mm: frontswap: add frontswap header file
Frontswap is the alter ego of cleancache, the "yang" to cleancache's
"yin"... and more precisely frontswap is the provider of anonymous
pages to transcendent memory to nicely complement cleancache's providing
of clean pagecache pages to transcendent memory. For optimal use
of transcendent memory, both are necessary... because a kernel
under memory pressure first reclaims clean pagecache pages and,
when under more memory pressure, starts swapping anonymous pages.
Frontswap and cleancache (which was merged at 3.0) are the "frontends"
and the only necessary changes to the core kernel for transcendent memory;
all other supporting code -- the "backends" -- is implemented as drivers.
See the LWN.net article "Transcendent memory in a nutshell" for a detailed
overview of frontswap and related kernel parts:
https://lwn.net/Articles/454795/
Frontswap code was first posted publicly in January 2009 and on LKML in
May 2009, and has remained functionally stable for nearly three years now.
It is barely invasive, touching only the swap subsystem and adds less
than 100 lines of code to existing swap subsystem code files.
It has improved syntactically substantially between V1 and this posting
of V14, thanks to the review of a few kernel developers, and has adapted
easily to at least one major swap subsystem change. As of 3.4, there are
three in-tree users of frontswap patiently waiting for this patchset and
for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at
2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver
merged at 3.4). In addition, a RFC has been posted for a KVM backend.
The frontswap patchset has been in linux-next since next-110603. Earlier
versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel
and SuSE SLES.
This patch, 1of4, provides the header file for the core code for frontswap
that interfaces between the hooks in the swap subsystem and a frontswap
backend via frontswap_ops.
---
New file added: include/linux/frontswap.h
[v14: add support for writethrough, per suggestion by aarcange@redhat.com]
[v14: rebase to 3.4-rc2]
[v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in]
[v10: no change]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1]
[v8: rebase to 3.0-rc4]
[v7: rebase to 3.0-rc3]
[v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd]
[v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls]
[v6: rebase to 3.1-rc1]
[v5: no change from v4]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
[v15: int/bool on some functions]
Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 17:06:54 -06:00
|
|
|
#ifndef _LINUX_FRONTSWAP_H
|
|
|
|
#define _LINUX_FRONTSWAP_H
|
|
|
|
|
|
|
|
#include <linux/swap.h>
|
|
|
|
#include <linux/mm.h>
|
|
|
|
#include <linux/bitops.h>
|
|
|
|
|
|
|
|
struct frontswap_ops {
|
|
|
|
void (*init)(unsigned);
|
2012-05-15 09:32:15 -06:00
|
|
|
int (*store)(unsigned, pgoff_t, struct page *);
|
|
|
|
int (*load)(unsigned, pgoff_t, struct page *);
|
mm: frontswap: add frontswap header file
Frontswap is the alter ego of cleancache, the "yang" to cleancache's
"yin"... and more precisely frontswap is the provider of anonymous
pages to transcendent memory to nicely complement cleancache's providing
of clean pagecache pages to transcendent memory. For optimal use
of transcendent memory, both are necessary... because a kernel
under memory pressure first reclaims clean pagecache pages and,
when under more memory pressure, starts swapping anonymous pages.
Frontswap and cleancache (which was merged at 3.0) are the "frontends"
and the only necessary changes to the core kernel for transcendent memory;
all other supporting code -- the "backends" -- is implemented as drivers.
See the LWN.net article "Transcendent memory in a nutshell" for a detailed
overview of frontswap and related kernel parts:
https://lwn.net/Articles/454795/
Frontswap code was first posted publicly in January 2009 and on LKML in
May 2009, and has remained functionally stable for nearly three years now.
It is barely invasive, touching only the swap subsystem and adds less
than 100 lines of code to existing swap subsystem code files.
It has improved syntactically substantially between V1 and this posting
of V14, thanks to the review of a few kernel developers, and has adapted
easily to at least one major swap subsystem change. As of 3.4, there are
three in-tree users of frontswap patiently waiting for this patchset and
for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at
2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver
merged at 3.4). In addition, a RFC has been posted for a KVM backend.
