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From: Matthew Wilcox <willy@infradead.org>
To: Mina Almasry <almasrymina@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>,
	David Hildenbrand <david@redhat.com>,
	"Paul E . McKenney" <paulmckrcu@fb.com>,
	Yu Zhao <yuzhao@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Peter Xu <peterx@redhat.com>,
	Ivan Teterevkov <ivan.teterevkov@nutanix.com>,
	Florian Schmidt <florian.schmidt@nutanix.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, linux-doc@vger.kernel.org
Subject: Re: [PATCH v7] mm: Add PM_THP_MAPPED to /proc/pid/pagemap
Date: Sun, 28 Nov 2021 04:10:01 +0000	[thread overview]
Message-ID: <YaMBGQGNLqPd6D6f@casper.infradead.org> (raw)
In-Reply-To: <20211123000102.4052105-1-almasrymina@google.com>

On Mon, Nov 22, 2021 at 04:01:02PM -0800, Mina Almasry wrote:
> Add PM_THP_MAPPED MAPPING to allow userspace to detect whether a given virt
> address is currently mapped by a transparent huge page or not.  Example
> use case is a process requesting THPs from the kernel (via a huge tmpfs
> mount for example), for a performance critical region of memory.  The
> userspace may want to query whether the kernel is actually backing this
> memory by hugepages or not.

But what is userspace going to _do_ differently if the kernel hasn't
backed the memory with huge pages?

  parent reply	other threads:[~2021-11-28  4:21 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-23  0:01 [PATCH v7] mm: Add PM_THP_MAPPED to /proc/pid/pagemap Mina Almasry
2021-11-23  1:10 ` Peter Xu
2021-11-23  1:50 ` David Rientjes
2021-11-23 12:05 ` David Hildenbrand
2021-11-23 20:51 ` Matthew Wilcox
2021-11-23 21:10   ` Mina Almasry
2021-11-23 21:30     ` Matthew Wilcox
2021-11-23 21:47       ` Mina Almasry
2021-11-23 22:03         ` Matthew Wilcox
2021-11-23 22:23           ` Mina Almasry
2021-11-23 22:59             ` Matthew Wilcox
2021-11-23 23:16               ` Mina Almasry
2021-11-28  4:10 ` Matthew Wilcox [this message]
2021-12-14  0:22   ` Mina Almasry
2022-01-04 23:04     ` Mina Almasry
2022-01-05  4:39       ` Matthew Wilcox
2022-01-11 23:35       ` William Kucharski

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