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From: "Cédric Le Goater" <clg@kaod.org>
To: Michael Ellerman <mpe@ellerman.id.au>,
	David Gibson <david@gibson.dropbear.id.au>,
	Daniel Henrique Barboza <danielhb413@gmail.com>
Cc: Laurent Vivier <lvivier@redhat.com>,
	Thomas Huth <thuth@redhat.com>,
	Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	qemu-devel@nongnu.org, groug@kaod.org, qemu-ppc@nongnu.org,
	Igor Mammedov <imammedo@redhat.com>
Subject: Re: [PATCH 1/2] spapr: number of SMP sockets must be equal to NUMA nodes
Date: Wed, 31 Mar 2021 17:22:39 +0200	[thread overview]
Message-ID: <041ea566-62cd-0017-fbaa-bb56bd97d381@kaod.org> (raw)
In-Reply-To: <87blazyl5w.fsf@mpe.ellerman.id.au>

On 3/31/21 6:58 AM, Michael Ellerman wrote:
> David Gibson <david@gibson.dropbear.id.au> writes:
>> On Mon, Mar 29, 2021 at 03:32:37PM -0300, Daniel Henrique Barboza wrote:
> ...
>>
>>> We assign ibm,chip-id=0x0 to CPUs 0-3, but CPUs 2-3 are located in a
>>> different NUMA node than 0-1. This would mean that the same socket
>>> would belong to different NUMA nodes at the same time.
>>
>> Right... and I'm still not seeing why that's a problem.  AFAICT that's
>> a possible, if unexpected, situation under real hardware - though
>> maybe not for POWER9 specifically.
> 
> I think I agree.
> 
>>> I believe this is what Cedric wants to be addressed. Given that the
>>> property is called after the OPAL property ibm,chip-id, the kernel
>>> expects that the property will have the same semantics as in OPAL.
>>
>> Even on powernv, I'm not clear why chip-id is tied into the NUMA
>> configuration, rather than getting all the NUMA info from
>> associativity properties.
> 
> AFAIK we don't use chip-id for anything related to NUMA, if we do I'd
> consider that a bug.

Since PAPR only has NUMA nodes, is the use of chip-id in XIVE PAPR 
considered as a bug ? I would say so.

> We do use it for topology_physical_package_id(), but that's almost
> completely unused.

In that case, I think it should be fine to return -1 like under PowerVM.

Thanks,

C. 




  reply	other threads:[~2021-03-31 15:23 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-19 18:34 [PATCH 0/2] pseries: SMP sockets must match NUMA nodes Daniel Henrique Barboza
2021-03-19 18:34 ` [PATCH 1/2] spapr: number of SMP sockets must be equal to " Daniel Henrique Barboza
2021-03-23  1:03   ` David Gibson
2021-03-23 17:21     ` Daniel Henrique Barboza
2021-03-25  2:10       ` David Gibson
2021-03-25  8:56         ` Cédric Le Goater
2021-03-25 10:15           ` Daniel Henrique Barboza
2021-03-29  4:20           ` David Gibson
2021-03-29 15:32             ` Cédric Le Goater
2021-03-29 18:32               ` Daniel Henrique Barboza
2021-03-29 23:55                 ` Igor Mammedov
2021-03-31  0:57                 ` David Gibson
2021-03-31  4:58                   ` Michael Ellerman
2021-03-31 15:22                     ` Cédric Le Goater [this message]
2021-04-01  2:53                       ` David Gibson
2021-03-31 15:18                   ` Cédric Le Goater
2021-03-31 17:29                     ` Daniel Henrique Barboza
2021-03-31 17:40                       ` Cédric Le Goater
2021-04-01  2:59                     ` David Gibson
2021-04-01  9:21                       ` Cédric Le Goater
2021-03-29 23:51     ` Igor Mammedov
2021-03-30 21:33       ` Daniel Henrique Barboza
2021-03-19 18:34 ` [PATCH 2/2] spapr.c: remove 'ibm,chip-id' from DT Daniel Henrique Barboza

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