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From: Bill Jordan <woodennickel@gmail.com>
To: Roland Dreier <roland@topspin.com>
Cc: Caitlin Bestler <caitlin.bestler@gmail.com>,
	Andrew Morton <akpm@osdl.org>,
	hch@infradead.org, linux-kernel@vger.kernel.org,
	openib-general@openib.org, Timur Tabi <timur.tabi@ammasso.com>
Subject: Re: RDMA memory registration (was: [openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation)
Date: Fri, 29 Apr 2005 15:43:10 -0400	[thread overview]
Message-ID: <5ebee0d1050429124333776354@mail.gmail.com> (raw)
In-Reply-To: <52d5sdjzup.fsf_-_@topspin.com>

On 4/29/05, Roland Dreier <roland@topspin.com> wrote:
>   b) (maybe someday?) Add a VM_ALWAYSCOPY flag and extend mprotect()
>      with PROT_ALWAYSCOPY so processes can mark pages to be
>      pre-copied into child processes, to handle the case where only
>      half a page is registered.

Are you suggesting making the partial pages their own VMA, or marking
the entire buffer with this flag? I originally thought the entire
buffer should be copy on fork (instead of copy on write), and I
believe this is the path Mellanox was pursing with the VM_NO_COW flag.
However, if applications are registering gigs of ram, it would be very
bad to have the entire area copied on fork.

On the other hand, I've always wondered about the choice to leave
holes in the child process's address space. I would have chosen to map
the zero page instead.

-- 
Bill Jordan
InfiniCon Systems

  parent reply	other threads:[~2005-04-29 19:43 UTC|newest]

