depends on !UML
default y
+config HAVE_IRQ_WORK
+ bool
+
+config IRQ_WORK
+ bool
+ depends on HAVE_IRQ_WORK
+
menu "General setup"
config EXPERIMENTAL
config LOCK_KERNEL
bool
- depends on SMP || PREEMPT
+ depends on (SMP || PREEMPT) && BKL
default y
config INIT_ENV_ARG_LIMIT
variables passed to init from the kernel command line.
+config CROSS_COMPILE
+ string "Cross-compiler tool prefix"
+ help
+ Same as running 'make CROSS_COMPILE=prefix-' but stored for
+ default make runs in this kernel build directory. You don't
+ need to set this unless you want the configured kernel build
+ directory to select the cross-compiler automatically.
+
config LOCALVERSION
string "Local version - append to kernel release"
help
config HAVE_KERNEL_LZMA
bool
+config HAVE_KERNEL_XZ
+ bool
+
+config HAVE_KERNEL_LZO
+ bool
+
choice
prompt "Kernel compression mode"
default KERNEL_GZIP
- depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA
+ depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
help
The linux kernel is a kind of self-extracting executable.
Several compression algorithms are available, which differ
bool "Gzip"
depends on HAVE_KERNEL_GZIP
help
- The old and tried gzip compression. Its compression ratio is
- the poorest among the 3 choices; however its speed (both
- compression and decompression) is the fastest.
+ The old and tried gzip compression. It provides a good balance
+ between compression ratio and decompression speed.
config KERNEL_BZIP2
bool "Bzip2"
two. Compression is slowest. The kernel size is about 33%
smaller with LZMA in comparison to gzip.
+config KERNEL_XZ
+ bool "XZ"
+ depends on HAVE_KERNEL_XZ
+ help
+ XZ uses the LZMA2 algorithm and instruction set specific
+ BCJ filters which can improve compression ratio of executable
+ code. The size of the kernel is about 30% smaller with XZ in
+ comparison to gzip. On architectures for which there is a BCJ
+ filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
+ will create a few percent smaller kernel than plain LZMA.
+
+ The speed is about the same as with LZMA: The decompression
+ speed of XZ is better than that of bzip2 but worse than gzip
+ and LZO. Compression is slow.
+
+config KERNEL_LZO
+ bool "LZO"
+ depends on HAVE_KERNEL_LZO
+ help
+ Its compression ratio is the poorest among the 4. The kernel
+ size is about 10% bigger than gzip; however its speed
+ (both compression and decompression) is the fastest.
+
endchoice
config SWAP
config AUDITSYSCALL
bool "Enable system-call auditing support"
- depends on AUDIT && (X86 || PPC || PPC64 || S390 || IA64 || UML || SPARC64|| SUPERH)
+ depends on AUDIT && (X86 || PPC || S390 || IA64 || UML || SPARC64 || SUPERH)
default y if SECURITY_SELINUX
help
Enable low-overhead system-call auditing infrastructure that
can be used independently or with another kernel subsystem,
- such as SELinux. To use audit's filesystem watch feature, please
- ensure that INOTIFY is configured.
+ such as SELinux.
+
+config AUDIT_WATCH
+ def_bool y
+ depends on AUDITSYSCALL
+ select FSNOTIFY
config AUDIT_TREE
def_bool y
depends on AUDITSYSCALL
- select INOTIFY
+ select FSNOTIFY
+
+source "kernel/irq/Kconfig"
menu "RCU Subsystem"
prompt "RCU Implementation"
default TREE_RCU
-config CLASSIC_RCU
- bool "Classic RCU"
- help
- This option selects the classic RCU implementation that is
- designed for best read-side performance on non-realtime
- systems.
-
- Select this option if you are unsure.
-
config TREE_RCU
bool "Tree-based hierarchical RCU"
+ depends on !PREEMPT && SMP
help
This option selects the RCU implementation that is
designed for very large SMP system with hundreds or
- thousands of CPUs.