The frontswap patchset has been in linux-next since next-110603. Earlier
versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel
and SuSE SLES.
This patch, 1of4, provides the header file for the core code for frontswap
that interfaces between the hooks in the swap subsystem and a frontswap
backend via frontswap_ops.
---
New file added: include/linux/frontswap.h
[v14: add support for writethrough, per suggestion by aarcange@redhat.com]
[v14: rebase to 3.4-rc2]
[v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in]
[v10: no change]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1]
[v8: rebase to 3.0-rc4]
[v7: rebase to 3.0-rc3]
[v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd]
[v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls]
[v6: rebase to 3.1-rc1]
[v5: no change from v4]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
[v15: int/bool on some functions]
Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 17:06:54 -06:00
|
|
|
void (*invalidate_page)(unsigned, pgoff_t);
|
|
|
|
void (*invalidate_area)(unsigned);
|
|
|
|
};
|
|
|
|
|
|
|
|
extern bool frontswap_enabled;
|
|
|
|
extern struct frontswap_ops
|
|
|
|
frontswap_register_ops(struct frontswap_ops *ops);
|
|
|
|
extern void frontswap_shrink(unsigned long);
|
|
|
|
extern unsigned long frontswap_curr_pages(void);
|
|
|
|
extern void frontswap_writethrough(bool);
|
frontswap: support exclusive gets if tmem backend is capable
Tmem, as originally specified, assumes that "get" operations
performed on persistent pools never flush the page of data out
of tmem on a successful get, waiting instead for a flush
operation. This is intended to mimic the model of a swap
disk, where a disk read is non-destructive. Unlike a
disk, however, freeing up the RAM can be valuable. Over
the years that frontswap was in the review process, several
reviewers (and notably Hugh Dickins in 2010) pointed out that
this would result, at least temporarily, in two copies of the
data in RAM: one (compressed for zcache) copy in tmem,
and one copy in the swap cache. We wondered if this could
be done differently, at least optionally.
This patch allows tmem backends to instruct the frontswap
code that this backend performs exclusive gets. Zcache2
already contains hooks to support this feature. Other
backends are completely unaffected unless/until they are
updated to support this feature.
While it is not clear that exclusive gets are a performance
win on all workloads at all times, this small patch allows for
experimentation by backends.
P.S. Let's not quibble about the naming of "get" vs "read" vs
"load" etc. The naming is currently horribly inconsistent between
cleancache and frontswap and existing tmem backends, so will need
to be straightened out as a separate patch. "Get" is used
by the tmem architecture spec, existing backends, and
all documentation and presentation material so I am
using it in this patch.
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-09-20 13:16:52 -06:00
|
|
|
#define FRONTSWAP_HAS_EXCLUSIVE_GETS
|
|
|
|
extern void frontswap_tmem_exclusive_gets(bool);
|
mm: frontswap: add frontswap header file
Frontswap is the alter ego of cleancache, the "yang" to cleancache's
"yin"... and more precisely frontswap is the provider of anonymous
pages to transcendent memory to nicely complement cleancache's providing
of clean pagecache pages to transcendent memory. For optimal use
of transcendent memory, both are necessary... because a kernel
under memory pressure first reclaims clean pagecache pages and,
when under more memory pressure, starts swapping anonymous pages.
Frontswap and cleancache (which was merged at 3.0) are the "frontends"
and the only necessary changes to the core kernel for transcendent memory;
all other supporting code -- the "backends" -- is implemented as drivers.
See the LWN.net article "Transcendent memory in a nutshell" for a detailed
overview of frontswap and related kernel parts:
https://lwn.net/Articles/454795/
Frontswap code was first posted publicly in January 2009 and on LKML in
May 2009, and has remained functionally stable for nearly three years now.
It is barely invasive, touching only the swap subsystem and adds less
than 100 lines of code to existing swap subsystem code files.
