• Christoph Lameter's avatar
    vmstat: use our own timer events · d1187ed2
    Christoph Lameter authored
    vmstat is currently using the cache reaper to periodically bring the
    statistics up to date.  The cache reaper does only exists in SLUB as a way to
    provide compatibility with SLAB.  This patch removes the vmstat calls from the
    slab allocators and provides its own handling.
    
    The advantage is also that we can use a different frequency for the updates.
    Refreshing vm stats is a pretty fast job so we can run this every second and
    stagger this by only one tick.  This will lead to some overlap in large
    systems.  F.e a system running at 250 HZ with 1024 processors will have 4 vm
    updates occurring at once.
    
    However, the vm stats update only accesses per node information.  It is only
    necessary to stagger the vm statistics updates per processor in each node.  Vm
    counter updates occurring on distant nodes will not cause cacheline
    contention.
    
    We could implement an alternate approach that runs the first processor on each
    node at the second and then each of the other processor on a node on a
    subsequent tick.  That may be useful to keep a large amount of the second free
    of timer activity.  Maybe the timer folks will have some feedback on this one?
    
    [jirislaby@gmail.com: add missing break]
    Cc: Arjan van de Ven <arjan@linux.intel.com>
    Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
    Signed-off-by: default avatarJiri Slaby <jirislaby@gmail.com>
    Cc: Oleg Nesterov <oleg@tv-sign.ru>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    d1187ed2
slub.c 84.8 KB