• Glauber Costa's avatar
    memcg: reduce the size of struct memcg 244-fold. · 45cf7ebd
    Glauber Costa authored
    In order to maintain all the memcg bookkeeping, we need per-node
    descriptors, which will in turn contain a per-zone descriptor.
    
    Because we want to statically allocate those, this array ends up being
    very big.  Part of the reason is that we allocate something large enough
    to hold MAX_NUMNODES, the compile time constant that holds the maximum
    number of nodes we would ever consider.
    
    However, we can do better in some cases if the firmware help us.  This
    is true for modern x86 machines; coincidentally one of the architectures
    in which MAX_NUMNODES tends to be very big.
    
    By using the firmware-provided maximum number of nodes instead of
    MAX_NUMNODES, we can reduce the memory footprint of struct memcg
    considerably.  In the extreme case in which we have only one node, this
    reduces the size of the structure from ~ 64k to ~2k.  This is
    particularly important because it means that we will no longer resort to
    the vmalloc area for the struct memcg on defconfigs.  We also have
    enough room for an extra node and still be outside vmalloc.
    
    One also has to keep in mind that with the industry's ability to fit
    more processors in a die as fast as the FED prints money, a nodes = 2
    configuration is already respectably big.
    
    [akpm@linux-foundation.org: add check for invalid nid, remove inline]
    Signed-off-by: default avatarGlauber Costa <glommer@parallels.com>
    Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
    Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    Cc: Johannes Weiner <hannes@cmpxchg.org>
    Reviewed-by: default avatarGreg Thelen <gthelen@google.com>
    Cc: Hugh Dickins <hughd@google.com>
    Cc: Ying Han <yinghan@google.com>
    Cc: Mel Gorman <mgorman@suse.de>
    Cc: Rik van Riel <riel@redhat.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    45cf7ebd
memcontrol.c 180 KB