It has improved syntactically substantially between V1 and this posting
of V14, thanks to the review of a few kernel developers, and has adapted
easily to at least one major swap subsystem change. As of 3.4, there are
three in-tree users of frontswap patiently waiting for this patchset and
for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at
2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver
merged at 3.4). In addition, a RFC has been posted for a KVM backend.
The frontswap patchset has been in linux-next since next-110603. Earlier
versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel
and SuSE SLES.
This patch, 1of4, provides the header file for the core code for frontswap
that interfaces between the hooks in the swap subsystem and a frontswap
backend via frontswap_ops.
---
New file added: include/linux/frontswap.h
[v14: add support for writethrough, per suggestion by aarcange@redhat.com]
[v14: rebase to 3.4-rc2]
[v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in]
[v10: no change]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1]
[v8: rebase to 3.0-rc4]
[v7: rebase to 3.0-rc3]
[v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd]
[v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls]
[v6: rebase to 3.1-rc1]
[v5: no change from v4]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
[v15: int/bool on some functions]
Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 17:06:54 -06:00
|
|
|
|
|
|
|
extern void __frontswap_init(unsigned type);
|
2012-05-15 09:32:15 -06:00
|
|
|
extern int __frontswap_store(struct page *page);
|
|
|
|
extern int __frontswap_load(struct page *page);
|
mm: frontswap: add frontswap header file
Frontswap is the alter ego of cleancache, the "yang" to cleancache's
"yin"... and more precisely frontswap is the provider of anonymous
pages to transcendent memory to nicely complement cleancache's providing
of clean pagecache pages to transcendent memory. For optimal use
of transcendent memory, both are necessary... because a kernel
under memory pressure first reclaims clean pagecache pages and,
when under more memory pressure, starts swapping anonymous pages.
Frontswap and cleancache (which was merged at 3.0) are the "frontends"
and the only necessary changes to the core kernel for transcendent memory;
all other supporting code -- the "backends" -- is implemented as drivers.
See the LWN.net article "Transcendent memory in a nutshell" for a detailed
overview of frontswap and related kernel parts:
https://lwn.net/Articles/454795/
Frontswap code was first posted publicly in January 2009 and on LKML in
May 2009, and has remained functionally stable for nearly three years now.
It is barely invasive, touching only the swap subsystem and adds less
than 100 lines of code to existing swap subsystem code files.
It has improved syntactically substantially between V1 and this posting
of V14, thanks to the review of a few kernel developers, and has adapted
easily to at least one major swap subsystem change. As of 3.4, there are
three in-tree users of frontswap patiently waiting for this patchset and
for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at
2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver
merged at 3.4). In addition, a RFC has been posted for a KVM backend.
The frontswap patchset has been in linux-next since next-110603. Earlier
versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel
and SuSE SLES.
This patch, 1of4, provides the header file for the core code for frontswap
that interfaces between the hooks in the swap subsystem and a frontswap
backend via frontswap_ops.
