• Arnaldo Carvalho de Melo's avatar
    perf core: Separate accounting of contexts and real addresses in a stack trace · c85b0334
    Arnaldo Carvalho de Melo authored
    The perf_sample->ip_callchain->nr value includes all the entries in the
    ip_callchain->ip[] array, real addresses and PERF_CONTEXT_{KERNEL,USER,etc},
    while what the user expects is that what is in the kernel.perf_event_max_stack
    sysctl or in the upcoming per event perf_event_attr.sample_max_stack knob be
    honoured in terms of IP addresses in the stack trace.
    So allocate a bunch of extra entries for contexts, and do the accounting
    via perf_callchain_entry_ctx struct members.
    A new sysctl, kernel.perf_event_max_contexts_per_stack is also
    introduced for investigating possible bugs in the callchain
    implementation by some arch.
    Cc: Adrian Hunter <adrian.hunter@intel.com>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Alexei Starovoitov <ast@kernel.org>
    Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: He Kuang <hekuang@huawei.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Masami Hiramatsu <mhiramat@kernel.org>
    Cc: Milian Wolff <milian.wolff@kdab.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Vince Weaver <vincent.weaver@maine.edu>
    Cc: Wang Nan <wangnan0@huawei.com>
    Cc: Zefan Li <lizefan@huawei.com>
    Link: http://lkml.kernel.org/n/tip-3b4wnqk340c4sg4gwkfdi9yk@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
kernel.txt 36.5 KB