+ thousands of CPUs. It also scales down nicely to
+ smaller systems.
-config PREEMPT_RCU
- bool "Preemptible RCU"
+config TREE_PREEMPT_RCU
+ bool "Preemptible tree-based hierarchical RCU"
depends on PREEMPT
help
- This option reduces the latency of the kernel by making certain
- RCU sections preemptible. Normally RCU code is non-preemptible, if
- this option is selected then read-only RCU sections become
- preemptible. This helps latency, but may expose bugs due to
- now-naive assumptions about each RCU read-side critical section
- remaining on a given CPU through its execution.
+ This option selects the RCU implementation that is
+ designed for very large SMP systems with hundreds or
+ thousands of CPUs, but for which real-time response
+ is also required. It also scales down nicely to
+ smaller systems.
+
+config TINY_RCU
+ bool "UP-only small-memory-footprint RCU"
+ depends on !SMP
+ help
+ This option selects the RCU implementation that is
+ designed for UP systems from which real-time response
+ is not required. This option greatly reduces the
+ memory footprint of RCU.
+
+config TINY_PREEMPT_RCU
+ bool "Preemptible UP-only small-memory-footprint RCU"
+ depends on !SMP && PREEMPT
+ help
+ This option selects the RCU implementation that is designed
+ for real-time UP systems. This option greatly reduces the
+ memory footprint of RCU.
endchoice
+config PREEMPT_RCU
+ def_bool ( TREE_PREEMPT_RCU || TINY_PREEMPT_RCU )
+ help
+ This option enables preemptible-RCU code that is common between
+ the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.
+
config RCU_TRACE
bool "Enable tracing for RCU"
- depends on TREE_RCU || PREEMPT_RCU
help
This option provides tracing in RCU which presents stats
in debugfs for debugging RCU implementation.
int "Tree-based hierarchical RCU fanout value"
range 2 64 if 64BIT
range 2 32 if !64BIT
- depends on TREE_RCU
+ depends on TREE_RCU || TREE_PREEMPT_RCU
default 64 if 64BIT
default 32 if !64BIT
help
This option controls the fanout of hierarchical implementations
of RCU, allowing RCU to work efficiently on machines with
- large numbers of CPUs. This value must be at least the cube
- root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit
- systems and up to 262,144 for 64-bit systems.
+ large numbers of CPUs. This value must be at least the fourth
+ root of NR_CPUS, which allows NR_CPUS to be insanely large.
+ The default value of RCU_FANOUT should be used for production
+ systems, but if you are stress-testing the RCU implementation
+ itself, small RCU_FANOUT values allow you to test large-system
+ code paths on small(er) systems.
Select a specific number if testing RCU itself.
Take the default if unsure.
config RCU_FANOUT_EXACT
bool "Disable tree-based hierarchical RCU auto-balancing"
- depends on TREE_RCU
+ depends on TREE_RCU || TREE_PREEMPT_RCU
default n
help
This option forces use of the exact RCU_FANOUT value specified,
Say N if unsure.
+config RCU_FAST_NO_HZ
+ bool "Accelerate last non-dyntick-idle CPU's grace periods"
+ depends on TREE_RCU && NO_HZ && SMP
+ default n
+ help
+ This option causes RCU to attempt to accelerate grace periods
+ in order to allow the final CPU to enter dynticks-idle state
+ more quickly. On the other hand, this option increases the
+ overhead of the dynticks-idle checking, particularly on systems
+ with large numbers of CPUs.
+
+ Say Y if energy efficiency is critically important, particularly
+ if you have relatively few CPUs.
+
+ Say N if you are unsure.
+
config TREE_RCU_TRACE
- def_bool RCU_TRACE && TREE_RCU
+ def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU )
select DEBUG_FS
help
- This option provides tracing for the TREE_RCU implementation,
- permitting Makefile to trivially select kernel/rcutree_trace.c.
