From: Gal Pressman <galpress@amazon.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: <aarcange@redhat.com>, <akpm@linux-foundation.org>,
<gokhale2@llnl.gov>, <hch@lst.de>, <jack@suse.cz>,
<jannh@google.com>, <jhubbard@nvidia.com>, <kirill@shutemov.name>,
<ktkhai@virtuozzo.com>, <leonro@nvidia.com>,
<linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
<mcfadden8@llnl.gov>, <oleg@redhat.com>, <peterx@redhat.com>,
<torvalds@linux-foundation.org>, <wzam@amazon.com>,
<yang.shi@linux.alibaba.com>
Subject: Re: [PATCH 1/4] mm: Trial do_wp_page() simplification
Date: Wed, 3 Feb 2021 16:47:20 +0200 [thread overview]
Message-ID: <e2f897f8-b6af-0d4a-6a69-b47da5564165@amazon.com> (raw)
In-Reply-To: <20210203140015.GP4718@ziepe.ca>
On 03/02/2021 16:00, Jason Gunthorpe wrote:
> On Wed, Feb 03, 2021 at 02:43:58PM +0200, Gal Pressman wrote:
>>> On Tue, Feb 02, 2021 at 12:05:36PM -0500, Peter Xu wrote:
>>>
>>>>> Gal, you could also MADV_DONTFORK this range if you are explicitly
>>>>> allocating them via special mmap.
>>>>
>>>> Yeah I wanted to mention this one too but I just forgot when reply: the issue
>>>> thread previously pasted smells like some people would like to drop
>>>> MADV_DONTFORK, but if it's able to still be applied I don't know why
>>>> not..
>>>
>>> I want to drop the MADV_DONTFORK for dynamic data memory allocated by
>>> the application layers (eg with malloc) without knowledge of how they
>>> will be used.
>>>
>>> This case is a buffer internal to the communication system that we
>>> know at allocation time how it will be used; so an explicit,
>>> deliberate, MADV_DONTFORK is fine
>>
>> We are referring to libfabric's bounce buffers, correct?
>> Libfabric could be considered as the "app" here, it's not clear why these
>> buffers should be DONTFORK'd before ibv_reg_mr() but others don't.
>
> I assumed they were internal to the EFA code itself.
The hugepages allocation is part of libfabric generic bufpool implementation:
https://github.com/ofiwg/libfabric/blob/cde8665ca5ec2fb957260490d0c8700d8ac69863/include/linux/osd.h#L64
I guess we could madvise them at the libfabric provider's layer.
>> Anyway, it should be simple enough to madvise them after allocation, although I
>> think it's part of libfabric's generic code (which isn't necessarily used on
>> top of rdma-core).
>
> Ah, so that is a reasonable justification for wanting to fix this in
> the kernel..
>
> Lets give Peter some time first.
>
> The other direction to validate this approach is to remove the
> MAP_HUGETLB flags and rely on THP instead, and/or mark them as
> MAP_SHARED.
>
> I'm not sure generic code should be use using MAP_HUGETLB..
It's using MAP_HUGETLB but has a fallback in case it fails:
ret = ofi_alloc_hugepage_buf((void **) &buf_region->alloc_region,
pool->alloc_size);
/* If we can't allocate huge pages, fall back to normal
* allocations for all future attempts.
*/
if (ret) {
pool->attr.flags &= ~OFI_BUFPOOL_HUGEPAGES;
goto retry;
}
buf_region->flags = OFI_BUFPOOL_HUGEPAGES;
> This would be enough to confirm that everything else is working as
> expected
Agree.
