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  • Christoph Lameter's avatar
    [PATCH] Swap Migration V5: sys_migrate_pages interface · 39743889
    Christoph Lameter authored
    
    
    sys_migrate_pages implementation using swap based page migration
    
    This is the original API proposed by Ray Bryant in his posts during the first
    half of 2005 on linux-mm@kvack.org and linux-kernel@vger.kernel.org.
    
    The intent of sys_migrate is to migrate memory of a process.  A process may
    have migrated to another node.  Memory was allocated optimally for the prior
    context.  sys_migrate_pages allows to shift the memory to the new node.
    
    sys_migrate_pages is also useful if the processes available memory nodes have
    changed through cpuset operations to manually move the processes memory.  Paul
    Jackson is working on an automated mechanism that will allow an automatic
    migration if the cpuset of a process is changed.  However, a user may decide
    to manually control the migration.
    
    This implementation is put into the policy layer since it uses concepts and
    functions that are also needed for mbind and friends.  The patch also provides
    a do_migrate_pages function that may be useful for cpusets to automatically
    move memory.  sys_migrate_pages does not modify policies in contrast to Ray's
    implementation.
    
    The current code here is based on the swap based page migration capability and
    thus is not able to preserve the physical layout relative to it containing
    nodeset (which may be a cpuset).  When direct page migration becomes available
    then the implementation needs to be changed to do a isomorphic move of pages
    between different nodesets.  The current implementation simply evicts all
    pages in source nodeset that are not in the target nodeset.
    
    Patch supports ia64, i386 and x86_64.
    
    Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    39743889