• Jes Sorensen's avatar
    [PATCH] ia64 uncached alloc · f14f75b8
    Jes Sorensen authored
    This patch contains the ia64 uncached page allocator and the generic
    allocator (genalloc).  The uncached allocator was formerly part of the SN2
    mspec driver but there are several other users of it so it has been split
    off from the driver.
    The generic allocator can be used by device driver to manage special memory
    etc.  The generic allocator is based on the allocator from the sym53c8xx_2
    Various users on ia64 needs uncached memory.  The SGI SN architecture requires
    it for inter-partition communication between partitions within a large NUMA
    cluster.  The specific user for this is the XPC code.  Another application is
    large MPI style applications which use it for synchronization, on SN this can
    be done using special 'fetchop' operations but it also benefits non SN
    hardware which may use regular uncached memory for this purpose.  Performance
    of doing this through uncached vs cached memory is pretty substantial.  This
    is handled by the mspec driver which I will push out in a seperate patch.
    Rather than creating a specific allocator for just uncached memory I came up
    with genalloc which is a generic purpose allocator that can be used by device
    drivers and other subsystems as they please.  For instance to handle onboard
    device memory.  It was derived from the sym53c7xx_2 driver's allocator which
    is also an example of a potential user (I am refraining from modifying sym2
    right now as it seems to have been under fairly heavy development recently).
    On ia64 memory has various properties within a granule, ie.  it isn't safe to
    access memory as uncached within the same granule as currently has memory
    accessed in cached mode.  The regular system therefore doesn't utilize memory
    in the lower granules which is mixed in with device PAL code etc.  The
    uncached driver walks the EFI memmap and pulls out the spill uncached pages
    and sticks them into the uncached pool.  Only after these chunks have been
    utilized, will it start converting regular cached memory into uncached memory.
    Hence the reason for the EFI related code additions.
    Signed-off-by: default avatarJes Sorensen <jes@wildopensource.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
Makefile 1.26 KB