+ This option provides tracing for the TREE_RCU and
+ TREE_PREEMPT_RCU implementations, permitting Makefile to
+ trivially select kernel/rcutree_trace.c.
-config PREEMPT_RCU_TRACE
- def_bool RCU_TRACE && PREEMPT_RCU
- select DEBUG_FS
+config RCU_BOOST
+ bool "Enable RCU priority boosting"
+ depends on RT_MUTEXES && TINY_PREEMPT_RCU
+ default n
help
- This option provides tracing for the PREEMPT_RCU implementation,
- permitting Makefile to trivially select kernel/rcupreempt_trace.c.
+ This option boosts the priority of preempted RCU readers that
+ block the current preemptible RCU grace period for too long.
+ This option also prevents heavy loads from blocking RCU
+ callback invocation for all flavors of RCU.
+
+ Say Y here if you are working with real-time apps or heavy loads
+ Say N here if you are unsure.
+
+config RCU_BOOST_PRIO
+ int "Real-time priority to boost RCU readers to"
+ range 1 99
+ depends on RCU_BOOST
+ default 1
+ help
+ This option specifies the real-time priority to which preempted
+ RCU readers are to be boosted. If you are working with CPU-bound
+ real-time applications, you should specify a priority higher then
+ the highest-priority CPU-bound application.
+
+ Specify the real-time priority, or take the default if unsure.
+
+config RCU_BOOST_DELAY
+ int "Milliseconds to delay boosting after RCU grace-period start"
+ range 0 3000
+ depends on RCU_BOOST
+ default 500
+ help
+ This option specifies the time to wait after the beginning of
+ a given grace period before priority-boosting preempted RCU
+ readers blocking that grace period. Note that any RCU reader
+ blocking an expedited RCU grace period is boosted immediately.
+
+ Accept the default if unsure.
endmenu # "RCU Subsystem"
config HAVE_UNSTABLE_SCHED_CLOCK
bool
-config GROUP_SCHED
- bool "Group CPU scheduler"
- depends on EXPERIMENTAL
- default n
- help
- This feature lets CPU scheduler recognize task groups and control CPU
- bandwidth allocation to such task groups.
- In order to create a group from arbitrary set of processes, use
- CONFIG_CGROUPS. (See Control Group support.)
-
-config FAIR_GROUP_SCHED
- bool "Group scheduling for SCHED_OTHER"
- depends on GROUP_SCHED
- default GROUP_SCHED
-
-config RT_GROUP_SCHED
- bool "Group scheduling for SCHED_RR/FIFO"
- depends on EXPERIMENTAL
- depends on GROUP_SCHED
- default n
- help
- This feature lets you explicitly allocate real CPU bandwidth
- to users or control groups (depending on the "Basis for grouping tasks"
- setting below. If enabled, it will also make it impossible to
- schedule realtime tasks for non-root users until you allocate
- realtime bandwidth for them.
- See Documentation/scheduler/sched-rt-group.txt for more information.
-
-choice
- depends on GROUP_SCHED
- prompt "Basis for grouping tasks"
- default USER_SCHED
-
-config USER_SCHED
- bool "user id"
- help
- This option will choose userid as the basis for grouping
- tasks, thus providing equal CPU bandwidth to each user.
-
-config CGROUP_SCHED
- bool "Control groups"
- depends on CGROUPS
- help
- This option allows you to create arbitrary task groups
- using the "cgroup" pseudo filesystem and control
- the cpu bandwidth allocated to each such task group.
- Refer to Documentation/cgroups/cgroups.txt for more
- information on "cgroup" pseudo filesystem.
