• Robin Holt's avatar
    [IA64] Percpu quicklist for combined allocator for pgd/pmd/pte. · fde740e4
    Robin Holt authored
    This patch introduces using the quicklists for pgd, pmd, and pte levels
    by combining the alloc and free functions into a common set of routines.
    This greatly simplifies the reading of this header file.
    
    This patch is simple but necessary for large numa configurations.
    It simply ensures that only pages from the local node are added to a
    cpus quicklist.  This prevents the trapping of pages on a remote nodes
    quicklist by starting a process, touching a large number of pages to
    fill pmd and pte entries, migrating to another node, and then unmapping
    or exiting.  With those conditions, the pages get trapped and if the
    machine has more than 100 nodes of the same size, the calculation of
    the pgtable high water mark will be larger than any single node so page
    table cache flushing will never occur.
    
    I ran lmbench lat_proc fork and lat_proc exec on a zx1 with and without
    this patch and did not notice any change.
    
    On an sn2 machine, there was a slight improvement which is possibly
    due to pages from other nodes trapped on the test node before starting
    the run.  I did not investigate further.
    
    This patch shrinks the quicklist based upon free memory on the node
    instead of the high/low water marks.  I have written it to enable
    preemption periodically and recalculate the amount to shrink every time
    we have freed enough pages that the quicklist size should have grown.
    I rescan the nodes zones each pass because other processess may be
    draining node memory at the same time as we are adding.
    Signed-off-by: default avatarRobin Holt <holt@sgi.com>
    Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
    fde740e4
discontig.c 21.2 KB