From: Helge Deller <deller@gmx.de>
To: Mel Gorman <mgorman@techsingularity.net>,
Matthew Wilcox <willy@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mikulas Patocka <mpatocka@redhat.com>,
James Bottomley <James.Bottomley@hansenpartnership.com>,
linux-parisc@vger.kernel.org, linux-mm@kvack.org,
Vlastimil Babka <vbabka@suse.cz>,
LKML <linux-kernel@vger.kernel.org>,
linux-arch@vger.kernel.org
Subject: Re: DISCONTIGMEM is deprecated
Date: Fri, 19 Apr 2019 22:08:31 +0200 [thread overview]
Message-ID: <9e7b80a9-b90e-ac04-8b30-b2f285cd4432@gmx.de> (raw)
In-Reply-To: <20190419142835.GM18914@techsingularity.net>
On 19.04.19 16:28, Mel Gorman wrote:
> On Fri, Apr 19, 2019 at 07:05:21AM -0700, Matthew Wilcox wrote:
>> On Fri, Apr 19, 2019 at 10:43:35AM +0100, Mel Gorman wrote:
>>> DISCONTIG is essentially deprecated and even parisc plans to move to
>>> SPARSEMEM so there is no need to be fancy, this patch simply disables
>>> watermark boosting by default on DISCONTIGMEM.
>>
>> I don't think parisc is the only arch which uses DISCONTIGMEM for !NUMA
>> scenarios. Grepping the arch/ directories shows:
>>
>> alpha (does support NUMA, but also non-NUMA DISCONTIGMEM)
>> arc (for supporting more than 1GB of memory)
>> ia64 (looks complicated ...)
>> m68k (for multiple chunks of memory)
>> mips (does support NUMA but also non-NUMA)
>> parisc (both NUMA and non-NUMA)
>>
>> I'm not sure that these architecture maintainers even know that DISCONTIGMEM
>> is deprecated. Adding linux-arch to the cc.
>
> Poor wording then -- yes, DISCONTIGMEM is still used but look where it's
> used. I find it impossible to believe that any new arch would support
> DISCONTIGMEM or that DISCONTIGMEM would be selected when SPARSEMEM is
> available.`It's even more insane when you consider that SPARSEMEM can be
> extended to support VMEMMAP so that it has similar overhead to FLATMEM
> when mapping pfns to struct pages and vice-versa.
FYI, on parisc we will switch from DISCONTIGMEM to SPARSEMEM with kernel 5.2.
The patch was quite simple and it's currently in the for-next tree:
https://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux.git/commit/?h=for-next&id=281b718721a5e78288271d632731cea9697749f7
Helge
next prev parent reply other threads:[~2019-04-19 20:09 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-19 9:43 [PATCH] mm: Do not boost watermarks to avoid fragmentation for the DISCONTIG memory model Mel Gorman
2019-04-19 14:05 ` DISCONTIGMEM is deprecated Matthew Wilcox
2019-04-19 14:28 ` Mel Gorman
2019-04-19 20:08 ` Helge Deller [this message]
2019-05-05 8:53 ` Mike Rapoport
2019-04-21 6:38 ` Mike Rapoport
2019-04-21 13:26 ` Matthew Wilcox
2019-04-21 21:16 ` Mel Gorman
2019-04-23 7:13 ` Christoph Hellwig
2019-04-24 11:33 ` Mike Rapoport
2019-04-24 12:21 ` Mel Gorman
2019-04-28 8:11 ` Christoph Hellwig
2019-05-01 20:46 ` Mike Rapoport
2019-04-22 17:29 ` Christopher Lameter
2019-04-23 16:49 ` Meelis Roos
2019-04-28 8:13 ` Christoph Hellwig
2019-04-29 16:58 ` Luck, Tony
2019-04-29 20:09 ` Christoph Hellwig
2019-04-30 13:40 ` Christopher Lameter
2019-04-23 6:33 ` [PATCH] mm: Do not boost watermarks to avoid fragmentation for the DISCONTIG memory model Vlastimil Babka
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