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| author | Ingo Molnar <mingo@elte.hu> | 2008-08-13 18:02:18 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-08-15 19:17:33 +0200 |
| commit | 2fdc86901d2ab30a12402b46238951d2a7891590 (patch) | |
| tree | 8f514c642a9b541ba474c68272c8a38104d8a1cd /Documentation | |
| parent | 8d6ea9674cb12b90c800dc572214bf06f6ce8340 (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 'Documentation')
0 files changed, 0 insertions, 0 deletions