• Andrew Morton's avatar
    [PATCH] Use address hint in mmap for search · ed205520
    Andrew Morton authored
    From: Andi Kleen <ak@suse.de>
    
    When the user gave an address hint in mmap use it as starting point for the
    search for !MAP_FIXED.
    
    Currently it is only checked directly and when already used the free area
    cache is used as starting point.  With this change you can use mmap(4096,
    ....) to e.g.  get the lowest free address in your address space, which is
    sometimes useful.  For example on x86-64 glibc wants to preferably allocate
    thread local data in the first 4GB but use higher addresses when this is
    not possible.
    
    This can be a bit more costly in CPU time because it may have to skip over
    more VMAs, but gives better semantics for most cases.  Most programs pass
    NULL as hint anyways so it won't make any difference for them.
    
    I did it for the generic mmap and for x86-64 for now.  Also minor white
    space fixes for x86-64.
    ed205520
mmap.c 36.3 KB