From: Michael Ellerman <mpe@ellerman•id.au>
To: Anshuman Khandual <khandual@linux•vnet.ibm.com>
Cc: linuxppc-dev@ozlabs•org, mikey@neuling•org, nacc@linux•vnet.ibm.com
Subject: Re: [RFC] powerpc/numa: Use VPHN based node ID information on shared processor LPARs
Date: Wed, 14 Oct 2015 20:19:20 +1100 [thread overview]
Message-ID: <1444814360.1843.1.camel@ellerman.id.au> (raw)
In-Reply-To: <1444813335-4009-1-git-send-email-khandual@linux.vnet.ibm.com>
On Wed, 2015-10-14 at 14:32 +0530, Anshuman Khandual wrote:
> On shared processor LPARs, H_HOME_NODE_ASSOCIATIVITY hcall provides the
> dynamic virtual-physical mapping for any given processor. Currently we
> use VPHN node ID information only after getting either a PRRN or a VPHN
> event. But during boot time inside the function numa_setup_cpu, we still
> query the OF device tree for the node ID value which might be different
> than what can be fetched from the H_HOME_NODE_ASSOCIATIVITY hcall. In a
> scenario where there are no PRRN or VPHN event after boot, all node-cpu
> mapping will remain incorrect there after.
>
> With this proposed change, numa_setup_cpu will try to override the OF
> device tree fetched node ID information with H_HOME_NODE_ASSOCIATIVITY
> hcall fetched node ID value. Right now shared processor property of the
> LPAR cannot be queried as VPA inializaion happens after numa_setup_cpu
> during boot time. So initmem_init function has been moved after ppc_md.
> setup_arch inside setup_arch during boot.
I would be *very* reluctant to change the order of initmem_init() vs
setup_arch().
At a minimum you'd need to go through every setup_arch() implementation and
carefully determine if the ordering of what it does matters vs initmem_init().
And then you'd need to test on every affected platform.
So I suggest you think of a different way to do it if at all possible.
cheers
next prev parent reply other threads:[~2015-10-14 9:19 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-14 9:02 [RFC] powerpc/numa: Use VPHN based node ID information on shared processor LPARs Anshuman Khandual
2015-10-14 9:19 ` Michael Ellerman [this message]
2015-10-14 10:13 ` Anshuman Khandual
2015-10-16 2:24 ` Michael Ellerman
2015-10-16 5:55 ` Anshuman Khandual
2015-10-16 2:27 ` Michael Ellerman
2015-10-16 5:55 ` Anshuman Khandual
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