---
New file added: include/linux/frontswap.h
[v14: add support for writethrough, per suggestion by aarcange@redhat.com]
[v14: rebase to 3.4-rc2]
[v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in]
[v10: no change]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1]
[v8: rebase to 3.0-rc4]
[v7: rebase to 3.0-rc3]
[v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd]
[v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls]
[v6: rebase to 3.1-rc1]
[v5: no change from v4]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
[v15: int/bool on some functions]
Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 17:06:54 -06:00
|
|
|
extern void __frontswap_invalidate_page(unsigned, pgoff_t);
|
|
|
|
extern void __frontswap_invalidate_area(unsigned);
|
|
|
|
|
|
|
|
#ifdef CONFIG_FRONTSWAP
|
|
|
|
|
|
|
|
static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
|
|
|
|
{
|
|
|
|
bool ret = false;
|
|
|
|
|
|
|
|
if (frontswap_enabled && sis->frontswap_map)
|
|
|
|
ret = test_bit(offset, sis->frontswap_map);
|
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline void frontswap_set(struct swap_info_struct *sis, pgoff_t offset)
|
|
|
|
{
|
|
|
|
if (frontswap_enabled && sis->frontswap_map)
|
|
|
|
set_bit(offset, sis->frontswap_map);
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline void frontswap_clear(struct swap_info_struct *sis, pgoff_t offset)
|
|
|
|
{
|
|
|
|
if (frontswap_enabled && sis->frontswap_map)
|
|
|
|
clear_bit(offset, sis->frontswap_map);
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline void frontswap_map_set(struct swap_info_struct *p,
|
|
|
|
unsigned long *map)
|
|
|
|
{
|
|
|
|
p->frontswap_map = map;
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
|
|
|
|
{
|
|
|
|
return p->frontswap_map;
|
|
|
|
}
|
|
|
|
#else
|
|
|
|
/* all inline routines become no-ops and all externs are ignored */
|
|
|
|
|
|
|
|
#define frontswap_enabled (0)
|
|
|
|
|
|
|
|
static inline bool frontswap_test(struct swap_info_struct *sis, pgoff_t offset)
|
|
|
|
{
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline void frontswap_set(struct swap_info_struct *sis, pgoff_t offset)
|
|
|
|
{
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline void frontswap_clear(struct swap_info_struct *sis, pgoff_t offset)
|
|
|
|
{
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline void frontswap_map_set(struct swap_info_struct *p,
|
|
|
|
unsigned long *map)
|
|
|
|
{
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline unsigned long *frontswap_map_get(struct swap_info_struct *p)
|
|
|
|
{
|
|
|
|
return NULL;
|
|
|
|
}
|
|
|
|
#endif
|
|
|
|
|
2012-05-15 09:32:15 -06:00
|
|
|
static inline int frontswap_store(struct page *page)
|
mm: frontswap: add frontswap header file
Frontswap is the alter ego of cleancache, the "yang" to cleancache's
"yin"... and more precisely frontswap is the provider of anonymous
pages to transcendent memory to nicely complement cleancache's providing
of clean pagecache pages to transcendent memory. For optimal use
of transcendent memory, both are necessary... because a kernel
under memory pressure first reclaims clean pagecache pages and,
when under more memory pressure, starts swapping anonymous pages.
Frontswap and cleancache (which was merged at 3.0) are the "frontends"
and the only necessary changes to the core kernel for transcendent memory;
all other supporting code -- the "backends" -- is implemented as drivers.
See the LWN.net article "Transcendent memory in a nutshell" for a detailed
overview of frontswap and related kernel parts:
https://lwn.net/Articles/454795/
Frontswap code was first posted publicly in January 2009 and on LKML in
May 2009, and has remained functionally stable for nearly three years now.
It is barely invasive, touching only the swap subsystem and adds less
than 100 lines of code to existing swap subsystem code files.
It has improved syntactically substantially between V1 and this posting
of V14, thanks to the review of a few kernel developers, and has adapted
easily to at least one major swap subsystem change. As of 3.4, there are
three in-tree users of frontswap patiently waiting for this patchset and
for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at
2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver
merged at 3.4). In addition, a RFC has been posted for a KVM backend.
The frontswap patchset has been in linux-next since next-110603. Earlier
versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel
and SuSE SLES.
This patch, 1of4, provides the header file for the core code for frontswap
that interfaces between the hooks in the swap subsystem and a frontswap
backend via frontswap_ops.
---
New file added: include/linux/frontswap.h
[v14: add support for writethrough, per suggestion by aarcange@redhat.com]
[v14: rebase to 3.4-rc2]
[v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in]
[v10: no change]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1]
[v8: rebase to 3.0-rc4]
[v7: rebase to 3.0-rc3]
[v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd]
[v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls]
[v6: rebase to 3.1-rc1]
[v5: no change from v4]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
[v15: int/bool on some functions]
Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 17:06:54 -06:00
|
|
|
{
|
|
|
|
int ret = -1;
|
|
|
|
|
|
|
|
if (frontswap_enabled)
|
2012-05-15 09:32:15 -06:00
|
|
|
ret = __frontswap_store(page);
|
mm: frontswap: add frontswap header file
Frontswap is the alter ego of cleancache, the "yang" to cleancache's
"yin"... and more precisely frontswap is the provider of anonymous
pages to transcendent memory to nicely complement cleancache's providing
of clean pagecache pages to transcendent memory. For optimal use
of transcendent memory, both are necessary... because a kernel
under memory pressure first reclaims clean pagecache pages and,
when under more memory pressure, starts swapping anonymous pages.
