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    SubjectRe: [PATCH V3 0/4] genirq/affinity: irq vector spread among online CPUs as far as possible
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    Hi Artem,

    At 03/14/2018 11:29 AM, Dou Liyang wrote:
    > Hi All,
    >
    > At 03/13/2018 05:35 PM, Rafael J. Wysocki wrote:
    >> On Tue, Mar 13, 2018 at 9:39 AM, Artem Bityutskiy
    >> <dedekind1@gmail.com> wrote:
    >>> On Tue, 2018-03-13 at 16:35 +0800, Ming Lei wrote:
    >>>> Then looks this issue need to fix by making possible CPU count
    >>>> accurate
    >>>> because there are other resources allocated according to
    >>>> num_possible_cpus(),
    >>>> such as percpu variables.
    >>>
    >>> Short term the regression should be fixed. It is already v4.16-rc6, we
    >>> have little time left.
    >>
    >> Right.
    >>
    >>> Longer term, yeah, I agree. Kernel's notion of possible CPU count
    >>> should be realistic.
    >>
    >
    > I did a patch for that, Artem, could you help me to test it.
    >

    I didn't consider the nr_cpu_ids before. please ignore the old patch and
    try the following RFC patch.

    Thanks
    dou

    --------------------------->8-------------------------------------

    diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
    index 449d86d39965..96d568408515 100644
    --- a/drivers/acpi/acpi_processor.c
    +++ b/drivers/acpi/acpi_processor.c
    @@ -671,6 +671,23 @@ static acpi_status __init
    acpi_processor_ids_walk(acpi_handle handle,

    }

    +static void __init acpi_refill_possible_map(void)
    +{
    + unsigned int cpu, nr = 0;
    +
    + if (nr_cpu_ids <= nr_unique_ids)
    + return;
    +
    + for_each_possible_cpu(cpu) {
    + if (nr >= nr_unique_ids)
    + set_cpu_possible(cpu, false);
    + nr++;
    + }
    +
    + nr_cpu_ids = nr_unique_ids;
    + pr_info("Allowing %d possible CPUs\n", nr_cpu_ids);
    +}
    +
    static void __init acpi_processor_check_duplicates(void)
    {
    /* check the correctness for all processors in ACPI namespace */
    @@ -680,6 +697,9 @@ static void __init acpi_processor_check_duplicates(void)
    NULL, NULL, NULL);
    acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID,
    acpi_processor_ids_walk,
    NULL, NULL);
    +
    + /* make possible CPU count more realistic */
    + acpi_refill_possible_map();
    }

    bool acpi_duplicate_processor_id(int proc_id)


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