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From: Minchan Kim <minchan@kernel.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Tim Murray <timmurray@google.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Daniel Colascione <dancol@google.com>,
	Shakeel Butt <shakeelb@google.com>,
	Sonny Rao <sonnyrao@google.com>,
	Brian Geffon <bgeffon@google.com>,
	linux-api@vger.kernel.org
Subject: Re: [RFC 1/7] mm: introduce MADV_COOL
Date: Tue, 21 May 2019 07:54:19 +0900
Message-ID: <20190520225419.GA10039@google.com> (raw)
In-Reply-To: <20190520081621.GV6836@dhcp22.suse.cz>

On Mon, May 20, 2019 at 10:16:21AM +0200, Michal Hocko wrote:
> [CC linux-api]

Thanks, Michal. I forgot to add it.

> 
> On Mon 20-05-19 12:52:48, Minchan Kim wrote:
> > When a process expects no accesses to a certain memory range
> > it could hint kernel that the pages can be reclaimed
> > when memory pressure happens but data should be preserved
> > for future use.  This could reduce workingset eviction so it
> > ends up increasing performance.
> > 
> > This patch introduces the new MADV_COOL hint to madvise(2)
> > syscall. MADV_COOL can be used by a process to mark a memory range
> > as not expected to be used in the near future. The hint can help
> > kernel in deciding which pages to evict early during memory
> > pressure.
> 
> I do not want to start naming fight but MADV_COOL sounds a bit
> misleading. Everybody thinks his pages are cool ;). Probably MADV_COLD
> or MADV_DONTNEED_PRESERVE.

Thanks for the suggestion. Since I got several suggestions, Let's discuss
them all at once in cover-letter.

> 
> > Internally, it works via deactivating memory from active list to
> > inactive's head so when the memory pressure happens, they will be
> > reclaimed earlier than other active pages unless there is no
> > access until the time.
> 
> Could you elaborate about the decision to move to the head rather than
> tail? What should happen to inactive pages? Should we move them to the
> tail? Your implementation seems to ignore those completely. Why?

Normally, inactive LRU could have used-once pages without any mapping
to user's address space. Such pages would be better candicate to
reclaim when the memory pressure happens. With deactivating only
active LRU pages of the process to the head of inactive LRU, we will
keep them in RAM longer than used-once pages and could have more chance
to be activated once the process is resumed.

> 
> What should happen for shared pages? In other words do we want to allow
> less privileged process to control evicting of shared pages with a more
> privileged one? E.g. think of all sorts of side channel attacks. Maybe
> we want to do the same thing as for mincore where write access is
> required.

It doesn't work with shared pages(ie, page_mapcount > 1). I will add it
in the description.

