From: Dave Hansen <dave.hansen@intel.com>
To: Andi Kleen <ak@linux.intel.com>, Ben Widawsky <ben.widawsky@intel.com>
Cc: linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
Dan Williams <dan.j.williams@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
David Hildenbrand <david@redhat.com>,
David Rientjes <rientjes@google.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
Johannes Weiner <hannes@cmpxchg.org>,
Jonathan Corbet <corbet@lwn.net>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Lee Schermerhorn <lee.schermerhorn@hp.com>,
Li Xinhai <lixinhai.lxh@gmail.com>,
Mel Gorman <mgorman@techsingularity.net>,
Michal Hocko <mhocko@kernel.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Mina Almasry <almasrymina@google.com>, Tejun Heo <tj@kernel.org>,
Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH 00/18] multiple preferred nodes
Date: Mon, 22 Jun 2020 14:07:49 -0700 [thread overview]
Message-ID: <882873cd-f1a7-090e-49a1-516bea529f76@intel.com> (raw)
In-Reply-To: <20200622205430.GA818054@tassilo.jf.intel.com>
On 6/22/20 1:54 PM, Andi Kleen wrote:
> On Fri, Jun 19, 2020 at 09:24:07AM -0700, Ben Widawsky wrote:
>> This patch series introduces the concept of the MPOL_PREFERRED_MANY mempolicy.
> So the reason for having a new policy is that you're worried some legacy
> application passes multiple nodes to MPOL_PREFERRED, where all but the
> first would be currently ignored. Is that right?
It's one thing if our internal implementation threw away all but the
first preferred node silently. We do that, but we also go pretty far to
blab in the manpage to solidify this behavior:
If nodemask specifies more than one node ID, the first node
in the mask will be selected as the preferred node.
I think it's dangerous to go and actively break that promise. It means
that newer apps will silently not get the behavior they ask for if they
run on an old kernel.
We also promise:
The kernel will try to allocate pages from this node first and
fall back to "near by" nodes if the preferred node is low on
free memory.
A user could legitimately say that the kernel breaks this promise if
they passed multiple preferred nodes, one of them had lots of free
memory, and that node node was not preferred.
next prev parent reply other threads:[~2020-06-22 21:07 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-19 16:24 Ben Widawsky
2020-06-19 16:24 ` [PATCH 01/18] mm/mempolicy: Add comment for missing LOCAL Ben Widawsky
2020-06-24 7:55 ` Michal Hocko
2020-06-19 16:24 ` [PATCH 02/18] mm/mempolicy: Use node_mem_id() instead of node_id() Ben Widawsky
2020-06-24 8:25 ` Michal Hocko
2020-06-24 16:48 ` Ben Widawsky
2020-06-26 12:30 ` Michal Hocko
2020-06-19 16:24 ` [PATCH 03/18] mm/page_alloc: start plumbing multi preferred node Ben Widawsky
2020-06-19 16:24 ` [PATCH 04/18] mm/page_alloc: add preferred pass to page allocation Ben Widawsky
2020-06-19 16:24 ` [PATCH 05/18] mm/mempolicy: convert single preferred_node to full nodemask Ben Widawsky
2020-06-19 16:24 ` [PATCH 06/18] mm/mempolicy: Add MPOL_PREFERRED_MANY for multiple preferred nodes Ben Widawsky
2020-06-19 16:24 ` [PATCH 07/18] mm/mempolicy: allow preferred code to take a nodemask Ben Widawsky
2020-06-19 16:24 ` [PATCH 08/18] mm/mempolicy: refactor rebind code for PREFERRED_MANY Ben Widawsky
2020-06-19 16:24 ` [PATCH 09/18] mm: Finish handling MPOL_PREFERRED_MANY Ben Widawsky
2020-06-19 16:24 ` [PATCH 10/18] mm: clean up alloc_pages_vma (thp) Ben Widawsky
2020-06-19 16:24 ` [PATCH 11/18] mm: Extract THP hugepage allocation Ben Widawsky
2020-06-19 16:24 ` [PATCH 12/18] mm/mempolicy: Use __alloc_page_node for interleaved Ben Widawsky
2020-06-19 16:24 ` [PATCH 13/18] mm: kill __alloc_pages Ben Widawsky
2020-06-19 16:24 ` [PATCH 14/18] mm/mempolicy: Introduce policy_preferred_nodes() Ben Widawsky
2020-06-19 16:24 ` [PATCH 15/18] mm: convert callers of __alloc_pages_nodemask to pmask Ben Widawsky
2020-06-19 16:24 ` [PATCH 16/18] alloc_pages_nodemask: turn preferred nid into a nodemask Ben Widawsky
2020-06-19 16:24 ` [PATCH 17/18] mm: Use less stack for page allocations Ben Widawsky
2020-06-19 16:24 ` [PATCH 18/18] mm/mempolicy: Advertise new MPOL_PREFERRED_MANY Ben Widawsky
2020-06-22 7:09 ` [PATCH 00/18] multiple preferred nodes Michal Hocko
2020-06-23 11:20 ` Michal Hocko
2020-06-23 16:12 ` Ben Widawsky
2020-06-24 7:52 ` Michal Hocko
2020-06-24 16:16 ` Ben Widawsky
2020-06-24 18:39 ` Michal Hocko
2020-06-24 19:37 ` Ben Widawsky
2020-06-24 19:51 ` Michal Hocko
2020-06-24 20:01 ` Ben Widawsky
2020-06-24 20:07 ` Michal Hocko
2020-06-24 20:23 ` Ben Widawsky
2020-06-24 20:42 ` Michal Hocko
2020-06-24 20:55 ` Ben Widawsky
2020-06-25 6:28 ` Michal Hocko
2020-06-26 21:39 ` Ben Widawsky
2020-06-29 10:16 ` Michal Hocko
2020-06-22 20:54 ` Andi Kleen
2020-06-22 21:02 ` Ben Widawsky
2020-06-22 21:07 ` Dave Hansen [this message]
2020-06-22 22:02 ` Andi Kleen
-- strict thread matches above, loose matches on Subject: below --
2020-06-19 16:23 Ben Widawsky
2020-06-19 16:25 ` Ben Widawsky
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