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From: Dave Hansen <dave.hansen@intel.com>
To: Shakeel Butt <shakeelb@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux MM <linux-mm@kvack.org>,
	Yang Shi <yang.shi@linux.alibaba.com>,
	David Rientjes <rientjes@google.com>,
	Huang Ying <ying.huang@intel.com>,
	Dan Williams <dan.j.williams@intel.com>
Subject: Re: [RFC][PATCH 0/8] Migrate Pages in lieu of discard
Date: Tue, 30 Jun 2020 12:31:05 -0700
Message-ID: <fdfeb902-e363-f8b5-4c63-df224b9817fa@intel.com> (raw)
In-Reply-To: <CALvZod5-YuMC8b6rs=a_ahh0WF14wgKJBW18CARJtGa_bYUn0Q@mail.gmail.com>

On 6/30/20 12:25 PM, Shakeel Butt wrote:
>> Since there is never a demotion path out of the set of
>> all nodes, the common case would be that there is no demotion path out
>> of a reclaim node set.
>>
>> If that's true, I'd say that the kernel still needs to consider
>> migrations even within the set.
> In my opinion it should be a user defined policy but I think that
> discussion is orthogonal to this patch series. As I understand, this
> patch series aims to add the migration-within-reclaim infrastructure,
> IMO the policies, optimizations, heuristics can come later.

Yes, this should be considered to add the infrastructure and one
_simple_ policy implementation which sets up migration away from nodes
with CPUs to more distant nodes without CPUs.

This simple policy will be useful for (but not limited to) volatile-use
persistent memory like Intel's Optane DIMMS.

> BTW is this proposal only for systems having multi-tiers of memory?
> Can a multi-node DRAM-only system take advantage of this proposal? For
> example I have a system with two DRAM nodes running two jobs
> hardwalled to each node. For each job the other node is kind of
> low-tier memory. If I can describe the per-job demotion paths then
> these jobs can take advantage of this proposal during occasional
> peaks.

I don't see any reason it could not work there.  There would just need
to be a way to set up a different demotion path policy that what was
done here.


  reply index

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-29 23:45 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
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 [this message]
2020-07-01 14:24         ` [RFC] [PATCH " Zi Yan
2020-07-01 14:32           ` Dave Hansen

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