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authorTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>2012-07-02 17:59:33 +0900
committerMarcelo Tosatti <mtosatti@redhat.com>2012-07-18 16:55:04 -0300
commitbcd3ef58283a471d6b65855b83f78bd39eb55391 (patch)
treed8814c9fbf17570a1cbed823b2dea7468fe9c1d9 /arch/x86/kvm/mmu.c
parentf395302e09ef783b8f82d1160510a95aa8c66dbc (diff)
downloadblackbird-op-linux-bcd3ef58283a471d6b65855b83f78bd39eb55391.tar.gz
blackbird-op-linux-bcd3ef58283a471d6b65855b83f78bd39eb55391.zip
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>
Diffstat (limited to 'arch/x86/kvm/mmu.c')
-rw-r--r--arch/x86/kvm/mmu.c28
1 files changed, 18 insertions, 10 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 58adec384489..a5d6ef785b7e 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1277,7 +1277,7 @@ static int kvm_handle_hva_range(struct kvm *kvm,
kvm_for_each_memslot(memslot, slots) {
unsigned long hva_start, hva_end;
- gfn_t gfn, gfn_end;
+ gfn_t gfn_start, gfn_end;
hva_start = max(start, memslot->userspace_addr);
hva_end = min(end, memslot->userspace_addr +
@@ -1286,19 +1286,27 @@ static int kvm_handle_hva_range(struct kvm *kvm,
continue;
/*
* {gfn(page) | page intersects with [hva_start, hva_end)} =
- * {gfn, gfn+1, ..., gfn_end-1}.
+ * {gfn_start, gfn_start+1, ..., gfn_end-1}.
*/
- gfn = hva_to_gfn_memslot(hva_start, memslot);
+ gfn_start = hva_to_gfn_memslot(hva_start, memslot);
gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot);
- for (; gfn < gfn_end; ++gfn) {
- for (j = PT_PAGE_TABLE_LEVEL;
- j < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++j) {
- unsigned long *rmapp;
+ for (j = PT_PAGE_TABLE_LEVEL;
+ j < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++j) {
+ unsigned long idx, idx_end;
+ unsigned long *rmapp;
- rmapp = __gfn_to_rmap(gfn, j, memslot);
- ret |= handler(kvm, rmapp, memslot, data);
- }
+ /*
+ * {idx(page_j) | page_j intersects with
+ * [hva_start, hva_end)} = {idx, idx+1, ..., idx_end}.
+ */
+ idx = gfn_to_index(gfn_start, memslot->base_gfn, j);
+ idx_end = gfn_to_index(gfn_end - 1, memslot->base_gfn, j);
+
+ rmapp = __gfn_to_rmap(gfn_start, j, memslot);
+
+ for (; idx <= idx_end; ++idx)
+ ret |= handler(kvm, rmapp++, memslot, data);
}
}
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