From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Magenheimer <dan.magenheimer@oracle.com>,
Pekka Enberg <penberg@kernel.org>,
Cyclonus J <cyclonusj@gmail.com>,
Sasha Levin <levinsasha928@gmail.com>,
Christoph Hellwig <hch@infradead.org>,
David Rientjes <rientjes@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Konrad Wilk <konrad.wilk@oracle.com>,
Jeremy Fitzhardinge <jeremy@goop.org>,
Seth Jennings <sjenning@linux.vnet.ibm.com>,
ngupta@vflare.org, Chris Mason <chris.mason@oracle.com>,
JBeulich@novell.com, Dave Hansen <dave@linux.vnet.ibm.com>,
Jonathan Corbet <corbet@lwn.net>
Subject: Re: [GIT PULL] mm: frontswap (for 3.2 window)
Date: Tue, 01 Nov 2011 14:16:30 +0400 [thread overview]
Message-ID: <1320142590.7701.64.camel@dabdike> (raw)
In-Reply-To: <20111031181651.GF3466@redhat.com>
On Mon, 2011-10-31 at 19:16 +0100, Andrea Arcangeli wrote:
> On Fri, Oct 28, 2011 at 08:21:31AM -0700, Dan Magenheimer wrote:
> > real users and real distros and real products waiting, so if there
> > are any real issues, let's get them resolved.
>
> We already told you the real issues there are and you did nothing so
> far to address those, so much was built on top of a flawed API that I
> guess an heartquake of massive scale has to come in to actually
> convince Xen to change any of the huge amount of code built on the
> flawed API.
>
> I don't know the exact Xen details (it's possible Xen design doesn't
> allow these below 4 issues to be fixed, I've no idea) but for all
> other non-virt usages (compressed-swap/compressed-pagecache, ramster)
> I doubt it is impossible to change the design of the tmem API to
> address at least one of those basic huge troubles that such an API
> imposes:
Actually, I think there's an unexpressed fifth requirement:
5. The optimised use case should be for non-paging situations.
The problem here is that almost every data centre person tries very hard
to make sure their systems never tip into the swap zone. A lot of
hosting datacentres use tons of cgroup controllers for this and
deliberately never configure swap which makes transcendent memory
useless to them under the current API. I'm not sure this is fixable,
but it's the reason why a large swathe of users would never be
interested in the patches, because they by design never operate in the
region transcended memory is currently looking to address.
This isn't an inherent design flaw, but it does ask the question "is
your design scope too narrow?"
James
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next prev parent reply other threads:[~2011-11-01 10:16 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-27 18:52 [GIT PULL] mm: frontswap (for 3.2 window) Dan Magenheimer
[not found] ` <alpine.DEB.2.00.1110271318220.7639@chino.kir.corp.google.com20111027211157.GA1199@infradead.org>
2011-10-27 19:30 ` Kurt Hackel
2011-10-27 20:18 ` David Rientjes
2011-10-27 21:11 ` Christoph Hellwig
2011-10-27 21:49 ` Dan Magenheimer
2011-10-27 21:52 ` Christoph Hellwig
2011-10-27 22:21 ` Dan Magenheimer
2011-10-28 7:12 ` Sasha Levin
[not found] ` <CAOzbF4fnD=CGR-nizZoBxmFSuAjFC3uAHf3wDj5RLneJvJhrOQ@mail.gmail.comCAOJsxLGOTw7rtFnqeHvzFxifA0QgPVDHZzrEo=-uB2Gkrvp=JQ@mail.gmail.com>
[not found] ` <552d2067-474d-4aef-a9a4-89e5fd8ef84f@default20111031181651.GF3466@redhat.com>
