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List: linux-ia64
Subject: Re: Allow to change SD_NODES_PER_DOMAIN at configuration or boot
From: Xavier Bru <xavier.bru () bull ! net>
Date: 2005-02-17 11:05:00
Message-ID: 42147A5C.30007 () bull ! net
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Nick Piggin wrote:
>Right. It may make more sense to have the setup based on some
>maximum distance between nodes. Eg. all nodes less than distance
>10 away from node0 are to be in node0's first level NUMA domain
>(the next level is always global, IIRC).
>
>Then you would still need some configuration option, but it would
>appear to be a more useful metric to use.
>
>
>
Hello Nick & all,
Do you mean that there should ever be only one NUMA sched-domain level ?
On a 2x4x4 cpus machine, we could in theory have SD_NODES_PER_DOMAIN=4,
thus providing a 2 level NUMA sched-domain (domain 0 spans 4 cpus,
domain 1 spans 16, domain 2 is global and spans 32).
But it is true that this configuration does not show evident performance
gains upon SD_NODES_PER_DOMAIN=8 (domain 0 spans 4 cpus, domain 1 is
global and spans 32), at least on parallel compilation of the kernel.
Providing SD_NODES_PER_DOMAIN as a boot parameter was also intended to
choose between a multilevel sched-domains or not.
--
Sincères salutations.
["xavier.bru.vcf" (xavier.bru.vcf)]
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