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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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