linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Andrew Morton <akpm@linux-foundation.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Jerome Glisse <jglisse@redhat.com>,
	"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 15:16:24 -0700	[thread overview]
Message-ID: <20170817151624.7145db67fd3b868eff26fd05@linux-foundation.org> (raw)
In-Reply-To: <CAPcyv4j0_y9BrV-Bn57yScVJ8Nicfz2e0sSmRNG_hNPoE_LSKg@mail.gmail.com>

On Thu, 17 Aug 2017 14:59:20 -0700 Dan Williams <dan.j.williams@intel.com> 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?

That would be typical (and nice).

I'm not sure that Red Hat's decision is a broad enough guide here. 
Someone who is using Linux to make a cash register or a thermostat
faces different tradeoffs...

      parent reply	other threads:[~2017-08-17 22:16 UTC|newest]

Thread overview: 55+ 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 16:47       ` Dan Williams
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
2017-08-17 22:16       ` Andrew Morton [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170817151624.7145db67fd3b868eff26fd05@linux-foundation.org \
    --to=akpm@linux-foundation.org \
    --cc=bsingharora@gmail.com \
    --cc=dan.j.williams@intel.com \
    --cc=dnellans@nvidia.com \
    --cc=jglisse@redhat.com \
    --cc=jhubbard@nvidia.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).