[not found] ` <60592afd-97aa-4eaf-b86b-f6695d31c7f1@default20111031223717.GI3466@redhat.com>
[not found] ` <1b2e4f74-7058-4712-85a7-84198723e3ee@default20111101012017.GJ3466@redhat.com>
[not found] ` <6a9db6d9-6f13-4855-b026-ba668c29ddfa@default20111101180702.GL3466@redhat.com>
[not found] ` <b8a0ca71-a31b-488a-9a92-2502d4a6e9bf@default20111102013122.GA18879@redhat.com>
2011-10-28 7:30 ` Cyclonus J
2011-10-28 14:26 ` Pekka Enberg
2011-10-28 15:21 ` Dan Magenheimer
[not found] ` <CAOJsxLEE-qf9me1SAZLFiEVhHVnDh7BDrSx1+abe9R4mfkhD=g@mail.gmail.com20111028163053.GC1319@redhat.com>
2011-10-28 15:36 ` Pekka Enberg
2011-10-28 16:30 ` Johannes Weiner
2011-10-28 17:01 ` Pekka Enberg
2011-10-28 17:07 ` Dan Magenheimer
2011-10-28 18:28 ` John Stoffel
2011-10-28 20:19 ` Dan Magenheimer
2011-10-28 20:52 ` John Stoffel
2011-10-30 19:18 ` Dan Magenheimer
2011-10-30 20:06 ` Dave Hansen
2011-10-30 21:50 ` Dan Magenheimer
2011-11-02 19:45 ` Rik van Riel
2011-11-02 20:45 ` Dan Magenheimer
2011-11-06 22:32 ` Valdis.Kletnieks
2011-11-08 12:15 ` Ed Tomlinson
2011-10-31 8:12 ` James Bottomley
2011-10-31 15:39 ` Dan Magenheimer
2011-11-01 10:13 ` James Bottomley
2011-11-01 18:10 ` Dan Magenheimer
2011-11-01 18:48 ` Dave Hansen
2011-11-01 21:32 ` Dan Magenheimer
2011-11-02 7:44 ` James Bottomley
2011-11-02 19:39 ` Dan Magenheimer
2011-10-31 18:44 ` Andrea Arcangeli
2011-10-30 21:47 ` Johannes Weiner
2011-10-30 23:19 ` Dan Magenheimer
2011-10-31 18:34 ` Andrea Arcangeli
2011-10-31 21:45 ` Dan Magenheimer
2011-10-28 16:37 ` Dan Magenheimer
2011-10-28 16:59 ` Pekka Enberg
2011-10-28 17:20 ` Dan Magenheimer
2011-10-31 18:16 ` Andrea Arcangeli
2011-10-31 20:58 ` Dan Magenheimer
2011-10-31 22:37 ` Andrea Arcangeli
2011-10-31 23:36 ` Dan Magenheimer
2011-11-01 1:20 ` Andrea Arcangeli
2011-11-01 16:41 ` Dan Magenheimer
2011-11-01 18:07 ` Andrea Arcangeli
2011-11-01 21:00 ` Dan Magenheimer
2011-11-02 1:31 ` Andrea Arcangeli
2011-11-02 19:06 ` Dan Magenheimer
2011-11-03 0:32 ` Andrea Arcangeli
2011-11-03 22:29 ` Dan Magenheimer
2011-11-02 20:51 ` Rik van Riel
2011-11-02 21:14 ` Dan Magenheimer
2011-11-15 16:29 ` Rik van Riel
2011-11-15 17:33 ` Jeremy Fitzhardinge
2011-11-16 14:49 ` Konrad Rzeszutek Wilk
2011-11-01 10:16 ` James Bottomley [this message]
2011-11-01 18:21 ` Dan Magenheimer
2011-11-02 8:14 ` James Bottomley
2011-11-02 20:08 ` Dan Magenheimer
2011-11-03 10:30 ` Theodore Tso
2011-11-03 14:59 ` Dan Magenheimer
2011-11-02 15:44 ` Avi Kivity
2011-11-02 16:02 ` Andrea Arcangeli
2011-11-02 16:13 ` Avi Kivity
2011-11-02 20:27 ` Dan Magenheimer
2011-11-02 20:19 ` Dan Magenheimer
2011-10-27 21:44 ` Avi Miller
2011-10-27 22:33 ` Brian King
2011-10-28 5:17 ` Nitin Gupta
2011-10-29 13:43 ` Ed Tomlinson
2011-10-31 8:13 ` KAMEZAWA Hiroyuki
2011-10-31 16:38 ` Dan Magenheimer
2011-11-01 0:50 ` KAMEZAWA Hiroyuki
2011-11-01 15:25 ` Dan Magenheimer
2011-11-01 21:43 ` Andrew Morton
2011-11-01 22:25 ` Dan Magenheimer
2011-11-02 21:03 ` Rik van Riel
2011-11-02 21:42 ` Dan Magenheimer
2011-11-02 1:14 ` KAMEZAWA Hiroyuki
2011-11-02 15:12 ` Dan Magenheimer
2011-11-04 4:19 ` KAMEZAWA Hiroyuki
2011-11-03 16:49 ` Jan Beulich
2011-11-04 0:54 ` Andrew Morton
2011-11-04 8:49 ` Jan Beulich
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