From: Matthew Wilcox <willy@infradead.org>
To: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
markhemm@googlemail.com, viro@zeniv.linux.org.uk,
david@redhat.com, khalid@kernel.org, jthoughton@google.com,
corbet@lwn.net, dave.hansen@intel.com, kirill@shutemov.name,
luto@kernel.org, brauner@kernel.org, arnd@arndb.de,
ebiederm@xmission.com, catalin.marinas@arm.com, mingo@redhat.com,
peterz@infradead.org, liam.howlett@oracle.com,
lorenzo.stoakes@oracle.com, vbabka@suse.cz, jannh@google.com,
hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev,
shakeel.butt@linux.dev, muchun.song@linux.dev,
tglx@linutronix.de, cgroups@vger.kernel.org, x86@kernel.org,
linux-doc@vger.kernel.org, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
mhiramat@kernel.org, rostedt@goodmis.org,
vasily.averin@linux.dev, xhao@linux.alibaba.com, pcc@google.com,
neilb@suse.de, maz@kernel.org
Subject: Re: [PATCH 00/20] Add support for shared PTEs across processes
Date: Wed, 29 Jan 2025 00:59:10 +0000 [thread overview]
Message-ID: <Z5l9XpSntxyxMGKj@casper.infradead.org> (raw)
In-Reply-To: <92f188ed-4f47-427b-b8fd-2c0f76ef129b@oracle.com>
On Tue, Jan 28, 2025 at 04:25:22PM -0800, Anthony Yznaga wrote:
>
> On 1/28/25 4:11 PM, Andrew Morton wrote:
> > On Fri, 24 Jan 2025 15:54:34 -0800 Anthony Yznaga <anthony.yznaga@oracle.com> wrote:
> >
> > > Some of the field deployments commonly see memory pages shared
> > > across 1000s of processes. On x86_64, each page requires a PTE that
> > > is 8 bytes long which is very small compared to the 4K page
> > > size.
> > Dumb question: why aren't these applications using huge pages?
> >
> They often are using hugetlbfs but would also benefit from having page
> tables shared for other kinds of memory such as shmem, tmpfs or dax.
... and the implementation of PMD sharing in hugetlbfs is horrible. In
addition to inverting the locking order (see gigantic comment in rmap.c),
the semantics aren't what the Oracle DB wants, and it's inefficient.
So when we were looking at implementing page table sharing for DAX, we
examined _and rejected_ porting the hugetlbfs approach. We've discussed
this extensively at the last three LSFMM sessions where mshare has been
a topic, and in previous submissions of mshare. So seeing the question
being asked yet again is disheartening.
prev parent reply other threads:[~2025-01-29 0:59 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-24 23:54 [PATCH 00/20] Add support for shared PTEs across processes Anthony Yznaga
2025-01-24 23:54 ` [PATCH 01/20] mm: Add msharefs filesystem Anthony Yznaga
2025-01-25 3:13 ` Randy Dunlap
2025-01-25 20:05 ` Anthony Yznaga
2025-01-25 21:10 ` Matthew Wilcox
2025-01-27 17:01 ` Anthony Yznaga
2025-02-04 1:52 ` Bagas Sanjaya
2025-02-04 16:41 ` Anthony Yznaga
2025-01-24 23:54 ` [PATCH 02/20] mm/mshare: pre-populate msharefs with information file Anthony Yznaga
2025-01-24 23:54 ` [PATCH 03/20] mm/mshare: make msharefs writable and support directories Anthony Yznaga
2025-01-24 23:54 ` [PATCH 04/20] mm/mshare: allocate an mm_struct for msharefs files Anthony Yznaga
