From: "Zach O'Keefe" <zokeefe@google.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: David Rientjes <rientjes@google.com>,
Yang Shi <shy828301@gmail.com>,
Alex Shi <alex.shi@linux.alibaba.com>,
David Hildenbrand <david@redhat.com>,
Michal Hocko <mhocko@suse.com>,
Pasha Tatashin <pasha.tatashin@soleen.com>,
SeongJae Park <sj@kernel.org>, Song Liu <songliubraving@fb.com>,
Vlastimil Babka <vbabka@suse.cz>, Zi Yan <ziy@nvidia.com>,
Linux MM <linux-mm@kvack.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Arnd Bergmann <arnd@arndb.de>,
Axel Rasmussen <axelrasmussen@google.com>,
Chris Kennelly <ckennelly@google.com>,
Chris Zankel <chris@zankel.net>, Helge Deller <deller@gmx.de>,
Hugh Dickins <hughd@google.com>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
"James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
Jens Axboe <axboe@kernel.dk>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Matt Turner <mattst88@gmail.com>,
Max Filippov <jcmvbkbc@gmail.com>,
Miaohe Lin <linmiaohe@huawei.com>,
Minchan Kim <minchan@kernel.org>,
Patrick Xia <patrickx@google.com>,
Pavel Begunkov <asml.silence@gmail.com>,
Peter Xu <peterx@redhat.com>,
Richard Henderson <rth@twiddle.net>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Subject: Re: [RFC PATCH 12/14] mm/madvise: introduce batched madvise(MADV_COLLPASE) collapse
Date: Thu, 10 Mar 2022 16:06:58 -0800 [thread overview]
Message-ID: <CAAa6QmQm8b8w6X98pc-MV+wMwKyQbXjMOjcxZS_C2Yh-WoiPag@mail.gmail.com> (raw)
In-Reply-To: <YipcsMAgdCrnC5Ip@casper.infradead.org>
On Thu, Mar 10, 2022 at 12:17 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Thu, Mar 10, 2022 at 11:26:15AM -0800, David Rientjes wrote:
> > One concern might be the queueing of read locks needed for page faults
> > behind a collapser of a long range of memory that is otherwise looping
> > and repeatedly taking the write lock.
>
> I would have thought that _not_ batching would improve this situation.
> Unless our implementation of rwsems has changed since the last time I
> looked, dropping-and-reacquiring a rwsem while there are pending readers
> means you go to the end of the line and they all get to handle their
> page faults.
>
Hey Matthew, thanks for the review / feedback.
I don't have great intuition here, so I'll try to put together a
simple synthetic test to get some data. Though the code would be
different, I can functionally approximate a non-batched approach with
a batch size of 1, and compare that against N.
My file-backed patches likewise weren't able to take advantage of
batching outside mmap lock contention, so the data should equally
apply there.
next prev parent reply other threads:[~2022-03-11 0:07 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-08 21:34 [RFC PATCH 00/14] mm: userspace hugepage collapse Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 01/14] mm/rmap: add mm_find_pmd_raw helper Zach O'Keefe
2022-03-09 22:48 ` Yang Shi
2022-03-08 21:34 ` [RFC PATCH 02/14] mm/khugepaged: add struct collapse_control Zach O'Keefe
2022-03-09 22:53 ` Yang Shi
2022-03-08 21:34 ` [RFC PATCH 03/14] mm/khugepaged: add __do_collapse_huge_page() helper Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 04/14] mm/khugepaged: separate khugepaged_scan_pmd() scan and collapse Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 05/14] mm/khugepaged: add mmap_assert_locked() checks to scan_pmd() Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 06/14] mm/khugepaged: add hugepage_vma_revalidate_pmd_count() Zach O'Keefe
2022-03-09 23:15 ` Yang Shi
2022-03-08 21:34 ` [RFC PATCH 07/14] mm/khugepaged: add vm_flags_ignore to hugepage_vma_revalidate_pmd_count() Zach O'Keefe
2022-03-09 23:17 ` Yang Shi
2022-03-10 0:00 ` Zach O'Keefe
2022-03-10 0:41 ` Yang Shi
2022-03-10 1:09 ` Zach O'Keefe
2022-03-10 2:16 ` Yang Shi
2022-03-10 15:50 ` Zach O'Keefe
2022-03-10 18:17 ` Yang Shi
2022-03-10 18:46 ` David Rientjes
2022-03-10 18:58 ` Zach O'Keefe
2022-03-10 19:54 ` Yang Shi
2022-03-10 20:24 ` Zach O'Keefe
2022-03-10 18:53 ` Zach O'Keefe
2022-03-10 15:56 ` David Hildenbrand
2022-03-10 18:39 ` Zach O'Keefe
2022-03-10 18:54 ` David Rientjes
2022-03-21 14:27 ` Michal Hocko
2022-03-08 21:34 ` [RFC PATCH 08/14] mm/thp: add madv_thp_vm_flags to __transparent_hugepage_enabled() Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 09/14] mm/khugepaged: record SCAN_PAGE_COMPOUND when scan_pmd() finds THP Zach O'Keefe
2022-03-09 23:40 ` Yang Shi
2022-03-10 0:46 ` Zach O'Keefe
2022-03-10 2:05 ` Yang Shi
2022-03-10 8:37 ` Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 10/14] mm/khugepaged: rename khugepaged-specific/not functions Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 11/14] mm/madvise: introduce MADV_COLLAPSE sync hugepage collapse Zach O'Keefe
2022-03-09 23:43 ` Yang Shi
2022-03-10 1:11 ` Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 12/14] mm/madvise: introduce batched madvise(MADV_COLLPASE) collapse Zach O'Keefe
2022-03-10 0:06 ` Yang Shi
2022-03-10 19:26 ` David Rientjes
2022-03-10 20:16 ` Matthew Wilcox
2022-03-11 0:06 ` Zach O'Keefe [this message]
2022-03-25 16:51 ` Zach O'Keefe
2022-03-25 19:54 ` Yang Shi
2022-03-08 21:34 ` [RFC PATCH 13/14] mm/madvise: add __madvise_collapse_*_batch() actions Zach O'Keefe
2022-03-08 21:34 ` [RFC PATCH 14/14] mm/madvise: add process_madvise(MADV_COLLAPSE) Zach O'Keefe
2022-03-21 14:32 ` [RFC PATCH 00/14] mm: userspace hugepage collapse Zi Yan
2022-03-21 14:51 ` Zach O'Keefe
2022-03-21 14:37 ` Michal Hocko
2022-03-21 15:46 ` Zach O'Keefe
2022-03-22 12:11 ` Michal Hocko
2022-03-22 15:53 ` Zach O'Keefe
2022-03-29 12:24 ` Michal Hocko
2022-03-30 0:36 ` Zach O'Keefe
2022-03-22 6:40 ` Zach O'Keefe
2022-03-22 12:05 ` Michal Hocko
2022-03-23 13:30 ` Zach O'Keefe
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