linux-kernel - Re: [RESEND RFC PATCH 1/2] x86/cpu hotplug: make apicid <--> cpuid mapping persistent

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Date:	Mon, 27 Apr 2015 18:28:12 +0800
From:	Gu Zheng <guz.fnst@...fujitsu.com>
To:	Hanjun Guo <guohanjun@...wei.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>
CC:	<linux-kernel@...r.kernel.org>, <tj@...nel.org>,
	<mingo@...hat.com>, <x86@...nel.org>, <akpm@...ux-foundation.org>,
	<hpa@...or.com>, <linux-acpi@...r.kernel.org>,
	<laijs@...fujitsu.com>, <isimatu.yasuaki@...fujitsu.com>,
	<kamezawa.hiroyu@...fujitsu.com>, <tangchen@...fujitsu.com>,
	<izumi.taku@...fujitsu.com>
Subject: Re: [RESEND RFC PATCH 1/2] x86/cpu hotplug: make apicid <--> cpuid
 mapping persistent

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
>>> happens.
>>>   ==
>>>      SLUB: Unable to allocate memory on node 2 (gfp=0x80d0)
>>>       cache: kmalloc-192, object size: 192, buffer size: 192, default
>>> order:
>>>     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:
>>> https://lkml.org/lkml/2015/2/27/145
>>> https://lkml.org/lkml/2015/3/25/989
>>> for the previous discussion.
>>>
>>> Reported-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
>>> Signed-off-by: Gu Zheng <guz.fnst@...fujitsu.com>
>> 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.

Regards,
Gu

> 
> Thanks
> Hanjun
> 
> .
> 


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