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From: Zi Yan <ziy@nvidia.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Shakeel Butt <shakeelb@google.com>,
	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: Wed, 1 Jul 2020 10:24:33 -0400	[thread overview]
Message-ID: <8927EC7B-76F2-4DFC-9AD8-EC2F15E3CEF9@nvidia.com> (raw)
In-Reply-To: <fdfeb902-e363-f8b5-4c63-df224b9817fa@intel.com>

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On 30 Jun 2020, at 15:31, Dave Hansen wrote:

>
>
>> 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.

We might need a different threshold (or GFP flag) for allocating new pages
in remote node for demotion. Otherwise, we could
see scenarios like: two nodes in a system are almost full and Node A is
trying to demote some pages to Node B, which triggers page demotion from
Node B to Node A. Then, we might be able to avoid a demotion cycle by not
allowing Node A to demote pages again but swapping pages to disk when Node B
is demoting its pages to Node A, but this still leads to a long reclaim path
compared to making Node A swapping to disk directly. In such cases, Node A
should just swap pages to disk without bothering Node B at all.

Maybe something like GFP_DEMOTION flag for allocating pages for demotion and
the flag requires more free pages available in the destination node to
avoid the situation above?


—
Best Regards,
Yan Zi

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  reply	other threads:[~2020-07-01 14:24 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-29 23:45 [RFC][PATCH 0/8] Migrate Pages in lieu of discard Dave Hansen
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   ` Dave Hansen
2020-06-29 23:45 ` [RFC][PATCH 2/8] mm/migrate: Defer allocating new page until needed Dave Hansen
2020-06-29 23:45   ` Dave Hansen
2020-07-01  8:47   ` Greg Thelen
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
2020-06-29 23:45   ` Dave Hansen
2020-07-01  0:47   ` David Rientjes
2020-07-01  0:47     ` David Rientjes
2020-07-01  1:29     ` Yang Shi
2020-07-01  5:41       ` David Rientjes
2020-07-01  5:41         ` David Rientjes
2020-07-01  8:54         ` Huang, Ying
2020-07-01  8:54           ` Huang, Ying
2020-07-01 18:20           ` Dave Hansen
2020-07-01 19:50             ` David Rientjes
2020-07-01 19:50               ` David Rientjes
2020-07-02  1:50               ` Huang, Ying
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
2020-07-01 19:45             ` David Rientjes
2020-07-02 10:02             ` Jonathan Cameron
2020-07-01  1:40     ` Huang, Ying
2020-07-01  1:40       ` Huang, Ying
2020-07-01 16:48     ` Dave Hansen
2020-07-01 19:25       ` David Rientjes
2020-07-01 19:25         ` David Rientjes
2020-07-02  5:02         ` Huang, Ying
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   ` Dave Hansen
2020-06-29 23:45 ` [RFC][PATCH 5/8] mm/numa: automatically generate node migration order Dave Hansen
2020-06-29 23:45   ` Dave Hansen
2020-06-30  8:22   ` Huang, Ying
2020-06-30  8:22     ` Huang, Ying
2020-07-01 18:23     ` Dave Hansen
2020-07-02  1:20       ` Huang, Ying
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   ` 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   ` Dave Hansen
2020-06-29 23:45 ` [RFC][PATCH 8/8] mm/numa: new reclaim mode to enable reclaim-based migration Dave Hansen
2020-06-29 23:45   ` Dave Hansen
2020-06-30  7:23   ` Huang, Ying
2020-06-30  7:23     ` Huang, Ying
2020-06-30 17:50     ` Yang Shi
2020-07-01  0:48       ` Huang, Ying
2020-07-01  0:48         ` Huang, Ying
2020-07-01  1:12         ` Yang Shi
2020-07-01  1:28           ` Huang, Ying
2020-07-01  1:28             ` Huang, Ying
2020-07-01 16:02       ` Dave Hansen
2020-07-03  9:30   ` Huang, Ying
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 18:36   ` Shakeel Butt
2020-06-30 18:51   ` Dave Hansen
2020-06-30 19:25     ` Shakeel Butt
2020-06-30 19:25       ` Shakeel Butt
2020-06-30 19:31       ` Dave Hansen
2020-07-01 14:24         ` Zi Yan [this message]
2020-07-01 14:32           ` [RFC] [PATCH " Dave Hansen

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