From: Dave Hansen <dave.han...@linux.intel.com>
This continues in a series of patches to clean up the
configuration menus. I believe they've become really hard to
navigate and there are some simple things we can do to make
things easier to find.
This creates a "Memory Options" menu and moves some things like
swap and slab configuration under them. It also moves SLUB_DEBUG
to the debugging menu.
After this patch, the menu has the following options:
[ ] Memory placement aware NUMA scheduler
[*] Enable VM event counters for /proc/vmstat
[ ] Disable heap randomization
[*] Support for paging of anonymous memory (swap)
Choose SLAB allocator (SLUB (Unqueued Allocator))
[*] SLUB per cpu partial cache
[*] SLUB: attempt to use double-cmpxchg operations
Signed-off-by: Dave Hansen <dave.han...@linux.intel.com>
Cc: linux...@kvack.org
---
b/init/Kconfig | 243 +++++++++++++++++++++++++++--------------------------
b/mm/Kconfig.debug | 11 ++
2 files changed, 135 insertions(+), 119 deletions(-)
diff -puN init/Kconfig~organize-memory-config-options init/Kconfig
--- a/init/Kconfig~organize-memory-config-options 2014-01-31
09:24:17.328464183 -0800
+++ b/init/Kconfig 2014-01-31 09:24:17.334464455 -0800
@@ -208,16 +208,6 @@ config DEFAULT_HOSTNAME
but you may wish to use a different default here to make a minimal
system more usable with less configuration.
-config SWAP
- bool "Support for paging of anonymous memory (swap)"
- depends on MMU && BLOCK
- default y
- help
- This option allows you to choose whether you want to have support
- for so called swap devices or swap files in your kernel that are
- used to provide more virtual memory than the actual RAM present
- in your computer. If unsure say Y.
-
config SYSVIPC
bool "System V IPC"
---help---
@@ -760,6 +750,130 @@ endchoice
endmenu # "RCU Subsystem"
+menu "Memory Options"
+
+config NUMA_BALANCING
+ bool "Memory placement aware NUMA scheduler"
+ depends on ARCH_SUPPORTS_NUMA_BALANCING
+ depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
+ depends on SMP && NUMA && MIGRATION
+ help
+ This option adds support for automatic NUMA aware memory/task
placement.
+ The mechanism is quite primitive and is based on migrating memory when
+ it has references to the node the task is running on.
+
+ This system will be inactive on UMA systems.
+
+config VM_EVENT_COUNTERS
+ default y
+ bool "Enable VM event counters for /proc/vmstat" if EXPERT
+ help
+ VM event counters are needed for event counts to be shown.
+ This option allows the disabling of the VM event counters
+ on EXPERT systems. /proc/vmstat will only show page counts
+ if VM event counters are disabled.
+
+config COMPAT_BRK
+ bool "Disable heap randomization"
+ default y
+ help
+ Randomizing heap placement makes heap exploits harder, but it
+ also breaks ancient binaries (including anything libc5 based).
+ This option changes the bootup default to heap randomization
+ disabled, and can be overridden at runtime by setting
+ /proc/sys/kernel/randomize_va_space to 2.
+
+ On non-ancient distros (post-2000 ones) N is usually a safe choice.
+
+config SWAP
+ bool "Support for paging of anonymous memory (swap)"
+ depends on MMU && BLOCK
+ default y
+ help
+ This option allows you to choose whether you want to have support
+ for so called swap devices or swap files in your kernel that are
+ used to provide more virtual memory than the actual RAM present
+ in your computer. If unsure say Y.
+
+choice
+ prompt "Choose SLAB allocator"
+ default SLUB
+ help
+ This option allows to select a slab allocator.
+
+config SLAB
+ bool "SLAB"
+ help
+ The regular slab allocator that is established and known to work
+ well in all environments. It organizes cache hot objects in
+ per cpu and per node queues.
+
+config SLUB
+ bool "SLUB (Unqueued Allocator)"
+ help
+ SLUB is a slab allocator that minimizes cache line usage
+ instead of managing queues of cached objects (SLAB approach).
+ Per cpu caching is realized using slabs of objects instead
+ of queues of objects. SLUB can use memory efficiently
+ and has enhanced diagnostics. SLUB is the default choice for
+ a slab allocator.
+
+config SLOB
+ depends on EXPERT
+ bool "SLOB (Simple Allocator)"
+ help
+ SLOB replaces the stock allocator with a drastically simpler
+ allocator. SLOB is generally more space efficient but
+ does not perform as well on large systems.
+
+endchoice
+
+config SLUB_CPU_PARTIAL
+ default y
+ depends on SLUB && SMP
+ bool "SLUB per cpu partial cache"
+ help
+ Per cpu partial caches accellerate objects allocation and freeing
+ that is local to a processor at the price of more indeterminism
+ in the latency of the free. On overflow these caches will be cleared
+ which requires the taking of locks that may cause latency spikes.
+ Typically one would choose no for a realtime system.
+
+config SLUB_ATTEMPT_CMPXCHG_DOUBLE
+ default y
+ depends on SLUB && HAVE_CMPXCHG_DOUBLE
+ bool "SLUB: attempt to use double-cmpxchg operations"
+ help
+ Some CPUs support instructions that let you do a large double-word
+ atomic cmpxchg operation. This keeps the SLUB fastpath from
+ needing to disable interrupts.
+
+ If you are unsure, say y.
+
+config MMAP_ALLOW_UNINITIALIZED
+ bool "Allow mmapped anonymous memory to be uninitialized"
+ depends on EXPERT && !MMU
+ default n
+ help
+ Normally, and according to the Linux spec, anonymous memory obtained
+ from mmap() has it's contents cleared before it is passed to
+ userspace. Enabling this config option allows you to request that
+ mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
+ providing a huge performance boost. If this option is not enabled,
+ then the flag will be ignored.
