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From: Michal Hocko <mhocko@kernel.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Minchan Kim <minchan@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	linux-api@vger.kernel.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>,
	oleksandr@redhat.com, hdanton@sina.com, lizeb@google.com,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH v3 1/5] mm: introduce MADV_COLD
Date: Thu, 27 Jun 2019 16:02:03 +0200	[thread overview]
Message-ID: <20190627140203.GB5303@dhcp22.suse.cz> (raw)
In-Reply-To: <343599f9-3d99-b74f-1732-368e584fa5ef@intel.com>

On Thu 27-06-19 06:13:36, Dave Hansen wrote:
> On 6/27/19 4:54 AM, Minchan Kim wrote:
> > This patch introduces the new MADV_COLD hint to madvise(2) syscall.
> > MADV_COLD 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.
> > 
> > It works for every LRU pages like MADV_[DONTNEED|FREE]. IOW, It moves
> > 
> > 	active file page -> inactive file LRU
> > 	active anon page -> inacdtive anon LRU
> 
> Is the LRU behavior part of the interface or the implementation?
> 
> I ask because we've got something in between tossing something down the
> LRU and swapping it: page migration.  Specifically, on a system with
> slower memory media (like persistent memory) we just migrate a page
> instead of discarding it at reclaim:

But we already do have interfaces for migrating the memory
(move_pages(2)). Why should this interface duplicate that interface?
I believe the only purpose of these two new madvise modes is to provide
a non-destructive MADV_{DONTNEED,FREE} alteternatives. In other words,
pageout vs. age interface.
-- 
Michal Hocko
SUSE Labs


  reply	other threads:[~2019-06-27 14:02 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-27 11:54 [PATCH v3 0/5] Introduce MADV_COLD and MADV_PAGEOUT Minchan Kim
2019-06-27 11:54 ` [PATCH v3 1/5] mm: introduce MADV_COLD Minchan Kim
2019-06-27 13:13   ` Dave Hansen
2019-06-27 14:02     ` Michal Hocko [this message]
2019-06-27 14:36       ` Dave Hansen
2019-06-27 14:53         ` Michal Hocko
2019-06-27 23:56           ` Minchan Kim
2019-07-01  7:35             ` Minchan Kim
2019-07-09  9:19               ` Michal Hocko
2019-06-27 23:46     ` Minchan Kim
2019-06-27 11:54 ` [PATCH v3 2/5] mm: change PAGEREF_RECLAIM_CLEAN with PAGE_REFRECLAIM Minchan Kim
2019-06-27 11:54 ` [PATCH v3 3/5] mm: account nr_isolated_xxx in [isolate|putback]_lru_page Minchan Kim
2019-07-09  9:38   ` Michal Hocko
2019-06-27 11:54 ` [PATCH v3 4/5] mm: introduce MADV_PAGEOUT Minchan Kim
2019-07-09  9:55   ` Michal Hocko
2019-07-10 10:48     ` Minchan Kim
2019-07-10 11:16       ` Michal Hocko
2019-07-10 11:53         ` Minchan Kim
2019-07-10 19:47           ` Michal Hocko
2019-07-11  0:25             ` Minchan Kim
2019-06-27 11:54 ` [PATCH v3 5/5] mm: factor out pmd young/dirty bit handling and THP split Minchan Kim
2019-07-09 14:10   ` Michal Hocko
2019-07-10 10:56     ` Minchan Kim
2019-06-27 18:06 ` [PATCH v3 0/5] Introduce MADV_COLD and MADV_PAGEOUT Kirill A. Shutemov
2019-06-27 23:12   ` Minchan Kim
2019-07-01  7:38 ` Minchan Kim
2019-07-01 10:22   ` Michal Hocko

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