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From: Dan Magenheimer <dan.magenheimer@oracle.com>
To: Minchan Kim <minchan@kernel.org>, John Stultz <john.stultz@linaro.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Android Kernel Team <kernel-team@android.com>,
	Robert Love <rlove@google.com>, Mel Gorman <mel@csn.ul.ie>,
	Hugh Dickins <hughd@google.com>,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	Rik van Riel <riel@redhat.com>,
	Dmitry Adamushko <dmitry.adamushko@gmail.com>,
	Dave Chinner <david@fromorbit.com>, Neil Brown <neilb@suse.de>,
	Andrea Righi <andrea@betterlinux.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Mike Hommey <mh@glandium.org>, Jan Kara <jack@suse.cz>,
	KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
	Michel Lespinasse <walken@google.com>,
	linux-mm@kvack.org
Subject: RE: [PATCH 4/5] [RFC][HACK] Add LRU_VOLATILE support to the VM
Date: Mon, 6 Aug 2012 08:46:18 -0700 (PDT)	[thread overview]
Message-ID: <aa61fb77-258b-4b6f-843f-689bc5c984cc@default> (raw)
In-Reply-To: <20120806030451.GA11468@bbox>

> From: Minchan Kim [mailto:minchan@kernel.org]
> To: John Stultz
> Subject: Re: [PATCH 4/5] [RFC][HACK] Add LRU_VOLATILE support to the VM

Hi Minchan --

Thanks for cc'ing me on this!

> Targets for the LRU list could be following as in future
> 
> 1. volatile pages in this patchset.
> 2. ephemeral pages of tmem
> 3. madivse(DONTNEED)
> 4. fadvise(NOREUSE)
> 5. PG_reclaimed pages
> 6. clean pages if we write CFLRU(clean first LRU)
> 
> So if any guys have objection, please raise your hands
> before further progress.

I agree that the existing shrinker mechanism is too primitive
and the kernel needs to take into account more factors in
deciding how to quickly reclaim pages from a broader set
of sources.  However, I think it is important to ensure
that both the "demand" side and the "supply" side are
studied.  There has to be some kind of prioritization policy
among all the RAM consumers so that a lower-priority
alloc_page doesn't cause a higher-priority "volatile" page
to be consumed.  I suspect this policy will be VERY hard to
define and maintain.

Related, ephemeral pages in tmem are not truly volatile
as there is always at least one tmem data structure pointing
to it.  I haven't followed this thread previously so my apologies
if it already has this, but the LRU_VOLATILE list might
need to support a per-page "garbage collection" callback.

Dan

WARNING: multiple messages have this Message-ID (diff)
From: Dan Magenheimer <dan.magenheimer@oracle.com>
To: Minchan Kim <minchan@kernel.org>, John Stultz <john.stultz@linaro.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Android Kernel Team <kernel-team@android.com>,
	Robert Love <rlove@google.com>, Mel Gorman <mel@csn.ul.ie>,
	Hugh Dickins <hughd@google.com>,
	Dave Hansen <dave@linux.vnet.ibm.com>,
	Rik van Riel <riel@redhat.com>,
	Dmitry Adamushko <dmitry.adamushko@gmail.com>,
	Dave Chinner <david@fromorbit.com>, Neil Brown <neilb@suse.de>,
	Andrea Righi <andrea@betterlinux.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
	Mike Hommey <mh@glandium.org>, Jan Kara <jack@suse.cz>,
	KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
	Michel Lespinasse <walken@google.com>,
	linux-mm@kvack.org
Subject: RE: [PATCH 4/5] [RFC][HACK] Add LRU_VOLATILE support to the VM
Date: Mon, 6 Aug 2012 08:46:18 -0700 (PDT)	[thread overview]
Message-ID: <aa61fb77-258b-4b6f-843f-689bc5c984cc@default> (raw)
In-Reply-To: <20120806030451.GA11468@bbox>

> From: Minchan Kim [mailto:minchan@kernel.org]
> To: John Stultz
> Subject: Re: [PATCH 4/5] [RFC][HACK] Add LRU_VOLATILE support to the VM

Hi Minchan --

Thanks for cc'ing me on this!

