[PATCH v2] enable all tmem backends to be built and loaded as modules.
From: Konrad Rzeszutek Wilk
Date: Wed Nov 14 2012 - 14:12:48 EST
There are also some patch I wrote up that are based on this patchset
that I will post soonish.
I copying here what Dan mentioned with some modifications by me:
Since various parts of transcendent memory ("tmem") [1] were first posted in
2009, reviewers have suggested that various tmem features should be built
as a module and enabled by loading the module, rather than the current clunky
method of compiling as a built-in and enabling via boot parameter. Due
to certain tmem initialization steps, that was not feasible at the time.
[1] http://lwn.net/Articles/454795/
This patchset allows each of the three merged transcendent memory
backends (zcache, ramster, Xen tmem) to be used as modules by first
enabling transcendent memory frontends (cleancache, frontswap) to deal
with "lazy initialization" and, second, by adding the necessary code for
the backends to be built and loaded as modules.
The original mechanism to enable tmem backends -- namely to hardwire
them into the kernel and select/enable one with a kernel boot
parameter -- is retained but should be considered deprecated. When
backends are loaded as modules, certain knobs will now be
properly selected via module_params rather than via undocumented
kernel boot parameters. Note that module UNloading is not yet
supported as it is lower priority and will require significant
additional work.
The lazy initialization support is necessary because filesystems
and swap devices are normally mounted early in boot and these
activites normally trigger tmem calls to setup certain data structures;
if the respective cleancache/frontswap ops are not yet registered
by a back end, the tmem setup would fail for these devices and
cleancache/frontswap would never be enabled for them which limits
much of the value of tmem in many system configurations. Lazy
initialization records the necessary information in cleancache/frontswap
data structures and "replays" it after the ops are registered
to ensure that all filesystems and swap devices can benefit from
the loaded tmem backend.
[PATCH 1/8] mm: cleancache: lazy initialization to allow tmem
[PATCH 2/8] mm: frontswap: lazy initialization to allow tmem
Patches 1 and 2 are the original [2] patches to cleancache and frontswap
proposed by Erlangen University, but rebased to 3.7-rcN plus a couple
of bug fixes I found necessary to run properly + extra review comments.
[2] http://www.spinics.net/lists/linux-mm/msg31490.html
The other two:
[PATCH 3/8] frontswap: Make frontswap_init use a pointer for the
[PATCH 4/8] cleancache: Make cleancache_init use a pointer for the
do a bit of code cleanup that can be done to make it easier to
read and also remove some of the bools.
[PATCH 5/8] staging: zcache2+ramster: enable ramster to be
Enables module support for zcache2. Zsmalloc support
has not yet been merged into zcache2 but, once merged, could now
easily be selected via a module_param.
[PATCH 6/8] staging: zcache2+ramster: enable zcache2 to be
Enables module support for ramster. Ramster will now be
enabled with a module_param to zcache2.
[PATCH 7/8] xen: tmem: enable Xen tmem shim to be built/loaded as a
[PATCH 8/8] xen/tmem: Remove the subsys call.
Enables module support for the Xen tmem shim. Xen self-ballooning and
frontswap-selfshrinking are also "lazily"
initialized when the Xen tmem shim is loaded as a module, unless
explicitly disabled by module_params.
Dan Magenheimer (5):
mm: cleancache: lazy initialization to allow tmem backends to build/run as modules
mm: frontswap: lazy initialization to allow tmem backends to build/run as modules
staging: zcache2+ramster: enable ramster to be built/loaded as a module
staging: zcache2+ramster: enable zcache2 to be built/loaded as a module
xen: tmem: enable Xen tmem shim to be built/loaded as a module
Konrad Rzeszutek Wilk (3):
frontswap: Make frontswap_init use a pointer for the ops.
cleancache: Make cleancache_init use a pointer for the ops
xen/tmem: Remove the subsys call.
drivers/staging/ramster/Kconfig | 6 +-
drivers/staging/ramster/Makefile | 11 +-
drivers/staging/ramster/ramster.h | 6 +-
drivers/staging/ramster/ramster/nodemanager.c | 9 +-
drivers/staging/ramster/ramster/ramster.c | 29 +++-
drivers/staging/ramster/ramster/ramster.h | 2 +-
.../staging/ramster/ramster/ramster_nodemanager.h | 2 +
drivers/staging/ramster/tmem.c | 6 +-
drivers/staging/ramster/tmem.h | 8 +-
drivers/staging/ramster/zcache-main.c | 63 ++++++--
drivers/staging/ramster/zcache.h | 2 +-
drivers/staging/zcache/zcache-main.c | 16 +-
drivers/xen/Kconfig | 4 +-
drivers/xen/tmem.c | 50 ++++--
drivers/xen/xen-selfballoon.c | 13 +-
include/linux/cleancache.h | 2 +-
include/linux/frontswap.h | 2 +-
include/xen/tmem.h | 8 +
mm/cleancache.c | 167 +++++++++++++++++---
mm/frontswap.c | 78 +++++++--
20 files changed, 371 insertions(+), 113 deletions(-)
>From Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> # This line is ignored.