-
-endchoice
-
menuconfig CGROUPS
boolean "Control Group support"
+ depends on EVENTFD
help
This option adds support for grouping sets of processes together, for
use with process control subsystems such as Cpusets, CFS, memory
config CGROUP_DEBUG
bool "Example debug cgroup subsystem"
- depends on CGROUPS
default n
help
This option enables a simple cgroup subsystem that
config CGROUP_NS
bool "Namespace cgroup subsystem"
- depends on CGROUPS
help
Provides a simple namespace cgroup subsystem to
provide hierarchical naming of sets of namespaces,
config CGROUP_FREEZER
bool "Freezer cgroup subsystem"
- depends on CGROUPS
help
Provides a way to freeze and unfreeze all tasks in a
cgroup.
config CGROUP_DEVICE
bool "Device controller for cgroups"
- depends on CGROUPS && EXPERIMENTAL
help
Provides a cgroup implementing whitelists for devices which
a process in the cgroup can mknod or open.
config CPUSETS
bool "Cpuset support"
- depends on CGROUPS
help
This option will let you create and manage CPUSETs which
allow dynamically partitioning a system into sets of CPUs and
config CGROUP_CPUACCT
bool "Simple CPU accounting cgroup subsystem"
- depends on CGROUPS
help
Provides a simple Resource Controller for monitoring the
total CPU consumed by the tasks in a cgroup.
help
This option enables controller independent resource accounting
infrastructure that works with cgroups.
- depends on CGROUPS
config CGROUP_MEM_RES_CTLR
bool "Memory Resource Controller for Control Groups"
- depends on CGROUPS && RESOURCE_COUNTERS
+ depends on RESOURCE_COUNTERS
select MM_OWNER
help
Provides a memory resource controller that manages both anonymous
could in turn add some fork/exit overhead.
config CGROUP_MEM_RES_CTLR_SWAP
- bool "Memory Resource Controller Swap Extension(EXPERIMENTAL)"
- depends on CGROUP_MEM_RES_CTLR && SWAP && EXPERIMENTAL
+ bool "Memory Resource Controller Swap Extension"
+ depends on CGROUP_MEM_RES_CTLR && SWAP
help
Add swap management feature to memory resource controller. When you
enable this, you can limit mem+swap usage per cgroup. In other words,
if boot option "noswapaccount" is set, swap will not be accounted.
Now, memory usage of swap_cgroup is 2 bytes per entry. If swap page
size is 4096bytes, 512k per 1Gbytes of swap.
+config CGROUP_MEM_RES_CTLR_SWAP_ENABLED
+ bool "Memory Resource Controller Swap Extension enabled by default"
+ depends on CGROUP_MEM_RES_CTLR_SWAP
+ default y
+ help
+ Memory Resource Controller Swap Extension comes with its price in
+ a bigger memory consumption. General purpose distribution kernels
+ which want to enable the feature but keep it disabled by default
+ and let the user enable it by swapaccount boot command line
+ parameter should have this option unselected.
+ For those who want to have the feature enabled by default should
+ select this option (if, for some reason, they need to disable it
+ then noswapaccount does the trick).
-endif # CGROUPS
-
-config MM_OWNER
- bool
+menuconfig CGROUP_SCHED
+ bool "Group CPU scheduler"
+ depends on EXPERIMENTAL
+ default n
+ help
+ This feature lets CPU scheduler recognize task groups and control CPU
+ bandwidth allocation to such task groups. It uses cgroups to group
+ tasks.
-config SYSFS_DEPRECATED
- bool
+if CGROUP_SCHED
+config FAIR_GROUP_SCHED
+ bool "Group scheduling for SCHED_OTHER"
+ depends on CGROUP_SCHED
+ default CGROUP_SCHED
-config SYSFS_DEPRECATED_V2
- bool "remove sysfs features which may confuse old userspace tools"
- depends on SYSFS
+config RT_GROUP_SCHED
+ bool "Group scheduling for SCHED_RR/FIFO"
+ depends on EXPERIMENTAL
+ depends on CGROUP_SCHED
default n
- select SYSFS_DEPRECATED
- help
- This option switches the layout of sysfs to the deprecated
- version. Do not use it on recent distributions.
