From: Dan Williams <dan.j.williams@intel.com>
To: 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>, John Hubbard <jhubbard@nvidia.com>,
David Nellans <dnellans@nvidia.com>,
Balbir Singh <bsingharora@gmail.com>
Subject: Re: [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25
Date: Thu, 17 Aug 2017 15:06:07 -0700 [thread overview]
Message-ID: <CAPcyv4h6CEVe1xj6xAX6RaP__Z_YT4RMRwTJg3oaQgiDh1i0UA@mail.gmail.com> (raw)
In-Reply-To: <20170817220240.GE2872@redhat.com>
On Thu, Aug 17, 2017 at 3:02 PM, Jerome Glisse <jglisse@redhat.com> wrote:
> On Thu, Aug 17, 2017 at 02:59:20PM -0700, Dan Williams wrote:
>> On Thu, Aug 17, 2017 at 2:55 PM, Jerome Glisse <jglisse@redhat.com> wrote:
>> > On Thu, Aug 17, 2017 at 02:39:16PM -0700, Andrew Morton wrote:
>> >> On Wed, 16 Aug 2017 20:05:29 -0400 J__r__me Glisse <jglisse@redhat.com> wrote:
>> >>
>> >> > Heterogeneous Memory Management (HMM) (description and justification)
>> >>
>> >> The patchset adds 55 kbytes to x86_64's mm/*.o and there doesn't appear
>> >> to be any way of avoiding this overhead, or of avoiding whatever
>> >> runtime overheads are added.
>> >
>> > HMM have already been integrated in couple of Red Hat kernel and AFAIK there
>> > is no runtime performance issue reported. Thought the RHEL version does not
>> > use static key as Dan asked.
>> >
>> >>
>> >> It also adds 18k to arm's mm/*.o and arm doesn't support HMM at all.
>> >>
>> >> So that's all quite a lot of bloat for systems which get no benefit from
>> >> the patchset. What can we do to improve this situation (a lot)?
>> >
>> > I will look into why object file grow so much on arm. My guess is that the
>> > new migrate code is the bulk of that. I can hide the new page migration code
>> > behind a kernel configuration flag.
>>
>> Shouldn't we completely disable all of it unless there is a driver in
>> the kernel that selects it?
>
> At one point people asked to be able to use the new migrate helper without
> HMM and hence why it is not behind any HMM kconfig.
>
> IIRC even ARM folks were interested pretty much all SOC have several DMA
> engine that site idle and i think people where toying with the idea of using
> this new helper to make use of them. But i can add a different kconfig to
> hide this code and if people want to use it they will have to select it.
If they were interested then I would expect their use case would be
included in this patchset so the infrastructure and at least one
consumer can land together.
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next prev parent reply other threads:[~2017-08-17 22:06 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-17 0:05 [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25 Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 01/19] hmm: heterogeneous memory management documentation v3 Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 02/19] mm/hmm: heterogeneous memory management (HMM for short) v5 Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 03/19] mm/hmm/mirror: mirror process address space on device with HMM helpers v3 Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 04/19] mm/hmm/mirror: helper to snapshot CPU page table v4 Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 05/19] mm/hmm/mirror: device page fault handler Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 06/19] mm/memory_hotplug: introduce add_pages Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 07/19] mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory v5 Jérôme Glisse
2018-12-20 8:33 ` Dan Williams
2018-12-20 16:15 ` Jerome Glisse
2018-12-20 16:15 ` Jerome Glisse
2018-12-20 16:47 ` Dan Williams
2018-12-20 16:47 ` Dan Williams
2018-12-20 16:57 ` Jerome Glisse
2018-12-20 16:57 ` Jerome Glisse
2017-08-17 0:05 ` [HMM-v25 08/19] mm/ZONE_DEVICE: special case put_page() for device private pages v4 Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 09/19] mm/memcontrol: allow to uncharge page without using page->lru field Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 10/19] mm/memcontrol: support MEMORY_DEVICE_PRIVATE v4 Jérôme Glisse
2017-09-05 17:13 ` Laurent Dufour
2017-09-05 17:21 ` Jerome Glisse
2017-08-17 0:05 ` [HMM-v25 11/19] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE v7 Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 12/19] mm/hmm/devmem: dummy HMM device for ZONE_DEVICE memory v3 Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 13/19] mm/migrate: new migrate mode MIGRATE_SYNC_NO_COPY Jérôme Glisse
2017-08-17 21:12 ` Andrew Morton
2017-08-17 21:44 ` Jerome Glisse
2017-08-17 0:05 ` [HMM-v25 14/19] mm/migrate: new memory migration helper for use with device memory v5 Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 15/19] mm/migrate: migrate_vma() unmap page from vma while collecting pages Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 16/19] mm/migrate: support un-addressable ZONE_DEVICE page in migration v3 Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 17/19] mm/migrate: allow migrate_vma() to alloc new page on empty entry v4 Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 18/19] mm/device-public-memory: device memory cache coherent with CPU v5 Jérôme Glisse
2017-08-17 0:05 ` [HMM-v25 19/19] mm/hmm: add new helper to hotplug CDM memory region v3 Jérôme Glisse
2017-09-04 3:09 ` Bob Liu
2017-09-04 15:51 ` Jerome Glisse
2017-09-05 1:13 ` Bob Liu
2017-09-05 2:38 ` Jerome Glisse
2017-09-05 3:50 ` Bob Liu
2017-09-05 13:50 ` Jerome Glisse
2017-09-05 16:18 ` Dan Williams
2017-09-05 19:00 ` Ross Zwisler
2017-09-05 19:20 ` Jerome Glisse
2017-09-08 19:43 ` Ross Zwisler
2017-09-08 20:29 ` Jerome Glisse
2017-09-05 18:54 ` Ross Zwisler
2017-09-06 1:25 ` Bob Liu
2017-09-06 2:12 ` Jerome Glisse
2017-09-07 2:06 ` Bob Liu
2017-09-07 17:00 ` Jerome Glisse
2017-09-07 17:27 ` Jerome Glisse
2017-09-08 1:59 ` Bob Liu
2017-09-08 20:43 ` Dan Williams
2017-11-17 3:47 ` chetan L
2017-09-05 3:36 ` Balbir Singh
2017-08-17 21:39 ` [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25 Andrew Morton
2017-08-17 21:55 ` Jerome Glisse
2017-08-17 21:59 ` Dan Williams
2017-08-17 22:02 ` Jerome Glisse
2017-08-17 22:06 ` Dan Williams [this message]
2017-08-17 22:16 ` Andrew Morton
2017-12-13 12:10 ` Figo.zhang
2017-12-13 16:12 ` Jerome Glisse
2017-12-14 2:48 ` Figo.zhang
2017-12-14 3:16 ` Jerome Glisse
2017-12-14 3:53 ` Figo.zhang
2017-12-14 4:16 ` Jerome Glisse
2017-12-14 7:05 ` Figo.zhang
2017-12-14 15:28 ` Jerome Glisse
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