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David Miller 419ca3f135 lockdep: fix combinatorial explosion in lock subgraph traversal ... When we traverse the graph, either forwards or backwards, we are interested in whether a certain property exists somewhere in a node reachable in the graph. Therefore it is never necessary to traverse through a node more than once to get a correct answer to the given query. Take advantage of this property using a global ID counter so that we need not clear all the markers in all the lock_class entries before doing a traversal. A new ID is choosen when we start to traverse, and we continue through a lock_class only if it's ID hasn't been marked with the new value yet. This short-circuiting is essential especially for high CPU count systems. The scheduler has a runqueue per cpu, and needs to take two runqueue locks at a time, which leads to long chains of backwards and forwards subgraphs from these runqueue lock nodes. Without the short-circuit implemented here, a graph traversal on a runqueue lock can take up to (1 << (N - 1)) checks on a system with N cpus. For anything more than 16 cpus or so, lockdep will eventually bring the machine to a complete standstill. Signed-off-by: David S. Miller <davem@davemloft.net> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>		17 years ago
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acpi	PCI: disable ASPM per ACPI FADT setting	17 years ago
asm-alpha	[PATCH] kill altroot	17 years ago
asm-arm	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6	17 years ago
asm-avr32	Merge commit 'upstream/master'	17 years ago
asm-blackfin	[PATCH] kill altroot	17 years ago
asm-cris	Merge branch 'linus' into core/generic-dma-coherent	17 years ago
asm-frv	[PATCH] kill altroot	17 years ago
asm-generic	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6	17 years ago
asm-h8300	[PATCH] kill altroot	17 years ago
asm-ia64	[PATCH] kill altroot	17 years ago
asm-m32r	[PATCH] kill altroot	17 years ago
asm-m68k	[PATCH] kill altroot	17 years ago
asm-m68knommu	[PATCH] kill altroot	17 years ago
asm-mips	[PATCH] kill altroot	17 years ago
asm-mn10300	[PATCH] kill altroot	17 years ago
asm-parisc	[PATCH] kill altroot	17 years ago
asm-powerpc	powerpc/mm: Implement _PAGE_SPECIAL & pte_special() for 64-bit	17 years ago
asm-s390	KVM: s390: Fix instruction naming for lctlg	17 years ago
asm-sh	Merge branch 'linus' into core/generic-dma-coherent	17 years ago
asm-um	[PATCH] kill altroot	17 years ago
asm-x86	Merge branch 'linus' into core/generic-dma-coherent	17 years ago
asm-xtensa	[PATCH] kill altroot	17 years ago
crypto	…
drm	…
keys	…
linux	lockdep: fix combinatorial explosion in lock subgraph traversal	17 years ago
math-emu	…
media	V4L/DVB (8525): fix a few assorted spelling mistakes.	17 years ago
mtd	Merge branch 'linux-next' of git://git.infradead.org/~dedekind/ubi-2.6	17 years ago
net	missing bits of net-namespace / sysctl	17 years ago
pcmcia	…
rdma	dma-mapping: add the device argument to dma_mapping_error()	17 years ago
rxrpc	…
scsi	[SCSI] extend the last_sector_bug flag to cover more sectors	17 years ago
sound	…
video	include/video/atmel_lcdc.h must #include <linux/workqueue.h>	17 years ago
xen	…
Kbuild	kbuild: only one call for include/ in make headers_*	17 years ago