-
- The current sysfs layout features a unified device tree at
- /sys/devices/, which is able to express a hierarchy between
- class devices. If the deprecated option is set to Y, the
- unified device tree is split into a bus device tree at
- /sys/devices/ and several individual class device trees at
- /sys/class/. The class and bus devices will be connected by
- "<subsystem>:<name>" and the "device" links. The "block"
- class devices, will not show up in /sys/class/block/. Some
- subsystems will suppress the creation of some devices which
- depend on the unified device tree.
-
- This option is not a pure compatibility option that can
- be safely enabled on newer distributions. It will change the
- layout of sysfs to the non-extensible deprecated version,
- and disable some features, which can not be exported without
- confusing older userspace tools. Since 2007/2008 all major
- distributions do not enable this option, and ship no tools which
- depend on the deprecated layout or this option.
-
- If you are using a new kernel on an older distribution, or use
- older userspace tools, you might need to say Y here. Do not say Y,
- if the original kernel, that came with your distribution, has
- this option set to N.
-
-config RELAY
- bool "Kernel->user space relay support (formerly relayfs)"
help
- This option enables support for relay interface support in
- certain file systems (such as debugfs).
- It is designed to provide an efficient mechanism for tools and
- facilities to relay large amounts of data from kernel space to
- user space.
+ This feature lets you explicitly allocate real CPU bandwidth
+ to task groups. If enabled, it will also make it impossible to
+ schedule realtime tasks for non-root users until you allocate
+ realtime bandwidth for them.
+ See Documentation/scheduler/sched-rt-group.txt for more information.
- If unsure, say N.
+endif #CGROUP_SCHED
+
+config BLK_CGROUP
+ tristate "Block IO controller"
+ depends on BLOCK
+ default n
+ ---help---
+ Generic block IO controller cgroup interface. This is the common
+ cgroup interface which should be used by various IO controlling
+ policies.
+
+ Currently, CFQ IO scheduler uses it to recognize task groups and
+ control disk bandwidth allocation (proportional time slice allocation)
+ to such task groups. It is also used by bio throttling logic in
+ block layer to implement upper limit in IO rates on a device.
+
+ This option only enables generic Block IO controller infrastructure.
+ One needs to also enable actual IO controlling logic/policy. For
+ enabling proportional weight division of disk bandwidth in CFQ seti
+ CONFIG_CFQ_GROUP_IOSCHED=y and for enabling throttling policy set
+ CONFIG_BLK_THROTTLE=y.
+
+ See Documentation/cgroups/blkio-controller.txt for more information.
+
+config DEBUG_BLK_CGROUP
+ bool "Enable Block IO controller debugging"
+ depends on BLK_CGROUP
+ default n
+ ---help---
+ Enable some debugging help. Currently it exports additional stat
+ files in a cgroup which can be useful for debugging.
+
+endif # CGROUPS
-config NAMESPACES
+menuconfig NAMESPACES
bool "Namespaces support" if EMBEDDED
default !EMBEDDED
help
or same user id or pid may refer to different tasks when used in
different namespaces.
+if NAMESPACES
+
config UTS_NS
bool "UTS namespace"
- depends on NAMESPACES
+ default y
help
In this namespace tasks see different info provided with the
uname() system call
config IPC_NS
bool "IPC namespace"
- depends on NAMESPACES && (SYSVIPC || POSIX_MQUEUE)
+ depends on (SYSVIPC || POSIX_MQUEUE)
+ default y
help
In this namespace tasks work with IPC ids which correspond to
different IPC objects in different namespaces.
config USER_NS
bool "User namespace (EXPERIMENTAL)"
- depends on NAMESPACES && EXPERIMENTAL
+ depends on EXPERIMENTAL
+ default y
help
This allows containers, i.e. vservers, to use user namespaces
to provide different user info for different servers.
