Hi Andrew,
在 2020/6/25 3:26, Andrew Morton 写道:
> On Tue, 23 Jun 2020 15:23:29 -0400 Nitesh Narayan Lal <nitesh@xxxxxxxxxx> wrote:
>
>> From: Alex Belits <abelits@xxxxxxxxxxx>
>>
>> The current implementation of cpumask_local_spread() does not respect the
>> isolated CPUs, i.e., even if a CPU has been isolated for Real-Time task,
>> it will return it to the caller for pinning of its IRQ threads. Having
>> these unwanted IRQ threads on an isolated CPU adds up to a latency
>> overhead.
>>
>> Restrict the CPUs that are returned for spreading IRQs only to the
>> available housekeeping CPUs.
>>
>> ...
>>
>> --- a/lib/cpumask.c
>> +++ b/lib/cpumask.c
>> @@ -6,6 +6,7 @@
>> #include <linux/export.h>
>> #include <linux/memblock.h>
>> #include <linux/numa.h>
>> +#include <linux/sched/isolation.h>
>>
>> /**
>> * cpumask_next - get the next cpu in a cpumask
>> @@ -205,22 +206,27 @@ void __init free_bootmem_cpumask_var(cpumask_var_t mask)
>> */
>> unsigned int cpumask_local_spread(unsigned int i, int node)
>> {
>> - int cpu;
>> + int cpu, hk_flags;
>> + const struct cpumask *mask;
>>
>> + hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ;
>> + mask = housekeeping_cpumask(hk_flags);
>> /* Wrap: we always want a cpu. */
>> - i %= num_online_cpus();
>> + i %= cpumask_weight(mask);
>>
>> if (node == NUMA_NO_NODE) {
>> - for_each_cpu(cpu, cpu_online_mask)
>> + for_each_cpu(cpu, mask) {
>> if (i-- == 0)
>> return cpu;
>> + }
>> } else {
>> /* NUMA first. */
>> - for_each_cpu_and(cpu, cpumask_of_node(node), cpu_online_mask)
>> + for_each_cpu_and(cpu, cpumask_of_node(node), mask) {
>> if (i-- == 0)
>> return cpu;
>> + }
>>
>> - for_each_cpu(cpu, cpu_online_mask) {
>> + for_each_cpu(cpu, mask) {
>> /* Skip NUMA nodes, done above. */
>> if (cpumask_test_cpu(cpu, cpumask_of_node(node)))
>> continue;
>
> Are you aware of these changes to cpu_local_spread()?
> https://lore.kernel.org/lkml/1582768688-2314-1-git-send-email-zhangshaokun@xxxxxxxxxxxxx/
>
> I don't see a lot of overlap but it would be nice for you folks to
Yeah, it's a different issue from Nitesh. About our's patch, it has been
linux-next long time, will it be merged in Linus's tree?
Thanks,
Shaokun
> check each other's homework ;)
>
>
>
> .
>
