path: root/kernel/capability.c
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authorIngo Molnar <mingo@elte.hu>2008-08-13 18:02:18 +0200
committerIngo Molnar <mingo@elte.hu>2008-08-15 19:17:33 +0200
commit2fdc86901d2ab30a12402b46238951d2a7891590 (patch)
tree8f514c642a9b541ba474c68272c8a38104d8a1cd /kernel/capability.c
parent8d6ea9674cb12b90c800dc572214bf06f6ce8340 (diff)
x86: add MAP_STACK mmap flag
as per this discussion: http://lkml.org/lkml/2008/8/12/423 Pardo reported that 64-bit threaded apps, if their stacks exceed the combined size of ~4GB, slow down drastically in pthread_create() - because glibc uses MAP_32BIT to allocate the stacks. The use of MAP_32BIT is a legacy hack - to speed up context switching on certain early model 64-bit P4 CPUs. So introduce a new flag to be used by glibc instead, to not constrain 64-bit apps like this. glibc can switch to this new flag straight away - it will be ignored by the kernel. If those old CPUs ever matter to anyone, support for it can be implemented. Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Ulrich Drepper <drepper@gmail.com>
Diffstat (limited to 'kernel/capability.c')
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