tjh.dev
perf tools: Don't set attr.exclude_guest by default
The exclude_guest in the event attribute is to limit profiling in the
host environment. But I'm not sure why we want to set it by default
cause we don't care about it in most cases and I feel like it just
makes new PMU implementation complicated.
Of course it's useful for perf kvm command so I added the
exclude_GH_default variable to preserve the old behavior for perf kvm
and other commands like perf record and stat won't set the exclude bit.
This is helpful for AMD IBS case since having exclude_guest bit will
clear new feature bit due to the missing feature check logic.
$ sysctl kernel.perf_event_paranoid
kernel.perf_event_paranoid = 0
$ perf record -W -e ibs_op// -vv true 2>&1 | grep switching
switching off PERF_FORMAT_LOST support
switching off weight struct support
switching off bpf_event
switching off ksymbol
switching off cloexec flag
switching off mmap2
switching off exclude_guest, exclude_host
Intestingly, I found it sets the exclude_bit if "u" modifier is used.
I don't know why but it's neither intuitive nor consistent. Let's
remove the bit there too.
Reviewed-by: Ian Rogers <irogers@google.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Reviewed-by: Ravi Bangoria <ravi.bangoria@amd.com>
Acked-by: Kan Liang <kan.liang@linux.intel.com>
Cc: James Clark <james.clark@arm.com>
Cc: Atish Patra <atishp@atishpatra.org>
Cc: Mingwei Zhang <mizhang@google.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lore.kernel.org/r/20241016062359.264929-3-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>