From: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Date: Mon, 2 Jul 2012 08:59:33 +0000 (+0900)
Subject: KVM: MMU: Avoid handling same rmap_pde in kvm_handle_hva_range()
X-Git-Tag: omap-for-v3.7-rc1/fixes-cpufreq-signed~15^2~101^2~17
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bcd3ef58283a471d6b65855b83f78bd39eb55391;p=pandora-kernel.git

KVM: MMU: Avoid handling same rmap_pde in kvm_handle_hva_range()

When we invalidate a THP page, we call the handler with the same
rmap_pde argument 512 times in the following loop:

  for each guest page in the range
    for each level
      unmap using rmap

This patch avoids these extra handler calls by changing the loop order
like this:

  for each level
    for each rmap in the range
      unmap using rmap

With the preceding patches in the patch series, this made THP page
invalidation more than 5 times faster on our x86 host: the host became
more responsive during swapping the guest's memory as a result.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
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