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  • Frank Pavlic's avatar
    [PATCH] s390: qdio V=V pass-through · 8129ee16
    Frank Pavlic authored
    
    
    New feature V=V qdio pass-through.
    
    QDIO and HiperSockets processing in z/VM V=V guest environments (as well as
    V=R with z/VM running in LPAR mode) requires shadowing of all QDIO
    architecture queue elements.  Especially the shadowing of SBALs and SLSBs
    structures in the hypervisor, and the need to issue SIGA SYNC operations to
    observe state changes, eventually causes significant CPU processing overhead
    in the hypervisor.
    
    The QDIO pass-through support for V=V guests avoids the shadowing of SBALs and
    SLSBs.  This significantly reduces the hypervisor overhead for QDIO based I/O.
    
    Signed-off-by: default avatarFrank Pavlic <pavlic@de.ibm.com>
    Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    8129ee16