> Targets for the LRU list could be following as in future
> 
> 1. volatile pages in this patchset.
> 2. ephemeral pages of tmem
> 3. madivse(DONTNEED)
> 4. fadvise(NOREUSE)
> 5. PG_reclaimed pages
> 6. clean pages if we write CFLRU(clean first LRU)
> 
> So if any guys have objection, please raise your hands
> before further progress.

I agree that the existing shrinker mechanism is too primitive
and the kernel needs to take into account more factors in
deciding how to quickly reclaim pages from a broader set
of sources.  However, I think it is important to ensure
that both the "demand" side and the "supply" side are
studied.  There has to be some kind of prioritization policy
among all the RAM consumers so that a lower-priority
alloc_page doesn't cause a higher-priority "volatile" page
to be consumed.  I suspect this policy will be VERY hard to
define and maintain.

Related, ephemeral pages in tmem are not truly volatile
as there is always at least one tmem data structure pointing
to it.  I haven't followed this thread previously so my apologies
if it already has this, but the LRU_VOLATILE list might
need to support a per-page "garbage collection" callback.

Dan

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  reply	other threads:[~2012-08-06 15:48 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-07-28  3:57 [PATCH 0/5][RFC] Fallocate Volatile Ranges v6 John Stultz
2012-07-28  3:57 ` John Stultz
2012-07-28  3:57 ` [PATCH 1/5] [RFC] Add volatile range management code John Stultz
2012-07-28  3:57   ` John Stultz
2012-08-09  9:46   ` Michel Lespinasse
2012-08-09  9:46     ` Michel Lespinasse
2012-08-09 13:35     ` Andrea Righi
2012-08-09 13:35       ` Andrea Righi
2012-08-09 19:33       ` John Stultz
2012-08-09 19:33         ` John Stultz
2012-08-09 19:39         ` Andrea Righi
2012-08-09 19:39           ` Andrea Righi
2012-08-09 19:11     ` John Stultz
2012-08-09 19:11       ` John Stultz
2012-07-28  3:57 ` [PATCH 2/5] [RFC] tmpfs: Add FALLOC_FL_MARK_VOLATILE/UNMARK_VOLATILE handlers John Stultz
2012-07-28  3:57   ` John Stultz
2012-07-28  3:57 ` [PATCH 3/5] [RFC] ashmem: Convert ashmem to use volatile ranges John Stultz
2012-07-28  3:57   ` John Stultz
2012-07-28  3:57 ` [PATCH 4/5] [RFC][HACK] Add LRU_VOLATILE support to the VM John Stultz
2012-07-28  3:57   ` John Stultz
2012-08-06  3:04   ` Minchan Kim
2012-08-06  3:04     ` Minchan Kim
2012-08-06 15:46     ` Dan Magenheimer [this message]
2012-08-06 15:46       ` Dan Magenheimer
2012-08-07  0:56       ` Minchan Kim
2012-08-07  0:56         ` Minchan Kim
2012-08-07  1:26         ` Dan Magenheimer
2012-08-07  1:26           ` Dan Magenheimer
2012-08-07  1:45           ` Minchan Kim
2012-08-07  1:45             ` Minchan Kim
2012-08-06 20:38     ` John Stultz
2012-08-06 20:38       ` John Stultz
2012-07-28  3:57 ` [PATCH 5/5] [RFC][HACK] Switch volatile/shmem over to LRU_VOLATILE John Stultz
2012-07-28  3:57   ` John Stultz
2012-08-09  9:28 ` [PATCH 0/5][RFC] Fallocate Volatile Ranges v6 Michel Lespinasse
2012-08-09  9:28   ` Michel Lespinasse
2012-08-09 18:45   ` John Stultz
2012-08-09 18:45     ` John Stultz

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