> -- 
> Michal Hocko
> SUSE Labs


  parent reply index

Thread overview: 145+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-20  3:52 [RFC 0/7] introduce memory hinting API for external process Minchan Kim
2019-05-20  3:52 ` [RFC 1/7] mm: introduce MADV_COOL Minchan Kim
2019-05-20  8:16   ` Michal Hocko
2019-05-20  8:19     ` Michal Hocko
2019-05-20 15:08       ` Suren Baghdasaryan
2019-05-20 22:55       ` Minchan Kim
2019-05-20 22:54     ` Minchan Kim [this message]
2019-05-21  6:04       ` Michal Hocko
2019-05-21  9:11         ` Minchan Kim
2019-05-21 10:05           ` Michal Hocko
2019-05-28  8:53   ` Hillf Danton
2019-05-28 10:58   ` Minchan Kim
2019-05-20  3:52 ` [RFC 2/7] mm: change PAGEREF_RECLAIM_CLEAN with PAGE_REFRECLAIM Minchan Kim
2019-05-20 16:50   ` Johannes Weiner
2019-05-20 22:57     ` Minchan Kim
2019-05-20  3:52 ` [RFC 3/7] mm: introduce MADV_COLD Minchan Kim
2019-05-20  8:27   ` Michal Hocko
2019-05-20 23:00     ` Minchan Kim
2019-05-21  6:08       ` Michal Hocko
2019-05-21  9:13         ` Minchan Kim
2019-05-28 14:54   ` Hillf Danton
2019-05-30  0:45   ` Minchan Kim
2019-05-20  3:52 ` [RFC 4/7] mm: factor out madvise's core functionality Minchan Kim
2019-05-20 14:26   ` Oleksandr Natalenko
2019-05-21  1:26     ` Minchan Kim
2019-05-21  6:36       ` Oleksandr Natalenko
2019-05-21  6:50         ` Michal Hocko
2019-05-21  7:06           ` Oleksandr Natalenko
2019-05-21 10:52             ` Minchan Kim
2019-05-21 11:00               ` Michal Hocko
2019-05-21 11:24                 ` Minchan Kim
2019-05-21 11:32                   ` Michal Hocko
2019-05-21 10:49         ` Minchan Kim
2019-05-21 10:55           ` Michal Hocko
2019-05-20  3:52 ` [RFC 5/7] mm: introduce external memory hinting API Minchan Kim
2019-05-20  9:18   ` Michal Hocko
2019-05-21  2:41     ` Minchan Kim
2019-05-21  6:17       ` Michal Hocko
2019-05-21 10:32         ` Minchan Kim
2019-05-21  9:01   ` Christian Brauner
2019-05-21 11:35     ` Minchan Kim
2019-05-21 11:51       ` Christian Brauner
2019-05-21 15:31   ` Oleg Nesterov
2019-05-27  7:43     ` Minchan Kim
2019-05-27 15:12       ` Oleg Nesterov
2019-05-27 23:33         ` Minchan Kim
2019-05-28  7:23           ` Michal Hocko
2019-05-29  3:41   ` Hillf Danton
2019-05-30  0:38   ` Minchan Kim
2019-05-20  3:52 ` [RFC 6/7] mm: extend process_madvise syscall to support vector arrary Minchan Kim
2019-05-20  9:22   ` Michal Hocko
2019-05-21  2:48     ` Minchan Kim
2019-05-21  6:24       ` Michal Hocko
2019-05-21 10:26         ` Minchan Kim
2019-05-21 10:37           ` Michal Hocko
2019-05-27  7:49             ` Minchan Kim
2019-05-29 10:08               ` Daniel Colascione
2019-05-29 10:33                 ` Michal Hocko
2019-05-30  2:17                   ` Minchan Kim
2019-05-30  6:57                     ` Michal Hocko
2019-05-30  8:02                       ` Minchan Kim
2019-05-30 16:19                         ` Daniel Colascione
2019-05-30 18:47                         ` Michal Hocko
2019-05-29  4:14   ` Hillf Danton
2019-05-30  0:35   ` Minchan Kim
2019-05-20  3:52 ` [RFC 7/7] mm: madvise support MADV_ANONYMOUS_FILTER and MADV_FILE_FILTER Minchan Kim
2019-05-20  9:28   ` Michal Hocko
2019-05-21  2:55     ` Minchan Kim
2019-05-21  6:26       ` Michal Hocko
2019-05-27  7:58         ` Minchan Kim
2019-05-27 12:44           ` Michal Hocko
2019-05-28  3:26             ` Minchan Kim
2019-05-28  6:29               ` Michal Hocko
2019-05-28  8:13                 ` Minchan Kim
2019-05-28  8:31                   ` Daniel Colascione
2019-05-28  8:49                     ` Minchan Kim
2019-05-28  9:08                       ` Michal Hocko
2019-05-28  9:39                         ` Daniel Colascione
2019-05-28 10:33                           ` Michal Hocko
2019-05-28 11:21                             ` Daniel Colascione
2019-05-28 11:49                               ` Michal Hocko
2019-05-28 12:11                                 ` Daniel Colascione
2019-05-28 12:32                                   ` Michal Hocko
2019-05-28 10:32                         ` Minchan Kim
2019-05-28 10:41                           ` Michal Hocko
2019-05-28 11:12                             ` Minchan Kim
2019-05-28 11:28                               ` Michal Hocko
2019-05-28 11:42                                 ` Daniel Colascione
2019-05-28 11:56                                   ` Michal Hocko
2019-05-28 12:18                                     ` Daniel Colascione
2019-05-28 12:38                                       ` Michal Hocko
2019-05-28 12:10                                   ` Minchan Kim
2019-05-28 11:44                                 ` Minchan Kim
2019-05-28 11:51                                   ` Daniel Colascione
2019-05-28 12:06                                   ` Michal Hocko
2019-05-28 12:22                                     ` Minchan Kim
2019-05-28 11:28                             ` Daniel Colascione
2019-05-21 15:33       ` Johannes Weiner
2019-05-22  1:50         ` Minchan Kim
2019-05-29  4:36   ` Hillf Danton
2019-05-30  1:00   ` Minchan Kim
2019-05-20  6:37 ` [RFC 0/7] introduce memory hinting API for external process Anshuman Khandual
2019-05-20 16:59   ` Tim Murray
2019-05-21  2:55     ` Anshuman Khandual
2019-05-21  5:14       ` Minchan Kim
2019-05-21 10:34       ` Michal Hocko
2019-05-28 10:50         ` Anshuman Khandual
2019-05-21 12:56       ` Shakeel Butt
2019-05-22  4:15         ` Brian Geffon
2019-05-22  4:23         ` Brian Geffon
2019-05-20  9:28 ` Michal Hocko
2019-05-20 14:42 ` Oleksandr Natalenko
2019-05-21  2:56   ` Minchan Kim
2019-05-20 16:46 ` Johannes Weiner
2019-05-21  4:39   ` Minchan Kim
2019-05-21  6:32     ` Michal Hocko
2019-05-21  1:44 ` Matthew Wilcox
2019-05-21  5:01   ` Minchan Kim
2019-05-21  6:34   ` Michal Hocko
2019-05-21  8:42 ` Christian Brauner
2019-05-21 11:05   ` Minchan Kim
2019-05-21 11:30     ` Christian Brauner
2019-05-21 11:39       ` Christian Brauner
2019-05-22  5:11         ` Daniel Colascione
2019-05-22  8:22           ` Christian Brauner
2019-05-22 13:16             ` Daniel Colascione
2019-05-22 14:52               ` Christian Brauner
2019-05-22 15:17                 ` Daniel Colascione
2019-05-22 15:48                   ` Christian Brauner
2019-05-22 15:57                     ` Daniel Colascione
2019-05-22 16:01                       ` Christian Brauner
2019-05-22 16:01                         ` Daniel Colascione
2019-05-23 13:07                           ` Minchan Kim
2019-05-27  8:06                             ` Minchan Kim
2019-05-21 11:41       ` Minchan Kim
2019-05-21 12:04         ` Christian Brauner
2019-05-21 12:15           ` Oleksandr Natalenko
2019-05-21 12:53 ` Shakeel Butt
2019-05-28 12:15 [RFC 1/7] mm: introduce MADV_COOL Hillf Danton
2019-05-28 12:39 ` Minchan Kim
2019-05-28 15:38 Hillf Danton
2019-05-28 16:11 ` Michal Hocko
2019-05-29  2:40 Hillf Danton
2019-05-29  5:05 ` Michal Hocko
2019-05-29  8:52 Hillf Danton

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