next prev parent reply other threads:[~2021-02-03 14:48 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 14:40 [PATCH 1/4] mm: Trial do_wp_page() simplification Gal Pressman
2021-02-02 16:31 ` Peter Xu
2021-02-02 16:44 ` Jason Gunthorpe
2021-02-02 17:05 ` Peter Xu
2021-02-02 17:13 ` Jason Gunthorpe
2021-02-03 12:43 ` Gal Pressman
2021-02-03 14:00 ` Jason Gunthorpe
2021-02-03 14:47 ` Gal Pressman [this message]
-- strict thread matches above, loose matches on Subject: below --
2020-08-21 23:49 [PATCH 0/4] mm: Simplfy cow handling Peter Xu
2020-08-21 23:49 ` [PATCH 1/4] mm: Trial do_wp_page() simplification Peter Xu
2020-08-24 8:36 ` Kirill Tkhai
2020-08-24 14:30 ` Jan Kara
2020-08-24 15:37 ` Kirill Tkhai
2020-08-24 18:22 ` Linus Torvalds
2020-09-01 7:01 ` Hugh Dickins
2020-09-14 14:38 ` Jason Gunthorpe
2020-09-14 17:32 ` Linus Torvalds
2020-09-14 18:34 ` Peter Xu
2020-09-14 21:15 ` Peter Xu
2020-09-14 22:55 ` Jason Gunthorpe
2020-09-14 22:59 ` Linus Torvalds
2020-09-14 23:28 ` Jason Gunthorpe
2020-09-15 0:19 ` Linus Torvalds
2020-09-15 14:50 ` Peter Xu
2020-09-15 15:17 ` Peter Xu
2020-09-15 16:05 ` Jason Gunthorpe
2020-09-15 18:29 ` Jason Gunthorpe
2020-09-15 19:13 ` Peter Xu
2020-09-15 19:38 ` Jason Gunthorpe
2020-09-15 21:33 ` Peter Xu
2020-09-15 23:22 ` Jason Gunthorpe
2020-09-16 1:50 ` John Hubbard
2020-09-16 17:48 ` Jason Gunthorpe
2020-09-16 18:46 ` Peter Xu
2020-09-17 11:25 ` Jason Gunthorpe
2020-09-17 18:11 ` Linus Torvalds
2020-09-17 19:38 ` Jason Gunthorpe
2020-09-17 19:51 ` Linus Torvalds
2020-09-18 16:40 ` Peter Xu
2020-09-18 17:16 ` Linus Torvalds
2020-09-18 19:57 ` Peter Xu
2020-09-18 17:32 ` Jason Gunthorpe
2020-09-18 20:40 ` Peter Xu
2020-09-18 20:59 ` Linus Torvalds
2020-09-19 0:28 ` Jason Gunthorpe
2020-09-18 21:06 ` John Hubbard
2020-09-19 0:01 ` Jason Gunthorpe
2020-09-21 8:35 ` Jan Kara
2020-09-21 12:03 ` Jason Gunthorpe
2022-02-16 16:59 ` Oded Gabbay
2022-02-16 17:24 ` Oded Gabbay
2022-02-16 19:04 ` Linus Torvalds
2022-02-16 19:20 ` Oded Gabbay
2022-02-16 19:24 ` David Hildenbrand
2020-09-21 13:42 ` Michal Hocko
2020-09-21 14:18 ` Peter Xu
2020-09-21 14:28 ` Michal Hocko
2020-09-21 14:38 ` Tejun Heo
2020-09-21 14:43 ` Christian Brauner
2020-09-21 14:55 ` Michal Hocko
2020-09-21 15:04 ` Christian Brauner
2020-09-21 16:06 ` Michal Hocko
2020-09-23 7:53 ` Michal Hocko
2020-09-21 14:41 ` Christian Brauner
2020-09-21 14:57 ` Michal Hocko
2020-09-21 16:31 ` Peter Xu
2020-09-17 18:14 ` Peter Xu
2020-09-17 18:26 ` Linus Torvalds
2020-09-17 19:03 ` Peter Xu
2020-09-17 19:42 ` Linus Torvalds
2020-09-17 19:55 ` John Hubbard
2020-09-17 20:06 ` Jason Gunthorpe
2020-09-17 20:19 ` John Hubbard
2020-09-17 20:25 ` Jason Gunthorpe
2020-09-17 20:35 ` Linus Torvalds
2020-09-17 21:40 ` Peter Xu
2020-09-17 22:09 ` Jason Gunthorpe
2020-09-17 22:25 ` Linus Torvalds
2020-09-17 22:48 ` Ira Weiny
2020-09-18 9:36 ` Jan Kara
2020-09-18 9:44 ` Jan Kara
2020-09-18 16:19 ` Jason Gunthorpe
2020-09-15 10:23 ` Leon Romanovsky
2020-09-15 15:56 ` Jason Gunthorpe
2020-09-15 15:03 ` Oleg Nesterov
2020-09-15 16:18 ` Peter Xu
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=e2f897f8-b6af-0d4a-6a69-b47da5564165@amazon.com \
--to=galpress@amazon.com \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=gokhale2@llnl.gov \
--cc=hch@lst.de \
--cc=jack@suse.cz \
--cc=jannh@google.com \
--cc=jgg@ziepe.ca \
--cc=jhubbard@nvidia.com \
--cc=kirill@shutemov.name \
--cc=ktkhai@virtuozzo.com \
--cc=leonro@nvidia.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mcfadden8@llnl.gov \
--cc=oleg@redhat.com \
--cc=peterx@redhat.com \
--cc=torvalds@linux-foundation.org \
--cc=wzam@amazon.com \
--cc=yang.shi@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).