From: David Singleton <David.Singleton@anu.edu.au>
To: Caitlin Bestler <caitlin.bestler@gmail.com>
Cc: Steve Wise <swise@opengridcomputing.com>,
Robin Holt <holt@sgi.com>, Rik van Riel <riel@redhat.com>,
steiner@sgi.com, a.p.zijlstra@chello.nl,
Roland Dreier <rdreier@cisco.com>,
linux-mm@kvack.org, daniel.blueman@quadrics.com,
general@lists.openfabrics.org,
Christoph Lameter <clameter@sgi.com>,
pw@osc.edu
Subject: Re: [ofa-general] Re: Demand paging for memory regions
Date: Fri, 15 Feb 2008 07:47:06 +1100 [thread overview]
Message-ID: <47B4A8CA.30306@anu.edu.au> (raw)
In-Reply-To: <469958e00802140948j162cc8baqae0b55cd6fb1cd22@mail.gmail.com>
Caitlin Bestler wrote:
>
> But the broader question is what the goal is here. Allowing memory to
> be shuffled is valuable, and perhaps even ultimately a requirement for
> high availability systems. RDMA and other direct-access APIs should
> be evolving their interfaces to accommodate these needs.
>
> Oversubscribing memory is a totally different matter. If an application
> is working with memory that is oversubscribed by a factor of 2 or more
> can it really benefit from zero-copy direct placement? At first glance I
> can't see what RDMA could be bringing of value when the overhead of
> swapping is going to be that large.
>
A related use case from HPC. Some of us have batch scheduling
systems based on suspend/resume of jobs (which is really just
SIGSTOP and SIGCONT of all job processes). The value of this
system is enhanced greatly by being able to page out the suspended
job (just normal Linux demand paging caused by the incoming job is
OK). Apart from this (relatively) brief period of paging, both
jobs benefit from RDMA.
SGI kindly implemented a /proc mechanism for unpinning of XPMEM
pages to allow suspended jobs to be paged on their Altix system.
Note that this use case would not benefit from Pete Wyckoff's
approach of notifying user applications/libraries of VM changes.
And one of the grand goal of HPC developers has always been to have
checkpoint/restart of jobs ....
David
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next prev parent reply other threads:[~2008-02-14 20:47 UTC|newest]
Thread overview: 84+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-08 22:06 [patch 0/6] MMU Notifiers V6 Christoph Lameter
2008-02-08 22:06 ` [patch 1/6] mmu_notifier: Core code Christoph Lameter
2008-02-08 22:06 ` [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges Christoph Lameter
2008-02-08 22:06 ` [patch 3/6] mmu_notifier: invalidate_page callbacks Christoph Lameter
2008-02-08 22:06 ` [patch 4/6] mmu_notifier: Skeleton driver for a simple mmu_notifier Christoph Lameter
2008-02-08 22:06 ` [patch 5/6] mmu_notifier: Support for drivers with revers maps (f.e. for XPmem) Christoph Lameter
2008-02-08 22:06 ` [patch 6/6] mmu_rmap_notifier: Skeleton for complex driver that uses its own rmaps Christoph Lameter
2008-02-08 22:23 ` [patch 0/6] MMU Notifiers V6 Andrew Morton
2008-02-08 23:32 ` Christoph Lameter
2008-02-08 23:36 ` Robin Holt
2008-02-08 23:41 ` Christoph Lameter
2008-02-08 23:43 ` Robin Holt
2008-02-08 23:56 ` Andrew Morton
2008-02-09 0:05 ` Christoph Lameter
2008-02-09 0:12 ` [ofa-general] " Roland Dreier
2008-02-09 0:16 ` Christoph Lameter
2008-02-09 0:21 ` [ofa-general] trying to get of all lists R S
2008-02-09 0:22 ` [ofa-general] Re: [patch 0/6] MMU Notifiers V6 Roland Dreier
2008-02-09 0:36 ` Christoph Lameter
2008-02-09 1:24 ` Andrea Arcangeli
2008-02-09 1:27 ` Christoph Lameter
2008-02-09 1:56 ` Andrea Arcangeli
2008-02-09 2:16 ` Christoph Lameter
2008-02-09 12:55 ` Rik van Riel
2008-02-09 21:46 ` Christoph Lameter
2008-02-11 22:40 ` Demand paging for memory regions (was Re: MMU Notifiers V6) Roland Dreier
2008-02-12 22:01 ` Steve Wise
2008-02-12 22:10 ` Christoph Lameter
2008-02-12 22:41 ` [ofa-general] Re: Demand paging for memory regions Roland Dreier
2008-02-12 23:14 ` Felix Marti
2008-02-13 0:57 ` Christoph Lameter
2008-02-14 15:09 ` Steve Wise
2008-02-14 15:53 ` Robin Holt
2008-02-14 16:23 ` Steve Wise
2008-02-14 17:48 ` Caitlin Bestler
2008-02-14 20:47 ` David Singleton [this message]
2008-02-15 9:55 ` Robin Holt
2008-02-14 19:39 ` Christoph Lameter
2008-02-14 20:17 ` Caitlin Bestler
2008-02-14 20:20 ` Christoph Lameter
2008-02-14 22:43 ` Caitlin Bestler
2008-02-14 22:48 ` Christoph Lameter
2008-02-15 1:26 ` Caitlin Bestler
2008-02-15 2:37 ` Christoph Lameter
2008-02-15 18:09 ` Caitlin Bestler
2008-02-15 18:45 ` Christoph Lameter
2008-02-15 18:53 ` Caitlin Bestler
2008-02-15 20:02 ` Christoph Lameter
2008-02-15 20:14 ` Caitlin Bestler
2008-02-15 22:50 ` Christoph Lameter
2008-02-15 23:50 ` Caitlin Bestler
2008-02-12 23:23 ` Jason Gunthorpe
2008-02-13 1:01 ` Christoph Lameter
2008-02-13 1:26 ` Jason Gunthorpe
2008-02-13 1:45 ` Steve Wise
2008-02-13 2:35 ` Christoph Lameter
2008-02-13 3:25 ` Jason Gunthorpe
2008-02-13 3:56 ` Patrick Geoffray
2008-02-13 4:26 ` Jason Gunthorpe
2008-02-13 4:47 ` Patrick Geoffray
2008-02-13 18:51 ` Christoph Lameter
2008-02-13 19:51 ` Jason Gunthorpe
2008-02-13 20:36 ` Christoph Lameter
2008-02-13 4:09 ` Christian Bell
2008-02-13 19:00 ` Christoph Lameter
2008-02-13 19:46 ` Christian Bell
2008-02-13 20:32 ` Christoph Lameter
2008-02-13 22:44 ` Kanoj Sarcar
2008-02-13 23:02 ` Christoph Lameter
2008-02-13 23:43 ` Kanoj Sarcar
2008-02-13 23:48 ` Jesse Barnes
2008-02-14 0:56 ` [ofa-general] " Andrea Arcangeli
2008-02-14 19:35 ` Christoph Lameter
2008-02-13 23:23 ` Pete Wyckoff
2008-02-14 0:01 ` Jason Gunthorpe
2008-02-27 22:11 ` Christoph Lameter
2008-02-13 1:55 ` Christian Bell
2008-02-13 2:19 ` Christoph Lameter
2008-02-13 0:56 ` Christoph Lameter
2008-02-13 12:11 ` Christoph Raisch
2008-02-13 19:02 ` Christoph Lameter
2008-02-09 0:12 ` [patch 0/6] MMU Notifiers V6 Andrew Morton
2008-02-09 0:18 ` Christoph Lameter
2008-02-13 14:31 ` Jack Steiner
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