Frontswap and cleancache (which was merged at 3.0) are the "frontends"
and the only necessary changes to the core kernel for transcendent memory;
all other supporting code -- the "backends" -- is implemented as drivers.
See the LWN.net article "Transcendent memory in a nutshell" for a detailed
overview of frontswap and related kernel parts:
https://lwn.net/Articles/454795/
Frontswap code was first posted publicly in January 2009 and on LKML in
May 2009, and has remained functionally stable for nearly three years now.
It is barely invasive, touching only the swap subsystem and adds less
than 100 lines of code to existing swap subsystem code files.
It has improved syntactically substantially between V1 and this posting
of V14, thanks to the review of a few kernel developers, and has adapted
easily to at least one major swap subsystem change. As of 3.4, there are
three in-tree users of frontswap patiently waiting for this patchset and
for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at
2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver
merged at 3.4). In addition, a RFC has been posted for a KVM backend.
The frontswap patchset has been in linux-next since next-110603. Earlier
versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel
and SuSE SLES.
This patch, 1of4, provides the header file for the core code for frontswap
that interfaces between the hooks in the swap subsystem and a frontswap
backend via frontswap_ops.
---
New file added: include/linux/frontswap.h
[v14: add support for writethrough, per suggestion by aarcange@redhat.com]
[v14: rebase to 3.4-rc2]
[v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in]
[v10: no change]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1]
[v8: rebase to 3.0-rc4]
[v7: rebase to 3.0-rc3]
[v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd]
[v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls]
[v6: rebase to 3.1-rc1]
[v5: no change from v4]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
[v15: int/bool on some functions]
Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 17:06:54 -06:00
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
2012-05-15 09:32:15 -06:00
|
|
|
static inline int frontswap_load(struct page *page)
|
mm: frontswap: add frontswap header file
Frontswap is the alter ego of cleancache, the "yang" to cleancache's
"yin"... and more precisely frontswap is the provider of anonymous
pages to transcendent memory to nicely complement cleancache's providing
of clean pagecache pages to transcendent memory. For optimal use
of transcendent memory, both are necessary... because a kernel
under memory pressure first reclaims clean pagecache pages and,
when under more memory pressure, starts swapping anonymous pages.
Frontswap and cleancache (which was merged at 3.0) are the "frontends"
and the only necessary changes to the core kernel for transcendent memory;
all other supporting code -- the "backends" -- is implemented as drivers.
See the LWN.net article "Transcendent memory in a nutshell" for a detailed
overview of frontswap and related kernel parts:
https://lwn.net/Articles/454795/
Frontswap code was first posted publicly in January 2009 and on LKML in
May 2009, and has remained functionally stable for nearly three years now.
It is barely invasive, touching only the swap subsystem and adds less
than 100 lines of code to existing swap subsystem code files.
It has improved syntactically substantially between V1 and this posting
of V14, thanks to the review of a few kernel developers, and has adapted
easily to at least one major swap subsystem change. As of 3.4, there are
three in-tree users of frontswap patiently waiting for this patchset and
for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at
2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver
merged at 3.4). In addition, a RFC has been posted for a KVM backend.
The frontswap patchset has been in linux-next since next-110603. Earlier
versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel
and SuSE SLES.
This patch, 1of4, provides the header file for the core code for frontswap
that interfaces between the hooks in the swap subsystem and a frontswap
backend via frontswap_ops.
