Messages in this thread | | | Date | Tue, 4 Dec 2001 14:42:28 -0200 (BRST) | From | Rik van Riel <> | Subject | Re[2]: your mail on mmap() to the kernel list |
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On Tue, 4 Dec 2001, Peter Zaitsev wrote: > Tuesday, December 04, 2001, 5:15:49 PM, you wrote:
> AA> You can fix the problem in userspace by using a meaningful 'addr' as > AA> hint to mmap(2), or by using MAP_FIXED from userspace, then the kernel > AA> won't waste time searching the first available mapping over > AA> TASK_UNMAPPED_BASE.
> Well. Really you can't do this, because you can not really track all of > the mappings in user program as glibc and probably other libraries > use mmap for their purposes.
There's no reason we couldn't do this hint in kernel space.
In arch_get_unmapped_area we can simply keep track of the lowest address where we found free space, while on munmap() we can adjust this hint if needed.
OTOH, I doubt it would help real-world workloads where the application maps and unmaps areas of different sizes and actually does something with the memory instead of just mapping and unmapping it ;)))
kind regards,
Rik -- Shortwave goes a long way: irc.starchat.net #swl
http://www.surriel.com/ http://distro.conectiva.com/
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