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Nadia Derbey 9eefe520c8 ipc: do not use a negative value to re-enable msgmni automatic recomputing ... This patch proposes an alternative to the "magical positive-versus-negative number trick" Andrew complained about last week in http://lkml.org/lkml/2008/6/24/418. This had been introduced with the patches that scale msgmni to the amount of lowmem. With these patches, msgmni has a registered notification routine that recomputes msgmni value upon memory add/remove or ipc namespace creation/ removal. When msgmni is changed from user space (i.e. value written to the proc file), that notification routine is unregistered, and the way to make it registered back is to write a negative value into the proc file. This is the "magical positive-versus-negative number trick". To fix this, a new proc file is introduced: /proc/sys/kernel/auto_msgmni. This file acts as ON/OFF for msgmni automatic recomputing. With this patch, the process is the following: 1) kernel boots in "automatic recomputing mode" /proc/sys/kernel/msgmni contains the value that has been computed (depends on lowmem) /proc/sys/kernel/automatic_msgmni contains "1" 2) echo <val> > /proc/sys/kernel/msgmni . sets msg_ctlmni to <val> . de-activates automatic recomputing (i.e. if, say, some memory is added msgmni won't be recomputed anymore) . /proc/sys/kernel/automatic_msgmni now contains "0" 3) echo "0" > /proc/sys/kernel/automatic_msgmni . de-activates msgmni automatic recomputing this has the same effect as 2) except that msg_ctlmni's value stays blocked at its current value) 3) echo "1" > /proc/sys/kernel/automatic_msgmni . recomputes msgmni's value based on the current available memory size and number of ipc namespaces . re-activates automatic recomputing for msgmni. Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net> Cc: Solofo Ramangalahy <Solofo.Ramangalahy@bull.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		17 years ago
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acpi	…
asm-alpha	clean up duplicated alloc/free_thread_info	17 years ago
asm-arm	include/asm/ptrace.h userspace headers cleanup	17 years ago
asm-avr32	clean up duplicated alloc/free_thread_info	17 years ago
asm-blackfin	include/asm/ptrace.h userspace headers cleanup	17 years ago
asm-cris	include/asm/ptrace.h userspace headers cleanup	17 years ago
asm-frv	include/asm/ptrace.h userspace headers cleanup	17 years ago
asm-generic	gpiolib: allow user-selection	17 years ago
asm-h8300	clean up duplicated alloc/free_thread_info	17 years ago
asm-ia64	clean up duplicated alloc/free_thread_info	17 years ago
asm-m32r	clean up duplicated alloc/free_thread_info	17 years ago
asm-m68k	clean up duplicated alloc/free_thread_info	17 years ago
asm-m68knommu	include/asm/ptrace.h userspace headers cleanup	17 years ago
asm-mips	gpiolib: allow user-selection	17 years ago
asm-mn10300	include/asm/ptrace.h userspace headers cleanup	17 years ago
asm-parisc	include/asm/ptrace.h userspace headers cleanup	17 years ago
asm-powerpc	include/asm/ptrace.h userspace headers cleanup	17 years ago
asm-s390	clean up duplicated alloc/free_thread_info	17 years ago
asm-sh	include/asm/ptrace.h userspace headers cleanup	17 years ago
asm-sparc	clean up duplicated alloc/free_thread_info	17 years ago
asm-sparc64	Remove asm/semaphore.h	17 years ago
asm-um	clean up duplicated alloc/free_thread_info	17 years ago
asm-v850	remove the v850 port	17 years ago
asm-x86	include/asm/ptrace.h userspace headers cleanup	17 years ago
asm-xtensa	include/asm/ptrace.h userspace headers cleanup	17 years ago
crypto	…
drm	…
keys	…
linux	ipc: do not use a negative value to re-enable msgmni automatic recomputing	17 years ago
math-emu	…
media	…
mtd	…
net	include: use get/put_unaligned_* helpers	17 years ago
pcmcia	…
rdma	…
rxrpc	…
scsi	…
sound	…
video	neofb: drop the xtimings structure	17 years ago
xen	…
Kbuild	…