+
+ This is taken advantage of by uClibc's malloc(), and also by
+ ELF-FDPIC binfmt's brk and stack allocator.
+
+ Because of the obvious security issues, this option should only be
+ enabled on embedded devices where you control what is run in
+ userspace. Since that isn't generally a problem on no-MMU systems,
+ it is normally safe to say Y here.
+
+ See Documentation/nommu-mmap.txt for more information.
+
+endmenu # "Memory Optionse
+
config IKCONFIG
tristate "Kernel .config support"
---help---
@@ -840,18 +954,6 @@ config NUMA_BALANCING_DEFAULT_ENABLED
If set, automatic NUMA balancing will be enabled if running on a NUMA
machine.
-config NUMA_BALANCING
- bool "Memory placement aware NUMA scheduler"
- depends on ARCH_SUPPORTS_NUMA_BALANCING
- depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
- depends on SMP && NUMA && MIGRATION
- help
- This option adds support for automatic NUMA aware memory/task
placement.
- The mechanism is quite primitive and is based on migrating memory when
- it has references to the node the task is running on.
-
- This system will be inactive on UMA systems.
-
menuconfig CGROUPS
boolean "Control Group support"
help
@@ -1517,103 +1619,6 @@ config DEBUG_PERF_USE_VMALLOC
endmenu
-config VM_EVENT_COUNTERS
- default y
- bool "Enable VM event counters for /proc/vmstat" if EXPERT
- help
- VM event counters are needed for event counts to be shown.
- This option allows the disabling of the VM event counters
- on EXPERT systems. /proc/vmstat will only show page counts
- if VM event counters are disabled.
-
-config SLUB_DEBUG
- default y
- bool "Enable SLUB debugging support" if EXPERT
- depends on SLUB && SYSFS
- help
- SLUB has extensive debug support features. Disabling these can
- result in significant savings in code size. This also disables
- SLUB sysfs support. /sys/slab will not exist and there will be
- no support for cache validation etc.
-
-config COMPAT_BRK
- bool "Disable heap randomization"
- default y
- help
- Randomizing heap placement makes heap exploits harder, but it
- also breaks ancient binaries (including anything libc5 based).
- This option changes the bootup default to heap randomization
- disabled, and can be overridden at runtime by setting
- /proc/sys/kernel/randomize_va_space to 2.
-
- On non-ancient distros (post-2000 ones) N is usually a safe choice.
-
-choice
- prompt "Choose SLAB allocator"
- default SLUB
- help
- This option allows to select a slab allocator.
-
-config SLAB
- bool "SLAB"
- help
- The regular slab allocator that is established and known to work
- well in all environments. It organizes cache hot objects in
- per cpu and per node queues.
-
-config SLUB
- bool "SLUB (Unqueued Allocator)"
- help
- SLUB is a slab allocator that minimizes cache line usage
- instead of managing queues of cached objects (SLAB approach).
- Per cpu caching is realized using slabs of objects instead
- of queues of objects. SLUB can use memory efficiently
- and has enhanced diagnostics. SLUB is the default choice for
- a slab allocator.
-
-config SLOB
- depends on EXPERT
- bool "SLOB (Simple Allocator)"
- help
- SLOB replaces the stock allocator with a drastically simpler
- allocator. SLOB is generally more space efficient but
- does not perform as well on large systems.
-
-endchoice
-
-config SLUB_CPU_PARTIAL
- default y
- depends on SLUB && SMP
- bool "SLUB per cpu partial cache"
- help
- Per cpu partial caches accellerate objects allocation and freeing
- that is local to a processor at the price of more indeterminism
- in the latency of the free. On overflow these caches will be cleared
- which requires the taking of locks that may cause latency spikes.
- Typically one would choose no for a realtime system.
-
-config MMAP_ALLOW_UNINITIALIZED
- bool "Allow mmapped anonymous memory to be uninitialized"
- depends on EXPERT && !MMU
- default n
- help
- Normally, and according to the Linux spec, anonymous memory obtained
- from mmap() has it's contents cleared before it is passed to
- userspace. Enabling this config option allows you to request that
- mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
- providing a huge performance boost. If this option is not enabled,
- then the flag will be ignored.
-
- This is taken advantage of by uClibc's malloc(), and also by
- ELF-FDPIC binfmt's brk and stack allocator.
-
- Because of the obvious security issues, this option should only be
- enabled on embedded devices where you control what is run in
- userspace. Since that isn't generally a problem on no-MMU systems,
- it is normally safe to say Y here.
-
- See Documentation/nommu-mmap.txt for more information.
-
config PROFILING
bool "Profiling support"
help
diff -puN mm/Kconfig.debug~organize-memory-config-options mm/Kconfig.debug
--- a/mm/Kconfig.debug~organize-memory-config-options 2014-01-31
09:24:17.330464274 -0800
+++ b/mm/Kconfig.debug 2014-01-31 09:24:17.334464455 -0800
@@ -27,3 +27,14 @@ config PAGE_POISONING
config PAGE_GUARD
bool
select WANT_PAGE_DEBUG_FLAGS
+
+config SLUB_DEBUG
+ default y
+ bool "Enable SLUB debugging support" if EXPERT
+ depends on SLUB && SYSFS
+ help
+ SLUB has extensive debug support features. Disabling these can
+ result in significant savings in code size. This also disables
+ SLUB sysfs support. /sys/slab will not exist and there will be
+ no support for cache validation etc.
+
_
--
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