2025-01-24 23:54 ` [PATCH 05/20] mm/mshare: Add ioctl support Anthony Yznaga
2025-01-24 23:54 ` [PATCH 06/20] mm/mshare: Add a vma flag to indicate an mshare region Anthony Yznaga
2025-01-24 23:54 ` [PATCH 07/20] mm/mshare: Add mmap support Anthony Yznaga
2025-01-24 23:54 ` [PATCH 08/20] mm/mshare: flush all TLBs when updating PTEs in an mshare range Anthony Yznaga
2025-01-24 23:54 ` [PATCH 09/20] sched/numa: do not scan msharefs vmas Anthony Yznaga
2025-01-24 23:54 ` [PATCH 10/20] mm: add mmap_read_lock_killable_nested() Anthony Yznaga
2025-01-24 23:54 ` [PATCH 11/20] mm: add and use unmap_page_range vm_ops hook Anthony Yznaga
2025-01-24 23:54 ` [PATCH 12/20] mm/mshare: prepare for page table sharing support Anthony Yznaga
2025-01-24 23:54 ` [PATCH 13/20] x86/mm: enable page table sharing Anthony Yznaga
2025-01-24 23:54 ` [PATCH 14/20] mm: create __do_mmap() to take an mm_struct * arg Anthony Yznaga
2025-01-24 23:54 ` [PATCH 15/20] mm: pass the mm in vma_munmap_struct Anthony Yznaga
2025-01-24 23:54 ` [PATCH 16/20] mshare: add MSHAREFS_CREATE_MAPPING Anthony Yznaga
2025-01-24 23:54 ` [PATCH 17/20] mshare: add MSHAREFS_UNMAP Anthony Yznaga
2025-01-24 23:54 ` [PATCH 18/20] mm/mshare: provide a way to identify an mm as an mshare host mm Anthony Yznaga
2025-01-24 23:54 ` [PATCH 19/20] mm/mshare: get memcg from current->mm instead of mshare mm Anthony Yznaga
2025-01-24 23:54 ` [PATCH 20/20] mm/mshare: associate a mem cgroup with an mshare file Anthony Yznaga
2025-01-27 22:33 ` [PATCH 00/20] Add support for shared PTEs across processes Andrew Morton
2025-01-27 23:59 ` Anthony Yznaga
2025-01-28 9:21 ` David Hildenbrand
2025-01-28 7:11 ` Bagas Sanjaya
2025-01-28 19:53 ` Anthony Yznaga
2025-01-28 9:36 ` David Hildenbrand
2025-01-28 19:40 ` Anthony Yznaga
2025-01-29 0:11 ` Andrew Morton
2025-01-29 0:25 ` Anthony Yznaga
2025-01-29 0:59 ` Matthew Wilcox [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=Z5l9XpSntxyxMGKj@casper.infradead.org \
--to=willy@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=anthony.yznaga@oracle.com \
--cc=arnd@arndb.de \
--cc=brauner@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=cgroups@vger.kernel.org \
--cc=corbet@lwn.net \
--cc=dave.hansen@intel.com \
--cc=david@redhat.com \
--cc=ebiederm@xmission.com \
--cc=hannes@cmpxchg.org \
--cc=jannh@google.com \
--cc=jthoughton@google.com \
--cc=khalid@kernel.org \
--cc=kirill@shutemov.name \
--cc=liam.howlett@oracle.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lorenzo.stoakes@oracle.com \
--cc=luto@kernel.org \
--cc=markhemm@googlemail.com \
--cc=maz@kernel.org \
--cc=mhiramat@kernel.org \
--cc=mhocko@kernel.org \
--cc=mingo@redhat.com \
--cc=muchun.song@linux.dev \
--cc=neilb@suse.de \
--cc=pcc@google.com \
--cc=peterz@infradead.org \
--cc=roman.gushchin@linux.dev \
--cc=rostedt@goodmis.org \
--cc=shakeel.butt@linux.dev \
--cc=tglx@linutronix.de \
--cc=vasily.averin@linux.dev \
--cc=vbabka@suse.cz \
--cc=viro@zeniv.linux.org.uk \
--cc=x86@kernel.org \
--cc=xhao@linux.alibaba.com \
/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).