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  1. 08 4月, 2012 4 次提交
    • T
      KVM: MMU: Improve iteration through sptes from rmap · 1e3f42f0
      由 Takuya Yoshikawa 提交于 
      Iteration using rmap_next(), the actual body is pte_list_next(), is
inefficient: every time we call it we start from checking whether rmap
holds a single spte or points to a descriptor which links more sptes.

In the case of shadow paging, this quadratic total iteration cost is a
problem.  Even for two dimensional paging, with EPT/NPT on, in which we
almost always have a single mapping, the extra checks at the end of the
iteration should be eliminated.

This patch fixes this by introducing rmap_iterator which keeps the
iteration context for the next search.  Furthermore the implementation
of rmap_next() is splitted into two functions, rmap_get_first() and
rmap_get_next(), to avoid repeatedly checking whether the rmap being
iterated on has only one spte.

Although there seemed to be only a slight change for EPT/NPT, the actual
improvement was significant: we observed that GET_DIRTY_LOG for 1GB
dirty memory became 15% faster than before.  This is probably because
the new code is easy to make branch predictions.

Note: we just remove pte_list_next() because we can think of parent_ptes
as a reverse mapping.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NAvi Kivity <avi@redhat.com>
      1e3f42f0
    • T
      KVM: MMU: Make pte_list_desc fit cache lines well · 220f773a
      由 Takuya Yoshikawa 提交于 
      We have PTE_LIST_EXT + 1 pointers in this structure and these 40/20
bytes do not fit cache lines well.  Furthermore, some allocators may
use 64/32-byte objects for the pte_list_desc cache.

This patch solves this problem by changing PTE_LIST_EXT from 4 to 3.

For shadow paging, the new size is still large enough to hold both the
kernel and process mappings for usual anonymous pages.  For file
mappings, there may be a slight change in the cache usage.

Note: with EPT/NPT we almost always have a single spte in each reverse
mapping and we will not see any change by this.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NAvi Kivity <avi@redhat.com>
      220f773a
    • T
      KVM: Avoid checking huge page mappings in get_dirty_log() · 5dc99b23
      由 Takuya Yoshikawa 提交于 
      Dropped such mappings when we enabled dirty logging and we will never
create new ones until we stop the logging.

For this we introduce a new function which can be used to write protect
a range of PT level pages: although we do not need to care about a range
of pages at this point, the following patch will need this feature to
optimize the write protection of many pages.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NAvi Kivity <avi@redhat.com>
      5dc99b23
    • T
      KVM: MMU: Split the main body of rmap_write_protect() off from others · a0ed4607
      由 Takuya Yoshikawa 提交于 
      We will use this in the following patch to implement another function
which needs to write protect pages using the rmap information.

Note that there is a small change in debug printing for large pages:
we do not differentiate them from others to avoid duplicating code.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NAvi Kivity <avi@redhat.com>
      a0ed4607
  3. 08 3月, 2012 3 次提交
  5. 05 3月, 2012 6 次提交
  7. 13 1月, 2012 1 次提交
  9. 27 12月, 2011 20 次提交
  11. 26 9月, 2011 2 次提交
  13. 24 7月, 2011 4 次提交