Thread overview: 143+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-04-04 22:09 [PATCH][RFC][0/4] InfiniBand userspace verbs implementation Roland Dreier
2005-04-04 22:09 ` [PATCH][RFC][1/4] IB: core changes for userspace verbs Roland Dreier
2005-04-04 22:09   ` [PATCH][RFC][2/4] IB: userspace verbs main module Roland Dreier
2005-04-04 22:09     ` [PATCH][RFC][3/4] IB: userspace verbs mthca changes Roland Dreier
2005-04-04 22:09       ` [PATCH][RFC][4/4] IB: userspace verbs Kconfig/Makefile changes Roland Dreier
2005-04-04 22:49       ` [openib-general] [PATCH][RFC][3/4] IB: userspace verbs mthca changes Tom Duffy
2005-04-04 23:34         ` Roland Dreier
2005-04-21  0:37       ` [PATCH][MTHCA] fix sparc build WAS: " Tom Duffy
2005-04-21  0:38         ` David S. Miller
2005-04-11 14:22 ` [PATCH][RFC][0/4] InfiniBand userspace verbs implementation Troy Benjegerdes
2005-04-11 15:34   ` Roland Dreier
2005-04-11 16:33     ` Troy Benjegerdes
2005-04-11 16:56       ` Roland Dreier
2005-04-11 18:01         ` Troy Benjegerdes
2005-04-11 18:03           ` Roland Dreier
2005-04-12  0:13             ` Andrew Morton
2005-04-12  0:21               ` Roland Dreier
2005-04-12 18:23                 ` Michael S. Tsirkin
2005-04-13 18:28                   ` Roland Dreier
2005-04-13 19:32                     ` Andrew Morton
2005-04-13  1:04               ` [openib-general] " Libor Michalek
2005-04-18 17:15                 ` Timur Tabi
2005-04-26  3:31                 ` Libor Michalek
2005-05-04 18:27                   ` Timur Tabi
2005-05-05 18:48                     ` Timur Tabi
2005-05-06 23:08                       ` Timur Tabi
2005-05-07 13:18                         ` Hugh Dickins
2005-05-07 14:45                           ` Timur Tabi
2005-05-07 16:30                             ` Hugh Dickins
2005-05-11 20:12                               ` William Jordan
2005-05-11 20:42                                 ` Hugh Dickins
2005-05-11 22:52                                   ` Andrea Arcangeli
2005-05-11 22:49                                 ` Andrea Arcangeli
2005-05-11 22:53                                   ` Timur Tabi
2005-05-11 23:05                                     ` Andrea Arcangeli
2005-05-05 23:34                     ` Libor Michalek
2005-04-18 16:22               ` Timur Tabi
2005-04-18 16:43                 ` Christoph Hellwig
2005-04-18 16:45                   ` Timur Tabi
2005-04-24  2:44                     ` Andrew Morton
2005-04-24 14:23                       ` Timur Tabi
2005-04-24 20:53                         ` Greg KH
2005-04-24 21:52                           ` Timur Tabi
2005-04-25  1:03                             ` Greg KH
2005-04-25  4:12                               ` Timur Tabi
2005-04-25 13:30                                 ` Dave Hansen
2005-04-25 13:15                         ` Roland Dreier
2005-04-25 13:17                           ` Christoph Hellwig
2005-04-25 14:16                             ` Roland Dreier
2005-04-25 20:54                           ` Andrew Morton
2005-04-25 21:12                             ` Roland Dreier
2005-04-25 22:14                               ` Andrew Morton
2005-04-25 22:21                                 ` Timur Tabi
2005-04-25 22:32                                   ` Andrew Morton
2005-04-25 23:58                                     ` Roland Dreier
2005-04-26  0:11                                       ` Andrew Morton
2005-04-26  0:23                                         ` Roland Dreier
2005-04-26  0:37                                           ` Andrew Morton
2005-04-26  2:21                                             ` Timur Tabi
2005-04-26  3:16                                               ` Andrew Morton
2005-04-26  3:38                                                 ` Timur Tabi
2005-04-26  4:33                                                   ` Andrew Morton
2005-04-26 14:07                                                     ` Timur Tabi
2005-04-26 15:31                                             ` Roland Dreier
2005-04-26 15:42                                               ` [openib-general] " Libor Michalek
2005-04-26 15:49                                                 ` Roland Dreier
2005-04-26 19:28                                                   ` Andrew Morton
2005-04-26 20:14                                                     ` Roland Dreier
2005-04-26 20:18                                                       ` Timur Tabi
2005-04-26 20:37                                                         ` Andrew Morton
2005-04-29 14:26                                                           ` Bill Jordan
2005-04-29 15:56                                                             ` Caitlin Bestler
2005-04-29 16:45                                                               ` RDMA memory registration (was: [openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation) Roland Dreier
2005-04-29 17:23                                                                 ` Libor Michalek
2005-04-29 18:22                                                                 ` RDMA memory registration Brice Goglin
2005-04-29 18:31                                                                   ` Roland Dreier
2005-04-29 19:33                                                                   ` [openib-general] " Grant Grundler
2005-05-03  8:42                                                                     ` David Addison
2005-05-03 15:36                                                                       ` Grant Grundler
2005-04-29 19:43                                                                 ` Bill Jordan [this message]
2005-04-29 19:45                                                                   ` Roland Dreier
2005-04-29 17:04                                                               ` [openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation Libor Michalek
2005-04-30  0:31                                                                 ` Caitlin Bestler
2005-05-03 18:43                                                                   ` Andy Isaacson
2005-05-03 19:04                                                                     ` Caitlin Bestler
2005-05-04 18:22                                                                     ` William Jordan
2005-05-05  1:27                                                                       ` Rik van Riel
2005-05-05  1:57                                                                         ` Andy Isaacson
2005-04-26 20:32                                                       ` Andrew Morton
2005-04-26 21:23                                                         ` Roland Dreier
2005-04-27  0:05                                                           ` Andrew Morton
2005-04-27  2:13                                                             ` Roland Dreier
2005-04-27  3:21                                                             ` Caitlin Bestler
2005-04-27  3:15                                                     ` Caitlin Bestler
2005-04-26  2:03                                       ` IWAMOTO Toshihiro
2005-04-26  2:16                                         ` Timur Tabi
2005-04-26  2:26                                         ` [openib-general] " Stephen Langdon
2005-04-25 22:23                                 ` Timur Tabi
2005-04-25 22:35                                   ` Andrew Morton
2005-04-25 22:42                                     ` Timur Tabi
2005-04-25 23:13                                       ` Andrew Morton
2005-04-25 23:21                                         ` Timur Tabi
2005-04-25 23:27                                           ` Andrew Morton
2005-04-26  0:08                                         ` Roland Dreier
2005-04-25 22:51                                     ` [openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace verbsimplementation Bob Woodruff
2005-04-25 23:13                                       ` Timur Tabi
2005-04-25 23:17                                         ` Andrew Morton
2005-04-25 23:29                                         ` Bob Woodruff
2005-04-25 23:17                                     ` [openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation Libor Michalek
2005-04-25 23:24                                       ` Andrew Morton
2005-04-25 23:37                                         ` Caitlin Bestler
2005-04-26  0:10                                           ` Andrew Morton
2005-04-26  3:55                                         ` Libor Michalek
2005-04-26  0:02                                 ` Roland Dreier
2005-04-26  6:12                                   ` Christoph Hellwig
2005-04-26 13:45                                     ` [openib-general] " Caitlin Bestler
2005-04-26 15:24                                     ` Timur Tabi
2005-04-25 19:11                       ` Andy Isaacson
2005-04-18 16:09     ` Timur Tabi
2005-04-18 16:12       ` Roland Dreier
2005-04-18 16:50         ` Timur Tabi
2005-04-21 19:47           ` Pavel Machek
2005-04-18 16:16       ` Arjan van de Ven
2005-04-18 16:25         ` Timur Tabi
2005-04-18 19:40           ` Arjan van de Ven
2005-04-18 20:00             ` Timur Tabi
2005-04-18 20:05               ` Arjan van de Ven
2005-04-18 20:19                 ` Timur Tabi
2005-04-18 20:07             ` [openib-general] " Bernhard Fischer
2005-04-21  2:17               ` Troy Benjegerdes
2005-04-21  3:07                 ` Timur Tabi
2005-04-21 17:38                   ` Andy Isaacson
2005-04-21 18:39                     ` Timur Tabi
2005-04-21 19:56                       ` Andy Isaacson
2005-04-21 20:07                         ` Timur Tabi
2005-04-21 20:12                           ` Chris Wright
2005-04-21 20:14                             ` Timur Tabi
2005-04-21 20:25                               ` Chris Wright
2005-04-21 20:30                                 ` Arjan van de Ven
2005-04-22  6:14                           ` Greg KH
2005-04-22 17:55         ` Timur Tabi
2005-04-22 18:12           ` Arjan van de Ven
2005-04-29  0:56         ` Andrew Morton

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