If unsure, say N.
config PID_NS
- bool "PID Namespaces (EXPERIMENTAL)"
- default n
- depends on NAMESPACES && EXPERIMENTAL
+ bool "PID Namespaces"
+ default y
help
Support process id namespaces. This allows having multiple
processes with the same pid as long as they are in different
pid namespaces. This is a building block of containers.
- Unless you want to work with an experimental feature
- say N here.
-
config NET_NS
bool "Network namespace"
- default n
- depends on NAMESPACES && EXPERIMENTAL && NET
+ depends on NET
+ default y
help
Allow user space to create what appear to be multiple instances
of the network stack.
+endif # NAMESPACES
+
+config SCHED_AUTOGROUP
+ bool "Automatic process group scheduling"
+ select EVENTFD
+ select CGROUPS
+ select CGROUP_SCHED
+ select FAIR_GROUP_SCHED
+ help
+ This option optimizes the scheduler for common desktop workloads by
+ automatically creating and populating task groups. This separation
+ of workloads isolates aggressive CPU burners (like build jobs) from
+ desktop applications. Task group autogeneration is currently based
+ upon task session.
+
+config MM_OWNER
+ bool
+
+config SYSFS_DEPRECATED
+ bool "enable deprecated sysfs features to support old userspace tools"
+ depends on SYSFS
+ default n
+ help
+ This option adds code that switches the layout of the "block" class
+ devices, to not show up in /sys/class/block/, but only in
+ /sys/block/.
+
+ This switch is only active when the sysfs.deprecated=1 boot option is
+ passed or the SYSFS_DEPRECATED_V2 option is set.
+
+ This option allows new kernels to run on old distributions and tools,
+ which might get confused by /sys/class/block/. Since 2007/2008 all
+ major distributions and tools handle this just fine.
+
+ Recent distributions and userspace tools after 2009/2010 depend on
+ the existence of /sys/class/block/, and will not work with this
+ option enabled.
+
+ Only if you are using a new kernel on an old distribution, you might
+ need to say Y here.
+
+config SYSFS_DEPRECATED_V2
+ bool "enabled deprecated sysfs features by default"
+ default n
+ depends on SYSFS
+ depends on SYSFS_DEPRECATED
+ help
+ Enable deprecated sysfs by default.
+
+ See the CONFIG_SYSFS_DEPRECATED option for more details about this
+ option.
+
+ Only if you are using a new kernel on an old distribution, you might
+ need to say Y here. Even then, odds are you would not need it
+ enabled, you can always pass the boot option if absolutely necessary.
+
+config RELAY
+ bool "Kernel->user space relay support (formerly relayfs)"
+ help
+ This option enables support for relay interface support in
+ certain file systems (such as debugfs).
+ It is designed to provide an efficient mechanism for tools and
+ facilities to relay large amounts of data from kernel space to
+ user space.
+
+ If unsure, say N.
+
config BLK_DEV_INITRD
bool "Initial RAM filesystem and RAM disk (initramfs/initrd) support"
depends on BROKEN || !FRV
config SYSCTL_SYSCALL
bool "Sysctl syscall support" if EMBEDDED
+ depends on PROC_SYSCTL
default y
select SYSCTL
---help---
by some high performance threaded applications. Disabling
this option saves about 7k.
-config HAVE_PERF_COUNTERS
+config HAVE_PERF_EVENTS
bool
help
See tools/perf/design.txt for details.
-menu "Performance Counters"
+config PERF_USE_VMALLOC
+ bool
+ help
+ See tools/perf/design.txt for details
+
+menu "Kernel Performance Events And Counters"
-config PERF_COUNTERS
- bool "Kernel Performance Counters"
- default y if PROFILING
- depends on HAVE_PERF_COUNTERS
+config PERF_EVENTS
+ bool "Kernel performance events and counters"
+ default y if (PROFILING || PERF_COUNTERS)
+ depends on HAVE_PERF_EVENTS
select ANON_INODES
+ select IRQ_WORK
help
- Enable kernel support for performance counter hardware.
