1. 10 Aug, 2017 39 commits
  2. 08 Aug, 2017 1 commit
    • Michael Ellerman's avatar
      powerpc/mm/hash64: Make vmalloc 56T on hash · 21a0e8c1
      Michael Ellerman authored
      On 64-bit book3s, with the hash MMU, we currently define the kernel
      virtual space (vmalloc, ioremap etc.), to be 16T in size. This is a
      leftover from pre v3.7 when our user VM was also 16T.
      
      Of that 16T we split it 50/50, with half used for PCI IO and ioremap
      and the other 8T for vmalloc.
      
      We never bothered to make it any bigger because 8T of vmalloc ought to
      be enough for anybody. But it turns out that's not true, the per cpu
      allocator wants large amounts of vmalloc space, not to make large
      allocations, but to allow a large stride between allocations, because
      we use pcpu_embed_first_chunk().
      
      With a bit of juggling we can increase the entire kernel virtual space
      to 64T. The only real complication is the check of the address in the
      SLB miss handler, see the comment in the code.
      
      Although we could continue to split virtual space 50/50 as we do now,
      no one seems to be running out of PCI IO or ioremap space. So instead
      keep that as 8T, and use the remaining 56T for vmalloc.
      
      In future we should be able to increase the kernel virtual space to
      512T, the code already supports that, it just needs testing on older
      hardware.
      Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      Reviewed-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
      21a0e8c1