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Andi Kleen wrote:
> That's just an inadequate data structure. It does an linear search of the
> VMAs and you probably have a lot of them. Before you add kludges like this
> better fix the data structure for fast free space lookup.
If you mean the code in arch_get_unmapped_area(), yes, this needs
fixing. In fact, Ingo has already a patch which brings back the
performance of thread creation to what we had back in September/October.
> In some vendor kernels it's already in /proc/pid/mapped_base, but that is
> quite costly to change. That would probably give you the best of both, Just
> set it to a low value for the thread stacks and then reset it to the default.
>
> I guess that would be the better solution for your stacks.
Are you sure this is the best solution? It means the mmap regions for
restricted 31/32 bit addresses and that for the normal, unrestricted
mapping is continuous. This removes a lot of freedom in deciding where
the unrestricted mappings are best located and it would make programs
using threads have a very different memory layout. Not that it should
make any difference; but I can here /them/ already scream that this
breaks applications.
My kernel-uninformed opinion would be to keep the settings separate.
Oh, and please rename MAP_32BIT to MAP_31BIT. This will save nerves on
all sides.
- --
- --------------. ,-. 444 Castro Street
Ulrich Drepper \ ,-----------------' \ Mountain View, CA 94041 USA
Red Hat `--' drepper at redhat.com `---------------------------
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This archive was generated by hypermail 2b29 : Thu May 15 2003 - 22:00:31 EST