Re: [GIT PULL] mm: frontswap (for 3.2 window)

[Kurt Hackel]

Hi,
As the dev manager for OracleVM (x86) I'd like to express my interest in seeing frontswap get merged upstream.  The OracleVM product has been capable of working with frontswap for over a year now, and we'd very much like to see the complete cleancache+frontswap feature set fully upstreamed.  Oracle is also fully committed to the ongoing maintenance of frontswap.
thanks
kurt

Kurt C. Hackel
Development Director
Oracle VM
kurt.hackel@xxxxxxxxxx


On 10/27/2011 11:52 AM, Dan Magenheimer wrote:
> Hi Linus --
>
> Frontswap now has FOUR users: Two already merged in-tree (zcache
> and Xen) and two still in development but in public git trees
> (RAMster and KVM).  Frontswap is part 2 of 2 of the core kernel
> changes required to support transcendent memory; part 1 was cleancache
> which you merged at 3.0 (and which now has FIVE users).
>
> Frontswap patches have been in linux-next since June 3 (with zero
> changes since Sep 22).  First posted to lkml in June 2009, frontswap
> is now at version 11 and has incorporated feedback from a wide range
> of kernel developers.  For a good overview, see
>     http://lwn.net/Articles/454795.
> If further rationale is needed, please see the end of this email
> for more info.
>
> SO... Please pull:
>
> git://oss.oracle.com/git/djm/tmem.git #tmem
>
> since git commit b6fd41e29dea9c6753b1843a77e50433e6123bcb
> Linus Torvalds (1):
>
> 	Linux 3.1-rc6
>
> (identical commits being pulled by sfr into linux-next since Sep22)
>
> Note that in addition to frontswap, this commit series includes
> some minor changes to cleancache necessary for consistency with
> changes for frontswap required by Andrew Morton (e.g. flush->invalidate
> name change; use debugfs instead of sysfs).  As a result, a handful
> of cleancache-related VFS files incur only a very small change.
>
> Dan Magenheimer (8):
>        mm: frontswap: add frontswap header file
>        mm: frontswap: core swap subsystem hooks and headers
>        mm: frontswap: core frontswap functionality
>        mm: frontswap: config and doc files
>        mm: cleancache: s/flush/invalidate/
>        mm: frontswap/cleancache: s/flush/invalidate/
>        mm: cleancache: report statistics via debugfs instead of sysfs.
>        mm: cleancache: Use __read_mostly as appropiate.
>
> Diffstat:
>   .../ABI/testing/sysfs-kernel-mm-cleancache         |   11 -
>   Documentation/vm/cleancache.txt                    |   41 ++--
>   Documentation/vm/frontswap.txt                     |  210 +++++++++++++++
>   drivers/staging/zcache/zcache-main.c               |   10 +-
>   drivers/xen/tmem.c                                 |   10 +-
>   fs/buffer.c                                        |    2 +-
>   fs/super.c                                         |    2 +-
>   include/linux/cleancache.h                         |   24 +-
>   include/linux/frontswap.h                          |    9 +-
>   include/linux/swap.h                               |    4 +
>   include/linux/swapfile.h                           |   13 +
>   mm/Kconfig                                         |   17 ++
>   mm/Makefile                                        |    1 +
>   mm/cleancache.c                                    |   98 +++-----
>   mm/filemap.c                                       |    2 +-
>   mm/frontswap.c                                     |  273 ++++++++++++++++++++
>   mm/page_io.c                                       |   12 +
>   mm/swapfile.c                                      |   64 ++++-
>   mm/truncate.c                                      |   10 +-
>   19 files changed, 672 insertions(+), 141 deletions(-)
>
> ====
>
> FURTHER RATIONALE, INFORMATION, AND LINKS:
>
> In-kernel users (grep for CONFIG_FRONTSWAP):
> - drivers/staging/zcache (since 2.6.39)
> - drivers/xen/tmem.c (since 3.1)
> - drivers/xen/xen-selfballoon.c (since 3.1)
>
> Users in development in public git trees:
> - "RAMster" driver, see ramster branch of
>      git://oss.oracle.com/git/djm/tmem.git
> - KVM port now underway, see:
>      https://github.com/sashalevin/kvm-tmem/commits/tmem
>
> History of frontswap code:
> - code first written in Dec 2008
> - previously known as "hswap" and "preswap"
> - first public posting in Feb 2009
> - first LKML posting on June 19, 2009
> - renamed frontswap, posted on May 28, 2010
> - in linux-next since June 3, 2011
> - incorporated feedback from: (partial list)
>     Andrew Morton, Jan Beulich, Konrad Wilk,
>      Jeremy Fitzhardinge, Kamezawa Hiroyuki,
>      Seth Jennings (IBM)
>
> Linux kernel distros incorporating frontswap:
> - Oracle UEK 2.6.39 Beta:
>     http://oss.oracle.com/git/?p=linux-2.6-unbreakable-beta.git;a=summary
> - OpenSuSE since 11.2 (2009) [see mm/tmem-xen.c]
>     http://kernel.opensuse.org/cgit/kernel/
> - a popular Gentoo distro
>     http://forums.gentoo.org/viewtopic-t-862105.html
>
> Xen distros supporting Linux guests with frontswap:
> - Xen hypervisor backend since Xen 4.0 (2009)
>     http://www.xen.org/files/Xen_4_0_Datasheet.pdf
> - OracleVM since 2.2 (2009)
>     http://twitter.com/#!/Djelibeybi/status/113876514688352256
>
> Public visibility for frontswap (as part of transcendent memory):
> - presented at OSDI'08, OLS'09, LCA'10, LPC'10, LinuxCon NA 11, Oracle
>    Open World 2011, two LSF/MM Summits (2010,2011), and three
>    Xen Summits (2009,2010,2011)
> - http://lwn.net/Articles/454795 (current overview)
> - http://lwn.net/Articles/386090 (2010)
> - http://lwn.net/Articles/340080 (2009)
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