---
New file added: include/linux/frontswap.h
[v14: add support for writethrough, per suggestion by aarcange@redhat.com]
[v14: rebase to 3.4-rc2]
[v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in]
[v10: no change]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1]
[v8: rebase to 3.0-rc4]
[v7: rebase to 3.0-rc3]
[v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd]
[v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls]
[v6: rebase to 3.1-rc1]
[v5: no change from v4]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
[v15: int/bool on some functions]
Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 17:06:54 -06:00
|
|
|
{
|
|
|
|
int ret = -1;
|
|
|
|
|
|
|
|
if (frontswap_enabled)
|
2012-05-15 09:32:15 -06:00
|
|
|
ret = __frontswap_load(page);
|
mm: frontswap: add frontswap header file
Frontswap is the alter ego of cleancache, the "yang" to cleancache's
"yin"... and more precisely frontswap is the provider of anonymous
pages to transcendent memory to nicely complement cleancache's providing
of clean pagecache pages to transcendent memory. For optimal use
of transcendent memory, both are necessary... because a kernel
under memory pressure first reclaims clean pagecache pages and,
when under more memory pressure, starts swapping anonymous pages.
Frontswap and cleancache (which was merged at 3.0) are the "frontends"
and the only necessary changes to the core kernel for transcendent memory;
all other supporting code -- the "backends" -- is implemented as drivers.
See the LWN.net article "Transcendent memory in a nutshell" for a detailed
overview of frontswap and related kernel parts:
https://lwn.net/Articles/454795/
Frontswap code was first posted publicly in January 2009 and on LKML in
May 2009, and has remained functionally stable for nearly three years now.
It is barely invasive, touching only the swap subsystem and adds less
than 100 lines of code to existing swap subsystem code files.
It has improved syntactically substantially between V1 and this posting
of V14, thanks to the review of a few kernel developers, and has adapted
easily to at least one major swap subsystem change. As of 3.4, there are
three in-tree users of frontswap patiently waiting for this patchset and
for CONFIG_FRONTSWAP to be enabled: zcache (staging driver merged at
2.6.39), Xen tmem (merged at 3.0 and 3.1) and RAMster (staging driver
merged at 3.4). In addition, a RFC has been posted for a KVM backend.
The frontswap patchset has been in linux-next since next-110603. Earlier
versions of frontswap already ship in the Oracle Unbreakable Enterprise Kernel
and SuSE SLES.
This patch, 1of4, provides the header file for the core code for frontswap
that interfaces between the hooks in the swap subsystem and a frontswap
backend via frontswap_ops.
---
New file added: include/linux/frontswap.h
[v14: add support for writethrough, per suggestion by aarcange@redhat.com]
[v14: rebase to 3.4-rc2]
[v11: konrad.wilk@oracle.com: squashed s/flush/invalidate/ in]
[v10: no change]
[v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1]
[v8: rebase to 3.0-rc4]
[v7: rebase to 3.0-rc3]
[v7: JBeulich@novell.com: new static inlines resolve to no-ops if not config'd]
[v7: JBeulich@novell.com: avoid redundant shifts/divides for *_bit lib calls]
[v6: rebase to 3.1-rc1]
[v5: no change from v4]
[v4: rebase to 2.6.39]
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Jan Beulich <JBeulich@novell.com>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Rik Riel <riel@redhat.com>
[v15: int/bool on some functions]
Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
2012-04-09 17:06:54 -06:00
|
|
|
return ret;
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline void frontswap_invalidate_page(unsigned type, pgoff_t offset)
|
|
|
|
{
|
|
|
|
if (frontswap_enabled)
|
|
|
|
__frontswap_invalidate_page(type, offset);
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline void frontswap_invalidate_area(unsigned type)
|
|
|
|
{
|
|
|
|
if (frontswap_enabled)
|
|
|
|
__frontswap_invalidate_area(type);
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline void frontswap_init(unsigned type)
|
|
|
|
{
|
|
|
|
if (frontswap_enabled)
|
|
|
|
__frontswap_init(type);
|
|
|
|
}
|
|
|
|
|
|
|
|
#endif /* _LINUX_FRONTSWAP_H */
|