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    SubjectRe: [PATCH v1 2/3] perf record: apply affinity masks when reading mmap buffers
    Date
    Hi,
    On 12.12.2018 15:15, Jiri Olsa wrote:
    > On Wed, Dec 12, 2018 at 10:40:22AM +0300, Alexey Budankov wrote:
    >
    > SNIP
    >
    >> int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int cpu)
    >> {
    >> + int c, nr_cpus, node;
    >> /*
    >> * The last one will be done at perf_mmap__consume(), so that we
    >> * make sure we don't prevent tools from consuming every last event in
    >> @@ -344,6 +369,17 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int c
    >> map->cpu = cpu;
    >>
    >> CPU_ZERO(&map->affinity_mask);
    >> + if (mp->affinity == PERF_AFFINITY_NODE && cpu__max_node() > 1) {
    >> + nr_cpus = cpu_map__nr(mp->cpu_map);
    >> + node = cpu__get_node(map->cpu);
    >> + for (c = 0; c < nr_cpus; c++) {
    >> + if (cpu__get_node(c) == node) {
    >> + CPU_SET(c, &map->affinity_mask);
    >> + }
    >> + }
    >> + } else if (mp->affinity == PERF_AFFINITY_CPU) {
    >> + CPU_SET(map->cpu, &map->affinity_mask);
    >> + }
    >
    > won't both of this end up in same mask?

    For tested dual socket 44 core broadwell:

    node 0 node 1
    cpu mask 0-21,44-65 22-43,66-87

    For affinity=node map->affinity_mask is either [0-21,44-65] or [22-43,66-87].
    For affinity=cpu map->affinity_mask is [0] or [1] or [2] and so on.

    Without affinity option set map->affinity_mask and record->affinity_mask are [].

    Thanks,
    Alexey

    >
    > jirka
    >

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