.c                    |  5 +---
 tools/perf/util/parse-events.c             |  6 +----
 tools/perf/util/util.c                     | 10 ++++++--
 tools/perf/util/util.h                     |  3 +++
 9 files changed, 37 insertions(+), 29 deletions(-)

-- 
2.46.0.469.g59c65b2a67-goog

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?