lkml.org 
[lkml]   [2018]   [Apr]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 1/5] perf pmu: Fix core PMU alias list for X86 platform
    Date
    From: Kan Liang <kan.liang@linux.intel.com>

    When counting uncore event with alias, core event is mistakenly
    involved, for example:

    perf stat --no-merge -e "unc_m_cas_count.all" -C0 sleep 1

    Performance counter stats for 'CPU(s) 0':

    0 unc_m_cas_count.all [uncore_imc_4]
    0 unc_m_cas_count.all [uncore_imc_2]
    0 unc_m_cas_count.all [uncore_imc_0]
    153,640 unc_m_cas_count.all [cpu]
    0 unc_m_cas_count.all [uncore_imc_5]
    25,026 unc_m_cas_count.all [uncore_imc_3]
    0 unc_m_cas_count.all [uncore_imc_1]

    1.001447890 seconds time elapsed

    The reason is that current implementation doesn't check PMU name of a
    event when adding its alias into the alias list for core PMU. The
    uncore event aliases are mistakenly added.

    This bug was introduced in:
    commit 14b22ae028de ("perf pmu: Add helper function is_pmu_core to
    detect PMU CORE devices")

    Checking the PMU name for all PMUs on X86 and other architectures except
    ARM.
    There is no behavior change for ARM.

    Fixes: 14b22ae028de ("perf pmu: Add helper function is_pmu_core to detect PMU CORE devices")
    Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
    ---
    tools/perf/util/pmu.c | 20 +++++++-------------
    1 file changed, 7 insertions(+), 13 deletions(-)

    diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
    index 064bdcb..0df2a02 100644
    --- a/tools/perf/util/pmu.c
    +++ b/tools/perf/util/pmu.c
    @@ -539,9 +539,10 @@ static bool pmu_is_uncore(const char *name)

    /*
    * PMU CORE devices have different name other than cpu in sysfs on some
    - * platforms. looking for possible sysfs files to identify as core device.
    + * platforms.
    + * Looking for possible sysfs files to identify the arm core device.
    */
    -static int is_pmu_core(const char *name)
    +static int is_arm_pmu_core(const char *name)
    {
    struct stat st;
    char path[PATH_MAX];
    @@ -550,12 +551,6 @@ static int is_pmu_core(const char *name)
    if (!sysfs)
    return 0;

    - /* Look for cpu sysfs (x86 and others) */
    - scnprintf(path, PATH_MAX, "%s/bus/event_source/devices/cpu", sysfs);
    - if ((stat(path, &st) == 0) &&
    - (strncmp(name, "cpu", strlen("cpu")) == 0))
    - return 1;
    -
    /* Look for cpu sysfs (specific to arm) */
    scnprintf(path, PATH_MAX, "%s/bus/event_source/devices/%s/cpus",
    sysfs, name);
    @@ -662,6 +657,7 @@ static void pmu_add_cpu_aliases(struct list_head *head, struct perf_pmu *pmu)
    struct pmu_events_map *map;
    struct pmu_event *pe;
    const char *name = pmu->name;
    + const char *pname;

    map = perf_pmu__find_map(pmu);
    if (!map)
    @@ -680,11 +676,9 @@ static void pmu_add_cpu_aliases(struct list_head *head, struct perf_pmu *pmu)
    break;
    }

    - if (!is_pmu_core(name)) {
    - /* check for uncore devices */
    - if (pe->pmu == NULL)
    - continue;
    - if (strncmp(pe->pmu, name, strlen(pe->pmu)))
    + if (!is_arm_pmu_core(name)) {
    + pname = pe->pmu ? pe->pmu : "cpu";
    + if (strncmp(pname, name, strlen(pname)))
    continue;
    }

    --
    2.7.4
    \
     
     \ /
      Last update: 2018-04-24 20:21    [W:2.507 / U:0.164 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site