From: Felix Kuehling <felix.kuehling@amd.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: David Hildenbrand <david@redhat.com>,
Alistair Popple <apopple@nvidia.com>,
Christoph Hellwig <hch@lst.de>, Alex Sierra <alex.sierra@amd.com>,
akpm@linux-foundation.org, linux-mm@kvack.org,
rcampbell@nvidia.com, linux-ext4@vger.kernel.org,
linux-xfs@vger.kernel.org, amd-gfx@lists.freedesktop.org,
dri-devel@lists.freedesktop.org, jglisse@redhat.com,
willy@infradead.org
Subject: Re: [PATCH v6 01/10] mm: add zone device coherent type memory support
Date: Fri, 18 Feb 2022 14:37:55 -0500 [thread overview]
Message-ID: <fa20d3e3-0943-f336-db01-54367f8e2c1e@amd.com> (raw)
In-Reply-To: <20220218192640.GV4160@nvidia.com>
Am 2022-02-18 um 14:26 schrieb Jason Gunthorpe:
> On Fri, Feb 18, 2022 at 02:20:45PM -0500, Felix Kuehling wrote:
>> Am 2022-02-17 um 19:19 schrieb Jason Gunthorpe:
>>> On Thu, Feb 17, 2022 at 04:12:20PM -0500, Felix Kuehling wrote:
>>>
>>>> I'm thinking of a more theoretical approach: Instead of auditing all users,
>>>> I'd ask, what are the invariants that a vm_normal_page should have. Then
>>>> check, whether our DEVICE_COHERENT pages satisfy them. But maybe the concept
>>>> of a vm_normal_page isn't defined clearly enough for that.
>>> I would say the expectation is that only 'page cache and anon' pages
>>> are returned - ie the first union in struct page
>>>
>>> This is because the first file in your list I looked at:
>>>
>>> static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
>>> unsigned long addr, unsigned long end,
>>> struct mm_walk *walk)
>>>
>>> {
>>> page = vm_normal_page(vma, addr, ptent);
>>> [..]
>>> if (pageout) {
>>> if (!isolate_lru_page(page)) {
>>>
>>> Uses the LRU field, so this is incompatible with all the other page
>>> types.
>>>
>>> One mitigation of this might be to formally make vm_normal_page() ==
>>> 'pte to page cache and anon page' and add a new function that is 'pte
>>> to any struct page'
>>>
>>> Then go through and sort callers as appropriate.
>>>
>>> The 'pte to page cache and anon page' can detect ZONE_DEVICE by
>>> calling is_zone_device_page() insted of pte_devmap() and then continue
>>> to return NULL. This same trick will fix GUP_fast.
>> Sounds good to me. What about vm_normal_page_pmd? Should we remove the
>> pmd_devmap check from that function as well. I'm not even sure what a huge
>> zone_device page would look like, but maybe that's a worthwhile future
>> optimization for our driver.
> IIRC there are other problems here as PMDs are currently wired to THPs
> and not general at all..
>
> We have huge zone_device pages, it is just any compound page of
> contiguous pfns - you should be aggregating any contiguous string of
> logical PFNs together into a folio for performance. If the folio is
> stuffed into a PMD or not is a different question..
>
>> I'd propose the function names vm_normal_page and vm_normal_or_device_page
>> for the two functions you described.
> I wouldn't say device_page, it should be any type of page - though
> device_page is the only other option ATM, AFIAK.
Ok, then how about vm_normal_lru_page and vm_normal_any_page?
Regards,
Felix
>
>> current vm_normal_page with the pte_devmap check removed. vm_normal_page
>> could be implemented as a wrapper around vm_normal_or_device_page, which
>> just adds the !is_zone_device_page() check.
