• Roger Pau Monne's avatar
    xen-blkback: implement LRU mechanism for persistent grants · 3f3aad5e
    Roger Pau Monne authored
    This mechanism allows blkback to change the number of grants
    persistently mapped at run time.
    
    The algorithm uses a simple LRU mechanism that removes (if needed) the
    persistent grants that have not been used since the last LRU run, or
    if all grants have been used it removes the first grants in the list
    (that are not in use).
    
    The algorithm allows the user to change the maximum number of
    persistent grants, by changing max_persistent_grants in sysfs.
    
    Since we are storing the persistent grants used inside the request
    struct (to be able to mark them as "unused" when unmapping), we no
    longer need the bitmap (unmap_seg).
    Signed-off-by: default avatarRoger Pau Monné <roger.pau@citrix.com>
    Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    Cc: xen-devel@lists.xen.org
    Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    3f3aad5e
xenbus.c 19.5 KB