Re: [RESEND RFC PATCH 1/2] x86/cpu hotplug: make apicid <--> cpuid mapping persistent
From: Gu Zheng
Date: Mon Apr 27 2015 - 07:03:08 EST
Hi Hanjun, Rafael,
On 04/25/2015 06:14 PM, Hanjun Guo wrote:
> 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.
Thanks for your reminder, will rebase it soon.
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