Re: [RESEND RFC PATCH 1/2] x86/cpu hotplug: make apicid <--> cpuid mapping persistent
From: Hanjun Guo
Date: Sat Apr 25 2015 - 06:15:25 EST
On 2015/4/24 22:45, Rafael J. Wysocki wrote:
> On Friday, April 24, 2015 05:58:32 PM Gu Zheng wrote:
>> Yasuaki Ishimatsu found that with node online/offline, cpu<->node relationship
>> is established. Because workqueue uses a info which was established at boot
>> time, but it may be changed by node hotpluging.
>> Once pool->node points to a stale node, following allocation failure
>> SLUB: Unable to allocate memory on node 2 (gfp=0x80d0)
>> cache: kmalloc-192, object size: 192, buffer size: 192, default
>> 1, min order: 0
>> node 0: slabs: 6172, objs: 259224, free: 245741
>> node 1: slabs: 3261, objs: 136962, free: 127656
>> As the apicid <---> pxm and pxm <--> node relationship are persistent, then
>> the apicid <--> node mapping is persistent, so the root cause is the
>> cpu-id <-> lapicid mapping is not persistent (because the currently implementation
>> always choose the first free cpu id for the new added cpu). If we can build
>> persistent cpu-id <-> lapicid relationship, this problem will be fixed.
>> This patch tries to build the whole world mapping cpuid <-> apicid <-> pxm <-> node
>> for all possible processor at the boot, the detail implementation are 2 steps:
>> Step1: generate a logic cpu id for all the local apic (both enabled and dsiabled)
>> when register local apic
>> Step2: map the cpu to the phyical node via an additional acpi ns walk for processor.
>> Please refer to:
>> for the previous discussion.
>> Reported-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
>> Signed-off-by: Gu Zheng <guz.fnst@xxxxxxxxxxxxxx>
> This one will conflict with the ARM64 ACPI material when that goes in, so it'll
> need to be rebased on top of that.
Yes, please. Then I will take a look too.
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