1. 22 6月, 2005 1 次提交
    • J
      [PATCH] ia64 uncached alloc · f14f75b8
      Jes Sorensen 提交于
      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
      driver.
      
      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: NJes Sorensen <jes@wildopensource.com>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      f14f75b8