From: Jerome Glisse <jglisse@redhat.com>
To: Dan Williams <dan.j.williams@intel.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 18:02:40 -0400 [thread overview]
Message-ID: <20170817220240.GE2872@redhat.com> (raw)
In-Reply-To: <CAPcyv4j0_y9BrV-Bn57yScVJ8Nicfz2e0sSmRNG_hNPoE_LSKg@mail.gmail.com>
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.
Jerome
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next prev parent reply other threads:[~2017-08-17 22:02 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 [this message]
2017-08-17 22:06 ` Dan Williams
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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