From: Jon Masters <jcm@jonmasters.org>
To: John Hubbard <jhubbard@nvidia.com>,
Dan Williams <dan.j.williams@intel.com>,
Jerome Glisse <jglisse@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>,
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
David Nellans <dnellans@nvidia.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>
Subject: Re: [HMM 03/15] mm/unaddressable-memory: new type of ZONE_DEVICE for unaddressable memory
Date: Tue, 25 Apr 2017 03:08:43 -0400 [thread overview]
Message-ID: <b94c74b6-14a1-a537-ada2-ee98bdafb255@jonmasters.org> (raw)
In-Reply-To: <f88de491-1cd2-75e1-4304-dc11c96b5d2a@nvidia.com>
On 04/23/2017 08:39 PM, John Hubbard wrote:
> Actually, MEMORY_DEVICE_PRIVATE / _PUBLIC seems like a good choice to
> me, because the memory may not remain CPU-unaddressable in the future.
> By that, I mean that I know of at least one company (ours) that is
> working on products that will support hardware-based memory coherence
> (and access counters to go along with that). If someone were to enable
> HMM on such a system, then the device memory would be, in fact, directly
> addressable by a CPU--thus exactly contradicting the "unaddressable" name.
I'm expecting similar with CCIX-like coherently attached accelerators
running within FPGAs and as discrete devices as well. Everyone and their
dog is working on hardware based coherence as a programming convenience
and so the notion of ZONE_DEVICE as it stood is going to rapidly evolve
over the next 18 months, maybe less. Short term anyway.
Jon.
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next prev parent reply other threads:[~2017-04-25 7:08 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-22 3:30 [HMM 00/15] HMM (Heterogeneous Memory Management) v20 Jérôme Glisse
2017-04-22 3:30 ` [HMM 01/15] mm, memory_hotplug: introduce add_pages Jérôme Glisse
2017-04-22 3:30 ` [HMM 02/15] mm/put_page: move ZONE_DEVICE page reference decrement v2 Jérôme Glisse
2017-04-22 4:46 ` Dan Williams
2017-04-22 3:30 ` [HMM 03/15] mm/unaddressable-memory: new type of ZONE_DEVICE for unaddressable memory Jérôme Glisse
2017-04-22 5:30 ` Dan Williams
2017-04-22 18:11 ` Jerome Glisse
2017-04-23 13:13 ` Dan Williams
2017-04-24 0:39 ` John Hubbard
2017-04-25 7:08 ` Jon Masters [this message]
2017-04-22 3:30 ` [HMM 04/15] mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY Jérôme Glisse
2017-04-22 3:30 ` [HMM 05/15] mm/migrate: new memory migration helper for use with device memory v4 Jérôme Glisse
2017-04-22 3:30 ` [HMM 06/15] mm/migrate: migrate_vma() unmap page from vma while collecting pages Jérôme Glisse
2017-04-22 3:30 ` [HMM 07/15] mm/hmm: heterogeneous memory management (HMM for short) v2 Jérôme Glisse
2017-04-22 3:30 ` [HMM 08/15] mm/hmm/mirror: mirror process address space on device with HMM helpers v2 Jérôme Glisse
2017-04-22 3:30 ` [HMM 09/15] mm/hmm/mirror: helper to snapshot CPU page table v2 Jérôme Glisse
2017-04-22 3:30 ` [HMM 10/15] mm/hmm/mirror: device page fault handler Jérôme Glisse
2017-04-22 3:30 ` [HMM 11/15] mm/migrate: support un-addressable ZONE_DEVICE page in migration Jérôme Glisse
2017-04-22 3:30 ` [HMM 12/15] mm/migrate: allow migrate_vma() to alloc new page on empty entry v2 Jérôme Glisse
2017-04-22 3:30 ` [HMM 13/15] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE v3 Jérôme Glisse
2017-04-22 3:30 ` [HMM 14/15] mm/hmm/devmem: dummy HMM device for ZONE_DEVICE memory v3 Jérôme Glisse
2017-04-22 3:30 ` [HMM 15/15] hmm: heterogeneous memory management documentation Jérôme Glisse
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