Subject: [PATCH v2] enable all tmem backends to be built and loaded as modules.
Changelog since [v1: https://lkml.org/lkml/2012/10/31/403]
- Addressed various people comments (most of them in the frontswap code).
- Fixed up compile issues.
There are also some patch I wrote up that are based on this patchset
that I will post soonish.
I copying here what Dan mentioned with some modifications by me:
Since various parts of transcendent memory ("tmem") [1] were first posted in
2009, reviewers have suggested that various tmem features should be built
as a module and enabled by loading the module, rather than the current clunky
method of compiling as a built-in and enabling via boot parameter. Due
to certain tmem initialization steps, that was not feasible at the time.
[1] http://lwn.net/Articles/454795/
This patchset allows each of the three merged transcendent memory
backends (zcache, ramster, Xen tmem) to be used as modules by first
enabling transcendent memory frontends (cleancache, frontswap) to deal
with "lazy initialization" and, second, by adding the necessary code for
the backends to be built and loaded as modules.
The original mechanism to enable tmem backends -- namely to hardwire
them into the kernel and select/enable one with a kernel boot
parameter -- is retained but should be considered deprecated. When
backends are loaded as modules, certain knobs will now be
properly selected via module_params rather than via undocumented
kernel boot parameters. Note that module UNloading is not yet
supported as it is lower priority and will require significant
additional work.
The lazy initialization support is necessary because filesystems
and swap devices are normally mounted early in boot and these
activites normally trigger tmem calls to setup certain data structures;
if the respective cleancache/frontswap ops are not yet registered
by a back end, the tmem setup would fail for these devices and
cleancache/frontswap would never be enabled for them which limits
much of the value of tmem in many system configurations. Lazy
initialization records the necessary information in cleancache/frontswap
data structures and "replays" it after the ops are registered
to ensure that all filesystems and swap devices can benefit from
the loaded tmem backend.
[PATCH 1/8] mm: cleancache: lazy initialization to allow tmem
[PATCH 2/8] mm: frontswap: lazy initialization to allow tmem
Patches 1 and 2 are the original [2] patches to cleancache and frontswap
proposed by Erlangen University, but rebased to 3.7-rcN plus a couple
of bug fixes I found necessary to run properly + extra review comments.
[2] http://www.spinics.net/lists/linux-mm/msg31490.html
The other two:
[PATCH 3/8] frontswap: Make frontswap_init use a pointer for the
[PATCH 4/8] cleancache: Make cleancache_init use a pointer for the
do a bit of code cleanup that can be done to make it easier to
read and also remove some of the bools.
[PATCH 5/8] staging: zcache2+ramster: enable ramster to be
Enables module support for zcache2. Zsmalloc support
has not yet been merged into zcache2 but, once merged, could now
easily be selected via a module_param.
[PATCH 6/8] staging: zcache2+ramster: enable zcache2 to be
Enables module support for ramster. Ramster will now be
enabled with a module_param to zcache2.
[PATCH 7/8] xen: tmem: enable Xen tmem shim to be built/loaded as a
[PATCH 8/8] xen/tmem: Remove the subsys call.
Enables module support for the Xen tmem shim. Xen self-ballooning and
frontswap-selfshrinking are also "lazily"
initialized when the Xen tmem shim is loaded as a module, unless
explicitly disabled by module_params.
Dan Magenheimer (5):
mm: cleancache: lazy initialization to allow tmem backends to build/run as modules
mm: frontswap: lazy initialization to allow tmem backends to build/run as modules
staging: zcache2+ramster: enable ramster to be built/loaded as a module
staging: zcache2+ramster: enable zcache2 to be built/loaded as a module
xen: tmem: enable Xen tmem shim to be built/loaded as a module
Konrad Rzeszutek Wilk (3):
frontswap: Make frontswap_init use a pointer for the ops.
cleancache: Make cleancache_init use a pointer for the ops
xen/tmem: Remove the subsys call.
drivers/staging/ramster/Kconfig | 6 +-
drivers/staging/ramster/Makefile | 11 +-
drivers/staging/ramster/ramster.h | 6 +-
drivers/staging/ramster/ramster/nodemanager.c | 9 +-
drivers/staging/ramster/ramster/ramster.c | 29 +++-
drivers/staging/ramster/ramster/ramster.h | 2 +-
.../staging/ramster/ramster/ramster_nodemanager.h | 2 +
drivers/staging/ramster/tmem.c | 6 +-
drivers/staging/ramster/tmem.h | 8 +-
drivers/staging/ramster/zcache-main.c | 63 ++++++--
drivers/staging/ramster/zcache.h | 2 +-
drivers/staging/zcache/zcache-main.c | 16 +-
drivers/xen/Kconfig | 4 +-
drivers/xen/tmem.c | 50 ++++--
drivers/xen/xen-selfballoon.c | 13 +-
include/linux/cleancache.h | 2 +-
include/linux/frontswap.h | 2 +-
include/xen/tmem.h | 8 +
mm/cleancache.c | 167 +++++++++++++++++---
mm/frontswap.c | 78 +++++++--
20 files changed, 371 insertions(+), 113 deletions(-)
>From Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> # This line is ignored.