+ Enable kernel support for various performance events provided
+ by software and hardware.
+
+ Software events are supported either built-in or via the
+ use of generic tracepoints.
- Performance counters are special hardware registers available
- on most modern CPUs. These registers count the number of certain
+ Most modern CPUs support performance events via performance
+ counter registers. These registers count the number of certain
types of hw events: such as instructions executed, cachemisses
suffered, or branches mis-predicted - without slowing down the
kernel or applications. These registers can also trigger interrupts
when a threshold number of events have passed - and can thus be
used to profile the code that runs on that CPU.
- The Linux Performance Counter subsystem provides an abstraction of
- these hardware capabilities, available via a system call. It
+ The Linux Performance Event subsystem provides an abstraction of
+ these software and hardware event capabilities, available via a
+ system call and used by the "perf" utility in tools/perf/. It
provides per task and per CPU counters, and it provides event
capabilities on top of those.
Say Y if unsure.
-config EVENT_PROFILE
- bool "Tracepoint profiling sources"
- depends on PERF_COUNTERS && EVENT_TRACING
- default y
+config PERF_COUNTERS
+ bool "Kernel performance counters (old config option)"
+ depends on HAVE_PERF_EVENTS
+ help
+ This config has been obsoleted by the PERF_EVENTS
+ config option - please see that one for details.
+
+ It has no effect on the kernel whether you enable
+ it or not, it is a compatibility placeholder.
+
+ Say N if unsure.
+
+config DEBUG_PERF_USE_VMALLOC
+ default n
+ bool "Debug: use vmalloc to back perf mmap() buffers"
+ depends on PERF_EVENTS && DEBUG_KERNEL
+ select PERF_USE_VMALLOC
help
- Allow the use of tracepoints as software performance counters.
+ Use vmalloc memory to back perf mmap() buffers.
- When this is enabled, you can create perf counters based on
- tracepoints using PERF_TYPE_TRACEPOINT and the tracepoint ID
- found in debugfs://tracing/events/*/*/id. (The -e/--events
- option to the perf tool can parse and interpret symbolic
- tracepoints, in the subsystem:tracepoint_name format.)
+ Mostly useful for debugging the vmalloc code on platforms
+ that don't require it.
+
+ Say N if unsure.
endmenu
SLUB sysfs support. /sys/slab will not exist and there will be
no support for cache validation etc.
-config STRIP_ASM_SYMS
- bool "Strip assembler-generated symbols during link"
- default n
- help
- Strip internal assembler-generated symbols during a link (symbols
- that look like '.Lxxx') so they don't pollute the output of
- get_wchan() and suchlike.
-
config COMPAT_BRK
bool "Disable heap randomization"
default y
endchoice
+config MMAP_ALLOW_UNINITIALIZED
+ bool "Allow mmapped anonymous memory to be uninitialized"
+ depends on EMBEDDED && !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 (EXPERIMENTAL)"
+ bool "Profiling support"
help
Say Y here to enable the extended profiling support mechanisms used
by profilers such as OProfile.
config TRACEPOINTS
bool
-config MARKERS
- bool "Activate markers"
- select TRACEPOINTS
- help
- Place an empty function call at each marker site. Can be
- dynamically changed for a probe function.
-
source "arch/Kconfig"
-config SLOW_WORK
- default n
- bool
- help
- The slow work thread pool provides a number of dynamically allocated
- threads that can be used by the kernel to perform operations that
- take a relatively long time.
-
- An example of this would be CacheFiles doing a path lookup followed
- by a series of mkdirs and a create call, all of which have to touch
- disk.
-
- See Documentation/slow-work.txt.
-
endmenu # General setup
config HAVE_GENERIC_DMA_COHERENT
config PREEMPT_NOTIFIERS
bool
+config PADATA
+ depends on SMP
+ bool
+
+source "kernel/Kconfig.locks"