From: Matthew Wilcox <willy@infradead.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Michal Hocko <mhocko@kernel.org>,
Yang Shi <yang.shi@linux.alibaba.com>,
Mel Gorman <mgorman@techsingularity.net>,
Rik van Riel <riel@surriel.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>,
Dave Hansen <dave.hansen@intel.com>,
Keith Busch <keith.busch@intel.com>,
Fengguang Wu <fengguang.wu@intel.com>,
"Du, Fan" <fan.du@intel.com>,
"Huang, Ying" <ying.huang@intel.com>,
Linux MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 0/10] Another Approach to Use PMEM as NUMA Node
Date: Wed, 27 Mar 2019 13:35:20 -0700 [thread overview]
Message-ID: <20190327203520.GU10344@bombadil.infradead.org> (raw)
In-Reply-To: <CAPcyv4heiUbZvP7Ewoy-Hy=-mPrdjCjEuSw+0rwdOUHdjwetxg@mail.gmail.com>
On Wed, Mar 27, 2019 at 10:34:11AM -0700, Dan Williams wrote:
> On Wed, Mar 27, 2019 at 2:01 AM Michal Hocko <mhocko@kernel.org> wrote:
> > No, Linux NUMA implementation makes all numa nodes available by default
> > and provides an API to opt-in for more fine tuning. What you are
> > suggesting goes against that semantic and I am asking why. How is pmem
> > NUMA node any different from any any other distant node in principle?
>
> Agree. It's just another NUMA node and shouldn't be special cased.
> Userspace policy can choose to avoid it, but typical node distance
> preference should otherwise let the kernel fall back to it as
> additional memory pressure relief for "near" memory.
I think this is sort of true, but sort of different. These are
essentially CPU-less nodes; there is no CPU for which they are
fast memory. Yes, they're further from some CPUs than from others.
I have never paid attention to how Linux treats CPU-less memory nodes,
but it would make sense to me if we don't default to allocating from
remote nodes. And treating pmem nodes as being remote from all CPUs
makes a certain amount of sense to me.
eg on a four CPU-socket system, consider this as being
pmem1 --- node1 --- node2 --- pmem2
| \ / |
| X |
| / \ |
pmem3 --- node3 --- node4 --- pmem4
which I could actually see someone building with normal DRAM, and we
should probably handle the same way as pmem; for a process running on
node3, allocate preferentially from node3, then pmem3, then other nodes,
then other pmems.
next prev parent reply other threads:[~2019-03-27 20:35 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-23 4:44 [RFC PATCH 0/10] Another Approach to Use PMEM as NUMA Node Yang Shi
2019-03-23 4:44 ` [PATCH 01/10] mm: control memory placement by nodemask for two tier main memory Yang Shi
2019-03-23 17:21 ` Dan Williams
2019-03-25 19:28 ` Yang Shi
2019-03-25 23:18 ` Dan Williams
2019-03-25 23:36 ` Yang Shi
2019-03-25 23:42 ` Dan Williams
2019-03-23 4:44 ` [PATCH 02/10] mm: mempolicy: introduce MPOL_HYBRID policy Yang Shi
2019-03-23 4:44 ` [PATCH 03/10] mm: mempolicy: promote page to DRAM for MPOL_HYBRID Yang Shi
2019-03-23 4:44 ` [PATCH 04/10] mm: numa: promote pages to DRAM when it is accessed twice Yang Shi
2019-03-29 0:31 ` kbuild test robot
2019-03-23 4:44 ` [PATCH 05/10] mm: page_alloc: make find_next_best_node could skip DRAM node Yang Shi
2019-03-23 4:44 ` [PATCH 06/10] mm: vmscan: demote anon DRAM pages to PMEM node Yang Shi
2019-03-23 6:03 ` Zi Yan
2019-03-25 21:49 ` Yang Shi
2019-03-24 22:20 ` Keith Busch
2019-03-25 19:49 ` Yang Shi
2019-03-27 0:35 ` Keith Busch
2019-03-27 3:41 ` Yang Shi
2019-03-27 13:08 ` Keith Busch
2019-03-27 17:00 ` Zi Yan
2019-03-27 17:05 ` Dave Hansen
2019-03-27 17:48 ` Zi Yan
2019-03-27 18:00 ` Dave Hansen
2019-03-27 20:37 ` Zi Yan
2019-03-27 20:42 ` Dave Hansen
2019-03-28 21:59 ` Yang Shi
2019-03-28 22:45 ` Keith Busch
2019-03-23 4:44 ` [PATCH 07/10] mm: vmscan: add page demotion counter Yang Shi
2019-03-23 4:44 ` [PATCH 08/10] mm: numa: add page promotion counter Yang Shi
2019-03-23 4:44 ` [PATCH 09/10] doc: add description for MPOL_HYBRID mode Yang Shi
2019-03-23 4:44 ` [PATCH 10/10] doc: elaborate the PMEM allocation rule Yang Shi
2019-03-25 16:15 ` [RFC PATCH 0/10] Another Approach to Use PMEM as NUMA Node Brice Goglin
2019-03-25 16:56 ` Dan Williams
2019-03-25 17:45 ` Brice Goglin
2019-03-25 19:29 ` Dan Williams
2019-03-25 23:09 ` Brice Goglin
2019-03-25 23:37 ` Dan Williams
2019-03-26 12:19 ` Jonathan Cameron
2019-03-25 20:04 ` Yang Shi
2019-03-26 13:58 ` Michal Hocko
2019-03-26 18:33 ` Yang Shi
2019-03-26 18:37 ` Michal Hocko
2019-03-27 2:58 ` Yang Shi
2019-03-27 9:01 ` Michal Hocko
2019-03-27 17:34 ` Dan Williams
2019-03-27 18:59 ` Yang Shi
2019-03-27 20:09 ` Michal Hocko
2019-03-28 2:09 ` Yang Shi
2019-03-28 6:58 ` Michal Hocko
2019-03-28 18:58 ` Yang Shi
2019-03-28 19:12 ` Michal Hocko
2019-03-28 19:40 ` Yang Shi
2019-03-28 20:40 ` Michal Hocko
2019-03-28 8:21 ` Dan Williams
2019-03-27 20:14 ` Dave Hansen
2019-03-27 20:35 ` Matthew Wilcox [this message]
2019-03-27 20:40 ` Dave Hansen
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