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Subject: [PATCH] zcache2 cleanups (s/int/bool/ + debugfs move).
In-Reply-To:
Changelog since rfc: https://lkml.org/lkml/2012/11/5/549
- Added Reviewed-by from Dan.
This patchset depends on the recently posted V2 of making the
frontswap/cleancache backends be module capable:
http://mid.gmane.org/1352919432-9699-1-git-send-email-konrad.wilk@xxxxxxxxxx
I think that once the V2 is OK I will combine this patchset along
with the V2 and send the whole thing to GregKH? Or perhaps just
if Greg is Ok I will do via my tree.
This is a copy of what I wrote in the RFC posting:
Looking at the zcache2 code there were a couple of things that I thought
would make sense to move out of the code. For one thing it makes it easier
to read, and for anoter - it can be cleanly compiled out. It also allows
to have a clean seperation of counters that we _need_ vs the optional ones.
Which means that in the future we could get rid of the optional ones.
It fixes some outstanding compile warnings, cleans
up some of the code, and rips out the debug counters out of zcache-main.c
and sticks them in a debug.c file.
I was hoping it would end up with less code, but sadly it ended up with
a bit more due to the empty non-debug functions - but the code is easier
to read.
drivers/staging/ramster/Kconfig | 8 +
drivers/staging/ramster/Makefile | 1 +
drivers/staging/ramster/debug.c | 66 +++++++
drivers/staging/ramster/debug.h | 229 ++++++++++++++++++++++
drivers/staging/ramster/zcache-main.c | 336 +++++++--------------------------
5 files changed, 370 insertions(+), 270 deletions(-)
Konrad Rzeszutek Wilk (11):
zcache: Provide accessory functions for counter increase
zcache: Provide accessory functions for counter decrease.
zcache: The last of the atomic reads has now an accessory function.
zcache: Fix compile warnings due to usage of debugfs_create_size_t
zcache: Make the debug code use pr_debug
zcache: Move debugfs code out of zcache-main.c file.
zcache: Use an array to initialize/use debugfs attributes.
zcache: Move the last of the debugfs counters out
zcache: Allow to compile if ZCACHE_DEBUG and !DEBUG_FS
zcache: Module license is defined twice.
zcache: Coalesce all debug under CONFIG_ZCACHE2_DEBUG
>From Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> # This line is ignored.
Subject: [PATCH] zcache2 cleanups (s/int/bool/ + debugfs move).
Changelog since rfc: https://lkml.org/lkml/2012/11/5/549
- Added Reviewed-by from Dan.
This patchset depends on the recently posted V2 of making the
frontswap/cleancache backends be module capable:
http://mid.gmane.org/1352919432-9699-1-git-send-email-konrad.wilk@xxxxxxxxxx
I think that once the V2 is OK I will combine this patchset along
with the V2 and send the whole thing to GregKH? Or perhaps just
if Greg is Ok I will do via my tree.
This is a copy of what I wrote in the RFC posting:
Looking at the zcache2 code there were a couple of things that I thought
would make sense to move out of the code. For one thing it makes it easier
to read, and for anoter - it can be cleanly compiled out. It also allows
to have a clean seperation of counters that we _need_ vs the optional ones.
Which means that in the future we could get rid of the optional ones.
It fixes some outstanding compile warnings, cleans
up some of the code, and rips out the debug counters out of zcache-main.c
and sticks them in a debug.c file.
I was hoping it would end up with less code, but sadly it ended up with
a bit more due to the empty non-debug functions - but the code is easier
to read.
drivers/staging/ramster/Kconfig | 8 +
drivers/staging/ramster/Makefile | 1 +
drivers/staging/ramster/debug.c | 66 +++++++
drivers/staging/ramster/debug.h | 229 ++++++++++++++++++++++
drivers/staging/ramster/zcache-main.c | 336 +++++++--------------------------
5 files changed, 370 insertions(+), 270 deletions(-)
Konrad Rzeszutek Wilk (11):
zcache: Provide accessory functions for counter increase
zcache: Provide accessory functions for counter decrease.
zcache: The last of the atomic reads has now an accessory function.
zcache: Fix compile warnings due to usage of debugfs_create_size_t
zcache: Make the debug code use pr_debug
zcache: Move debugfs code out of zcache-main.c file.
zcache: Use an array to initialize/use debugfs attributes.
zcache: Move the last of the debugfs counters out
zcache: Allow to compile if ZCACHE_DEBUG and !DEBUG_FS
zcache: Module license is defined twice.
zcache: Coalesce all debug under CONFIG_ZCACHE2_DEBUG
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