> Yes
>
> Jason
next prev parent reply other threads:[~2022-02-18 19:38 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-01 15:48 [PATCH v6 00/10] Add MEMORY_DEVICE_COHERENT for coherent device memory mapping Alex Sierra
2022-02-01 15:48 ` [PATCH v6 01/10] mm: add zone device coherent type memory support Alex Sierra
2022-02-11 16:15 ` David Hildenbrand
2022-02-11 16:39 ` David Hildenbrand
2022-02-11 16:52 ` Sierra Guiza, Alejandro (Alex)
2022-02-11 17:07 ` Felix Kuehling
2022-02-15 12:16 ` David Hildenbrand
2022-02-15 14:45 ` Jason Gunthorpe
2022-02-15 18:32 ` Christoph Hellwig
2022-02-15 19:41 ` Jason Gunthorpe
2022-02-15 21:35 ` Felix Kuehling
2022-02-15 21:47 ` Jason Gunthorpe
2022-02-15 22:49 ` Felix Kuehling
2022-02-16 2:01 ` Jason Gunthorpe
2022-02-16 16:56 ` Felix Kuehling
2022-02-16 17:28 ` Jason Gunthorpe
2022-02-16 1:23 ` Alistair Popple
2022-02-16 2:03 ` Jason Gunthorpe
2022-02-16 2:36 ` Alistair Popple
2022-02-16 8:31 ` David Hildenbrand
2022-02-16 12:26 ` Jason Gunthorpe
2022-02-17 1:05 ` Alistair Popple
2022-02-17 21:12 ` Felix Kuehling
2022-02-18 0:19 ` Jason Gunthorpe
2022-02-18 19:20 ` Felix Kuehling
2022-02-18 19:26 ` Jason Gunthorpe
2022-02-18 19:37 ` Felix Kuehling [this message]
2022-02-28 20:34 ` [PATCH] mm: split vm_normal_pages for LRU and non-LRU handling Alex Sierra
2022-02-28 22:41 ` Felix Kuehling
2022-03-01 8:03 ` David Hildenbrand
2022-03-01 16:08 ` Felix Kuehling
2022-03-01 16:22 ` David Hildenbrand
2022-03-01 16:30 ` Felix Kuehling
2022-03-01 16:32 ` David Hildenbrand
2022-02-18 0:59 ` [PATCH v6 01/10] mm: add zone device coherent type memory support Alistair Popple
2022-02-11 16:45 ` Jason Gunthorpe
2022-02-11 16:49 ` David Hildenbrand
2022-02-11 16:56 ` Jason Gunthorpe
2022-02-15 12:15 ` David Hildenbrand
2022-02-15 18:52 ` Felix Kuehling
2022-02-11 17:05 ` Felix Kuehling
2022-02-14 2:04 ` Alistair Popple
2022-02-01 15:48 ` [PATCH v6 02/10] mm: add device coherent vma selection for memory migration Alex Sierra
2022-02-01 15:48 ` [PATCH v6 03/10] mm/gup: fail get_user_pages for LONGTERM dev coherent type Alex Sierra
2022-02-01 15:48 ` [PATCH v6 04/10] drm/amdkfd: add SPM support for SVM Alex Sierra
2022-02-01 15:48 ` [PATCH v6 05/10] drm/amdkfd: coherent type as sys mem on migration to ram Alex Sierra
2022-02-01 15:48 ` [PATCH v6 06/10] lib: test_hmm add ioctl to get zone device type Alex Sierra
2022-02-01 15:48 ` [PATCH v6 07/10] lib: test_hmm add module param for " Alex Sierra
2022-02-01 15:48 ` [PATCH v6 08/10] lib: add support for device coherent type in test_hmm Alex Sierra
2022-02-01 15:49 ` [PATCH v6 09/10] tools: update hmm-test to support device coherent type Alex Sierra
2022-02-01 15:49 ` [PATCH v6 10/10] tools: update test_hmm script to support SP config Alex Sierra
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=fa20d3e3-0943-f336-db01-54367f8e2c1e@amd.com \
--to=felix.kuehling@amd.com \
--cc=akpm@linux-foundation.org \
--cc=alex.sierra@amd.com \
--cc=amd-gfx@lists.freedesktop.org \
--cc=apopple@nvidia.com \
--cc=david@redhat.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=hch@lst.de \
--cc=jgg@nvidia.com \
--cc=jglisse@redhat.com \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-xfs@vger.kernel.org \
--cc=rcampbell@nvidia.com \
--cc=willy@infradead.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).