![Ingo Molnar](/assets/img/avatar_default.png)
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> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
21 lines
776 B
C
21 lines
776 B
C
#ifndef _ASM_X86_MMAN_H
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#define _ASM_X86_MMAN_H
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#include <asm-generic/mman.h>
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#define MAP_32BIT 0x40 /* only give out 32bit addresses */
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#define MAP_GROWSDOWN 0x0100 /* stack-like segment */
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#define MAP_DENYWRITE 0x0800 /* ETXTBSY */
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#define MAP_EXECUTABLE 0x1000 /* mark it as an executable */
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#define MAP_LOCKED 0x2000 /* pages are locked */
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#define MAP_NORESERVE 0x4000 /* don't check for reservations */
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#define MAP_POPULATE 0x8000 /* populate (prefault) pagetables */
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#define MAP_NONBLOCK 0x10000 /* do not block on IO */
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#define MAP_STACK 0x20000 /* give out an address that is best suited for process/thread stacks */
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#define MCL_CURRENT 1 /* lock all current mappings */
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#define MCL_FUTURE 2 /* lock all future mappings */
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#endif /* _ASM_X86_MMAN_H */
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