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Re: [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25

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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.

Cheers,
Jérôme

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[HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25 Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:10 +0200
  [HMM-v25 03/19] mm/hmm/mirror: mirror process address space on device with HMM helpers v3 Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:10 +0200
  [HMM-v25 14/19] mm/migrate: new memory migration helper for use with device memory v5 Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:10 +0200
  [HMM-v25 08/19] mm/ZONE_DEVICE: special case put_page() for device private pages v4 Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:10 +0200
  [HMM-v25 19/19] mm/hmm: add new helper to hotplug CDM memory region v3 Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:10 +0200
  [HMM-v25 02/19] mm/hmm: heterogeneous memory management (HMM for short) v5 Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:10 +0200
  [HMM-v25 17/19] mm/migrate: allow migrate_vma() to alloc new page on empty entry v4 Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:10 +0200
  [HMM-v25 11/19] mm/hmm/devmem: device memory hotplug using ZONE_DEVICE v7 Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:10 +0200
  [HMM-v25 10/19] mm/memcontrol: support MEMORY_DEVICE_PRIVATE v4 Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:10 +0200
  [HMM-v25 18/19] mm/device-public-memory: device memory cache coherent with CPU v5 Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:10 +0200
  [HMM-v25 01/19] hmm: heterogeneous memory management documentation v3 Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:20 +0200
  [HMM-v25 04/19] mm/hmm/mirror: helper to snapshot CPU page table v4 Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:20 +0200
  [HMM-v25 05/19] mm/hmm/mirror: device page fault handler Jérôme Glisse <jglisse@redhat.com> - 2017-08-17 02:20 +0200
  Re: [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25 Andrew Morton <akpm@linux-foundation.org> - 2017-08-17 23:40 +0200
    Re: [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25 Dan Williams <dan.j.williams@intel.com> - 2017-08-18 00:00 +0200
      Re: [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25 Dan Williams <dan.j.williams@intel.com> - 2017-08-18 00:10 +0200
      Re: [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25 Jerome Glisse <jglisse@redhat.com> - 2017-08-18 00:10 +0200
      Re: [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25 Andrew Morton <akpm@linux-foundation.org> - 2017-08-18 00:20 +0200
    Re: [HMM-v25 00/19] HMM (Heterogeneous Memory Management) v25 Jerome Glisse <jglisse@redhat.com> - 2017-08-18 00:00 +0200

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