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From: Dave Hansen <dave.hansen@intel.com>
To: David Rientjes <rientjes@google.com>,
	Yang Shi <yang.shi@linux.alibaba.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	kbusch@kernel.org, ying.huang@intel.com,
	dan.j.williams@intel.com
Subject: Re: [RFC][PATCH 3/8] mm/vmscan: Attempt to migrate page in lieu of discard
Date: Wed, 1 Jul 2020 08:15:22 -0700
Message-ID: <f21bc5a1-b983-837f-ed3e-70b6bd6057cc@intel.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2006302208460.1685201@chino.kir.corp.google.com>

On 6/30/20 10:41 PM, David Rientjes wrote:
> Maybe the strongest advantage of the node abstraction is the ability to 
> use autonuma and migrate_pages()/move_pages() API for moving pages 
> explicitly?  Mempolicies could be used for migration to "top-tier" memory, 
> i.e. ZONE_NORMAL or ZONE_MOVABLE, instead.

I totally agree that we _could_ introduce this new memory class as a zone.

Doing it as nodes is pretty natural since the firmware today describes
both slow (versus DRAM) and fast memory as separate nodes.  It also
means that apps can get visibility into placement with existing NUMA
tooling and ABIs.  To me, those are the two strongest reasons for PMEM.

Looking to the future, I don't think the zone approach scales.  I know
folks want to build stuff within a single socket which is a mix of:

1. High-Bandwidth, on-package memory (a la MCDRAM)
2. DRAM
3. DRAM-cached PMEM (aka. "memory mode" PMEM)
4. Non-cached PMEM

Right now, #1 doesn't exist on modern platform  and #3/#4 can't be mixed
(you only get 3 _or_ 4 at once).  I'd love to provide something here
that Intel can use to build future crazy platform configurations that
don't require kernel enabling.


  parent reply index

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-29 23:45 [RFC][PATCH 0/8] Migrate Pages " Dave Hansen
2020-06-29 23:45 ` [RFC][PATCH 1/8] mm/numa: node demotion data structure and lookup Dave Hansen
2020-06-29 23:45 ` [RFC][PATCH 2/8] mm/migrate: Defer allocating new page until needed Dave Hansen
2020-07-01  8:47   ` Greg Thelen
2020-07-01 14:46     ` Dave Hansen
2020-07-01 18:32       ` Yang Shi
2020-06-29 23:45 ` [RFC][PATCH 3/8] mm/vmscan: Attempt to migrate page in lieu of discard Dave Hansen
2020-07-01  0:47   ` David Rientjes
2020-07-01  1:29     ` Yang Shi
2020-07-01  5:41       ` David Rientjes
2020-07-01  8:54         ` Huang, Ying
2020-07-01 18:20           ` Dave Hansen
2020-07-01 19:50             ` David Rientjes
2020-07-02  1:50               ` Huang, Ying
2020-07-01 15:15         ` Dave Hansen [this message]
2020-07-01 17:21         ` Yang Shi
2020-07-01 19:45           ` David Rientjes
2020-07-02 10:02             ` Jonathan Cameron
2020-07-01  1:40     ` Huang, Ying
2020-07-01 16:48     ` Dave Hansen
2020-07-01 19:25       ` David Rientjes
2020-07-02  5:02         ` Huang, Ying
2020-06-29 23:45 ` [RFC][PATCH 4/8] mm/vmscan: add page demotion counter Dave Hansen
2020-06-29 23:45 ` [RFC][PATCH 5/8] mm/numa: automatically generate node migration order Dave Hansen
2020-06-30  8:22   ` Huang, Ying
2020-07-01 18:23     ` Dave Hansen
2020-07-02  1:20       ` Huang, Ying
2020-06-29 23:45 ` [RFC][PATCH 6/8] mm/vmscan: Consider anonymous pages without swap Dave Hansen
2020-06-29 23:45 ` [RFC][PATCH 7/8] mm/vmscan: never demote for memcg reclaim Dave Hansen
2020-06-29 23:45 ` [RFC][PATCH 8/8] mm/numa: new reclaim mode to enable reclaim-based migration Dave Hansen
2020-06-30  7:23   ` Huang, Ying
2020-06-30 17:50     ` Yang Shi
2020-07-01  0:48       ` Huang, Ying
2020-07-01  1:12         ` Yang Shi
2020-07-01  1:28           ` Huang, Ying
2020-07-01 16:02       ` Dave Hansen
2020-07-03  9:30   ` Huang, Ying
2020-06-30 18:36 ` [RFC][PATCH 0/8] Migrate Pages in lieu of discard Shakeel Butt
2020-06-30 18:51   ` Dave Hansen
2020-06-30 19:25     ` Shakeel Butt
2020-06-30 19:31       ` Dave Hansen
2020-07-01 14:24         ` [RFC] [PATCH " Zi Yan
2020-07-01 14:32           ` Dave Hansen

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