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    SubjectRe: [PATCH] perf parse-events: Set exclude_guest for user-space counting
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    Hi Like,

    On 8/12/2020 9:02 PM, Like Xu wrote:
    > On 2020/8/12 20:15, Arnaldo Carvalho de Melo wrote:
    >> Em Wed, Aug 12, 2020 at 02:59:53PM +0800, Jin Yao escreveu:
    >>> Currently if we run 'perf record -e cycles:u', exclude_guest is 0.
    >>>
    >>> But it doesn't make sense that we request for user-space counting
    >>> but we also get the guest report.
    >>>
    >
    > Please hold the horse and allow this possibility.
    >
    > Some authorized perf users on the host may
    > only want to count (KVM) guest user space events.
    >
    > Thanks,
    > Like Xu
    >

    Without this patch, if we don't set the ":u" modifier, exclude_guest = 1.

    perf record -e cycles ./div
    perf evlist -v
    cycles: size: 120, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|PERIOD,
    read_format: ID, disabled: 1, inherit: 1, mmap: 1, comm: 1, freq: 1, enable_on_exec: 1, task: 1,
    sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1

    So this patch doesn't change perf's original behavior.

    Thanks
    Jin Yao

    >>> To keep perf semantics consistent and clear, this patch sets
    >>> exclude_guest for user-space counting.
    >>
    >> Applied, and also added this, that you should consider doing in the
    >> future (modulo the "Committer testing:" header :) ):
    >>
    >> Committer testing:
    >>
    >> Before:
    >>
    >>    # perf record -e cycles:u
    >>    ^C[ perf record: Woken up 1 times to write data ]
    >>    [ perf record: Captured and wrote 1.231 MB perf.data (91 samples) ]
    >>    #
    >>    # perf evlist -v
    >>    cycles:u: size: 120, { sample_period, sample_freq }: 4000, sample_type:
    >> IP|TID|TIME|ID|CPU|PERIOD, read_format: ID, disabled: 1, inherit: 1, exclude_kernel: 1,
    >> exclude_hv: 1, freq: 1, sample_id_all: 1
    >>    <SNIP>
    >>    #
    >>
    >> After:
    >>
    >>    # perf record -e cycles:u
    >>    ^C[ perf record: Woken up 1 times to write data ]
    >>    [ perf record: Captured and wrote 1.263 MB perf.data (403 samples) ]
    >>    #
    >>    # perf evlist -v
    >>    cycles:u: size: 120, { sample_period, sample_freq }: 4000, sample_type:
    >> IP|TID|TIME|ID|CPU|PERIOD, read_format: ID, disabled: 1, inherit: 1, exclude_kernel: 1,
    >> exclude_hv: 1, freq: 1, sample_id_all: 1, exclude_guest: 1
    >>    #
    >>
    >> ----
    >>
    >> I.e. show actual command output before and after that demonstrates the
    >> problem and then the solution.
    >>
    >>> Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
    >>> ---
    >>>   tools/perf/util/parse-events.c | 2 ++
    >>>   1 file changed, 2 insertions(+)
    >>>
    >>> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
    >>> index 9f7260e69113..4d809f1fe269 100644
    >>> --- a/tools/perf/util/parse-events.c
    >>> +++ b/tools/perf/util/parse-events.c
    >>> @@ -1794,6 +1794,8 @@ static int get_event_modifier(struct event_modifier *mod, char *str,
    >>>           if (*str == 'u') {
    >>>               if (!exclude)
    >>>                   exclude = eu = ek = eh = 1;
    >>> +            if (!exclude_GH)
    >>> +                eG = 1;
    >>>               eu = 0;
    >>>           } else if (*str == 'k') {
    >>>               if (!exclude)
    >>> --
    >>> 2.17.1
    >>>
    >>
    >

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