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Mon, 22 Jan 2024 06:35:03 -0800 (PST) MIME-Version: 1.0 References: <20240118120347.61817-1-ioworker0@gmail.com> In-Reply-To: From: Lance Yang Date: Mon, 22 Jan 2024 22:34:51 +0800 Message-ID: Subject: Re: [PATCH v2 1/1] mm/madvise: add MADV_F_COLLAPSE_LIGHT to process_madvise() To: Michal Hocko , "Zach O'Keefe" Cc: akpm@linux-foundation.org, david@redhat.com, songmuchun@bytedance.com, shy828301@gmail.com, peterx@redhat.com, mknyszek@google.com, minchan@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: nwhr1xofhmbo3c1qfgpj3iopax69bxwp X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: F1C63140016 X-HE-Tag: 1705934103-648010 X-HE-Meta: U2FsdGVkX186rzuq7uE8ULGpUEIOXYzuKHR46syOeDxbWCcKLBBOCEu3Xc2vFxD/UaGzakNMlXwK5JAIB/lFaxS8d/eM0kSOg67fVkH7GIzLY21EMoGtZi7zHbzC4xEoYMhhOA1yA78PFZzgxlsRtNLcQIgYw8G0u0/F59AyUU5WVdIYcR7l+eGNWf4HSvcM0KWzpzjNdUCa37cF+WXp/YK46XiTGVbvtGJXfmtMeRWZQ+lAPSmVB2tGUozThM3tZlrlUohku/NIKU9vFvjTd8wNdAQzwlfzfGAS7b9pnu+GWQLXppPfp5shdbvWG9PFjvkB0NnZXTgnEMdfQkOj0PIaTPXzY1eK5QbW4Y55xmzVRqyjUZcsjYxagz+u5xwklAOVXrO13cucTVGjw8qpMV6rI0gOLnQQ9JYvGv6yvevZpYxJWW+GUnJr5ppoQOrDuqrtvKFN9eJ7GKZJCpUz65WBOSMRbfsmDkeSnEg16qizeJvaTEfKatsQQ05UW4QEcoejmZ/p8m/efMIMt8/NL3kPg3vtW6pU+E433HdZ2TZYRuL6duWcUQJU3MyyNtwzuiCz8fB/qmING6JihcwiZ2dpDHhRH/x1t8+iDguCt0RSgTC0OY1Gd8oeoIGlS11XNpMQJJaUoBzB7N7KVz4zGL3prF4w+SMnhukwqfIp5+YkgQrvrx73N0fsfdHJcXqME25nfV5T/FS4iE2K+kesLSuykOF6bUjUH/jU/lz6EGkqubyGePBDqHCtX5YuEFlN/6rMMHlU1ZS0tIpAUXm4/UlztPy3IEkXwhcff42AKHY814SoH+5sx5tf3+oOTeugvUjl8J5i9ZAoU3BOXVKJh71SNOImBwgXTKorgz/Sze7fwRDYWAYblIEJ6Yk7/LHFP3AhRA8ckdQHLaozirwNQgGgx86QhEFRkOL/XqD28SM2mjEY4+yGHHZHT/TeYPLlZist/4goCoZXG7Gh3tL qs/I4g4S 6gfefeUzuAQDm7HwGlCtShAZF8ZnzFRPpTuVJGdf2vr7E088XiOicu0C9U/dvK+O4uCmA7HsI4y4UoctQyLPNXMxreb1nuClKzRIjBYuuI1zriTdbQmb8yp0e7dBOt+8xNrCqyK2fXrKfubWcuC4IFxrY/rWlJZLzfZgBljyQJ80t4tr7IpMKTXLopDTYdahHwARwlT2OOUVBgpss98h9N9WnRzPW+sxsc2op5vJEiZzTrbZCqBC/nGLrGqhJdjjCO0SrZMtebl//XeCzx6xnqOBAQr8nc+rrhmPKs9EtwZl+f/jmSJDwxIrb5LmgEa5yqq14/cXbyHHOH13p883g4hsthqyOHI/3k4IeNgM4n5JCrYNg+vYG+EAPf3UUiW3yhw9U7uUvxZ6h9LuYknQELMW0gdUn966kmPcANxjGCwiUET04678eKPQxOByHm4zoYo8j5aAJwWKx/OS9Mhv4eQrwePmEpTHqRboYzW7ahqM3eWo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000046, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hey Zach, What do you think about the semantic? Thanks, Lance On Mon, Jan 22, 2024 at 10:14=E2=80=AFPM Lance Yang w= rote: > > On Mon, Jan 22, 2024 at 9:50=E2=80=AFPM Michal Hocko wr= ote: > > > > On Sat 20-01-24 10:09:32, Lance Yang wrote: > > [...] > > > Hey Michal, > > > > > > Thanks for your suggestion! > > > > > > It seems that the implementation should try but not too hard aligns w= ell > > > with my desired behavior. > > > > The problem I have with this semantic is that it is really hard to > > define and then stick with. Our implementation might change over time > > and what somebody considers good ATM might turn int "trying harder than > > I wanted" later on. > > > > > Non-blocking in general is also a great idea. > > > Perhaps in the future, we can add a MADV_F_COLLAPSE_NOBLOCK > > > flag for scenarios where latency is extremely critical. > > > > Non blocking semantic is much easier to define and maintain. The actual > > allocation/compaction implementation might change as well over time but > > the userspace at least knows that the request will not block waiting fo= r > > any required resources. > > I appreciate your insights! > > It makes sense that a non-blocking semantic is easier to define and maint= ain, > providing userspace with the certainty that requests won=E2=80=99t be blo= cked. > > Thanks, > Lance > > > > > -- > > Michal Hocko > > SUSE Labs