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From: "Chris Friesen" <cfriesen@nortel.com>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com,
	npiggin@suse.de, chris.mason@oracle.com, kurt.hackel@oracle.com,
	dave.mccracken@oracle.com, Avi Kivity <avi@redhat.com>,
	jeremy@goop.org, Rik van Riel <riel@redhat.com>,
	alan@lxorguk.ukuu.org.uk, Rusty Russell <rusty@rustcorp.com.au>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	akpm@osdl.org, Marcelo Tosatti <mtosatti@redhat.com>,
	Balbir Singh <balbir@linux.vnet.ibm.com>,
	tmem-devel@oss.oracle.com, sunil.mushran@oracle.com,
	linux-mm@kvack.org, Himanshu Raj <rhim@microsoft.com>
Subject: Re: [RFC] transcendent memory for Linux
Date: Mon, 22 Jun 2009 08:31:02 -0600	[thread overview]
Message-ID: <4A3F95A6.5040503@nortel.com> (raw)
In-Reply-To: <cd40cd91-66e9-469d-b079-3a899a3ccadb@default>

Dan Magenheimer wrote:

> What if there was a class of memory that is of unknown
> and dynamically variable size, is addressable only indirectly
> by the kernel, can be configured either as persistent or
> as "ephemeral" (meaning it will be around for awhile, but
> might disappear without warning), and is still fast enough
> to be synchronously accessible?
> 
> We call this latter class "transcendent memory"

While true that this memory is "exceeding usual limits", the more
important criteria is that it may disappear.

It might be clearer to just call it "ephemeral memory".

There is going to be some overhead due to the extra copying, and at
times there could be two copies of data in memory.  It seems possible
that certain apps right a the borderline could end up running slower
because they can't fit in the regular+ephemeral memory due to the
duplication, while the same amount of memory used normally could have
been sufficient.

I suspect trying to optimize management of this could be difficult.

Chris

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  parent reply	other threads:[~2009-06-22 14:30 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-06-19 23:53 Dan Magenheimer
2009-06-20  1:35 ` [RFC PATCH 0/4] transcendent memory ("tmem") " Dan Magenheimer
2009-06-20  1:35 ` [RFC PATCH 1/4] tmem: infrastructure for tmem layer Dan Magenheimer
2009-06-20  1:50   ` Rik van Riel
2009-06-20  1:35 ` [RFC PATCH 2/4] tmem: precache implementation (layered on tmem) Dan Magenheimer
2009-06-20  2:28   ` Rik van Riel
2009-06-20  1:36 ` [RFC PATCH 3/4] tmem: preswap " Dan Magenheimer
2009-06-20  1:36 ` [RFC PATCH 4/4] tmem: interface code for tmem on top of xen Dan Magenheimer
2009-06-22 11:27 ` [RFC] transcendent memory for Linux Martin Schwidefsky
2009-06-22 20:41   ` Dan Magenheimer
2009-06-22 14:31 ` Chris Friesen [this message]
2009-06-22 20:50   ` Dan Magenheimer
2009-06-24 15:04 ` Pavel Machek
2009-06-29 14:34   ` Dan Magenheimer
2009-06-29 20:36     ` Pavel Machek
2009-06-29 21:13       ` Dan Magenheimer
2009-06-29 21:23         ` Jeremy Fitzhardinge
2009-06-29 21:57           ` Dan Magenheimer
2009-06-29 22:15             ` Jeremy Fitzhardinge
2009-06-30 21:21               ` Dan Magenheimer
2009-06-30 22:46                 ` Jeremy Fitzhardinge
2009-07-01 23:02                   ` Dan Magenheimer
2009-07-01 23:31                     ` Jeremy Fitzhardinge
2009-07-02  6:38                     ` Pavel Machek
2009-07-02 14:03                       ` Dan Magenheimer
2009-06-27 13:18 ` Linus Walleij
2009-06-28  7:42   ` Avi Kivity
2009-06-29 14:44   ` Dan Magenheimer
2009-07-01  3:41     ` Roland Dreier

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