queues every message has a priority which decides about succession
of receiving it by a process. If you want to compile and run
programs written e.g. for Solaris with use of its POSIX message
- queues (functions mq_*) say Y here. To use this feature you will
- also need mqueue library, available from
- <http://www.mat.uni.torun.pl/~wrona/posix_ipc/>
+ queues (functions mq_*) say Y here.
POSIX message queues are visible as a filesystem called 'mqueue'
and can be mounted somewhere if you want to do filesystem
support for "fast userspace mutexes". The resulting kernel may not
run glibc-based applications correctly.
+config ANON_INODES
+ bool "Enable anonymous inode source" if EMBEDDED
+ default y
+ help
+ Anonymous inode source for pseudo-files like epoll, signalfd,
+ timerfd and eventfd.
+
+ If unsure, say Y.
+
config EPOLL
bool "Enable eventpoll support" if EMBEDDED
default y
+ depends on ANON_INODES
help
Disabling this option will cause the kernel to be built without
support for epoll family of system calls.
+config SIGNALFD
+ bool "Enable signalfd() system call" if EMBEDDED
+ depends on ANON_INODES
+ default y
+ help
+ Enable the signalfd() system call that allows to receive signals
+ on a file descriptor.
+
+ If unsure, say Y.
+
+config TIMERFD
+ bool "Enable timerfd() system call" if EMBEDDED
+ depends on ANON_INODES
+ default y
+ help
+ Enable the timerfd() system call that allows to receive timer
+ events on a file descriptor.
+
+ If unsure, say Y.
+
+config EVENTFD
+ bool "Enable eventfd() system call" if EMBEDDED
+ depends on ANON_INODES
+ default y
+ help
+ Enable the eventfd() system call that allows to receive both
+ kernel notification (ie. KAIO) or userspace notifications.
+
+ If unsure, say Y.
+
config SHMEM
bool "Use full shmem filesystem" if EMBEDDED
default y
on EMBEDDED 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 EMBEDDED
+ depends on SLUB
+ 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.
+
choice
prompt "Choose SLAB allocator"
default SLAB
bool "SLAB"
help
The regular slab allocator that is established and known to work
- well in all environments. It organizes chache hot objects in
+ well in all environments. It organizes cache hot objects in
per cpu and per node queues. SLAB is the default choice for
- slab allocator.
+ a slab allocator.
config SLUB
- depends on EXPERIMENTAL && !ARCH_USES_SLAB_PAGE_STRUCT
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
- way and has enhanced diagnostics.
+ and has enhanced diagnostics.
config SLOB
-#
-# SLOB cannot support SMP because SLAB_DESTROY_BY_RCU does not work
-# properly.
-#
- depends on EMBEDDED && !SMP && !SPARSEMEM
+ depends on EMBEDDED && !SPARSEMEM
bool "SLOB (Simple Allocator)"
help
SLOB replaces the SLAB allocator with a drastically simpler
- allocator. SLOB is more space efficient that SLAB but does not
- scale well (single lock for all operations) and is more susceptible
- to fragmentation. SLOB it is a great choice to reduce
- memory usage and code size for embedded systems.
+ allocator. SLOB is more space efficient than SLAB but does not
+ scale well (single lock for all operations) and is also highly
+ susceptible to fragmentation. SLUB can accomplish a higher object
+ density. It is usually better to use SLUB instead of SLOB.
endchoice