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    SubjectRe: [PATCH 38/40] perf session: Handle index files generally
    On 5/17/15 6:30 PM, Namhyung Kim wrote:
    > The current code assumes that the number of index item and cpu are
    > matched so it creates that number of threads. But it's not the case
    > of non-system-wide session or data came from different machine.
    >
    > Just creates threads at most number of online cpus and process data.

    -----8<-----

    > @@ -1717,6 +1742,7 @@ int perf_session__process_events_mt(struct perf_session *session, void *arg)
    > int err, i, k;
    > int nr_index = session->header.nr_index;
    > u64 size = perf_data_file__size(file);
    > + int nr_thread = sysconf(_SC_NPROCESSORS_ONLN);

    It's not clear to me how this multi-threaded perf is going to work on
    large systems especially this patch if a system has holes in the active
    cpus. e.g,

    # lscpu
    Architecture: sparc64
    CPU op-mode(s): 32-bit, 64-bit
    Byte Order: Big Endian
    CPU(s): 704
    On-line CPU(s) list:
    32-63,128-223,256-351,384-479,576-831,864-927,960-1023
    Thread(s) per core: 12
    Core(s) per socket: 18
    Socket(s): 3
    NUMA node(s): 4
    NUMA node0 CPU(s): 32-63,128-223
    NUMA node1 CPU(s): 256-351,384-479
    NUMA node2 CPU(s): 576-767
    NUMA node3 CPU(s): 768-831,864-927,960-1023

    So you are going to spawn 704 threads? Each thread handles a per-cpu buffer?

    yes, I still need to find time to take if for a test drive; maybe by the
    end of the week.

    David

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