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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: Balbir Singh <bsingharora@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	"open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)"
	<linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH 2/2] powerpc/mm: Increase MAX_PHYSMEM_BITS to 128TB with SPARSEMEM_VMEMMAP config
Date: Thu, 21 Jun 2018 21:13:03 +0530	[thread overview]
Message-ID: <bed4cc14-f6da-b416-92be-2d796fa346cd@linux.ibm.com> (raw)
In-Reply-To: <CAKTCnz=qh7fLAuor9YNm5LH5ZKETTP9RjKv_SpR4c=wX37VTEA@mail.gmail.com>

On 06/21/2018 05:02 PM, Balbir Singh wrote:
> On Thu, Jun 21, 2018 at 6:31 PM, Aneesh Kumar K.V
> <aneesh.kumar@linux.ibm.com> wrote:
>>
>> We do this only with VMEMMAP config so that our page_to_[nid/section] etc are not
>> impacted.
>>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> 
> Why 128TB, given that it's sparse_vmemmap_extreme by default, why not
> 1PB directly (50 bits)?
> 

That will impact config with VMEMMAP_EXTREME disabled with no real 
immediate benefit. We could possibly make MAX_PHYSMEM_BITS a Kconfig 
variable. s390 do that. Not sure we want to do that.

-aneesh

  parent reply	other threads:[~2018-06-21 15:43 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-21  8:31 [PATCH 1/2] powerpc/mm: Check memblock_add against MAX_PHYSMEM_BITS range Aneesh Kumar K.V
2018-06-21  8:31 ` [PATCH 2/2] powerpc/mm: Increase MAX_PHYSMEM_BITS to 128TB with SPARSEMEM_VMEMMAP config Aneesh Kumar K.V
2018-06-21 11:32   ` Balbir Singh
2018-06-21 15:42     ` Aneesh Kumar K.V
2018-06-21 15:43     ` Aneesh Kumar K.V [this message]
2018-07-24 13:59 ` [1/2] powerpc/mm: Check memblock_add against MAX_PHYSMEM_BITS range Michael Ellerman

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