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.
Note: in the new code we could not use trace_kvm_age_page(), so we just
dropped the point from kvm_handle_hva_range().
Signed-off-by: Takuya Yoshikawa <[email protected]>
---
arch/x86/kvm/mmu.c | 39 ++++++++++++++++++++-------------------
1 files changed, 20 insertions(+), 19 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 306711a..462becb 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1192,16 +1192,15 @@ static int kvm_handle_hva_range(struct kvm *kvm,
unsigned long data))
{
int j;
- int ret;
- int retval = 0;
+ int ret = 0;
struct kvm_memslots *slots;
struct kvm_memory_slot *memslot;
slots = kvm_memslots(kvm);
kvm_for_each_memslot(memslot, slots) {
- gfn_t gfn;
unsigned long hva_start, hva_end;
+ gfn_t gfn_start, gfn_end;
hva_start = max(start, memslot->userspace_addr);
hva_end = min(end, memslot->userspace_addr +
@@ -1209,25 +1208,27 @@ static int kvm_handle_hva_range(struct kvm *kvm,
if (hva_start >= hva_end)
continue;
- for (gfn = hva_to_gfn_memslot(hva_start, memslot);
- gfn < hva_to_gfn_memslot(hva_end, memslot); gfn++) {
- ret = 0;
+ gfn_start = hva_to_gfn_memslot(hva_start, memslot);
+ gfn_end = hva_to_gfn_memslot(hva_end, memslot);
- 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, data);
- }
- trace_kvm_age_page(memslot->userspace_addr +
- (gfn - memslot->base_gfn) * PAGE_SIZE,
- memslot, ret);
- retval |= ret;
+ idx = gfn_to_index(gfn_start, memslot->base_gfn, j);
+ idx_end = gfn_to_index(gfn_end, memslot->base_gfn, j);
+
+ rmapp = __gfn_to_rmap(gfn_start, j, memslot);
+
+ /* Handle the first one even if idx == idx_end. */
+ do {
+ ret |= handler(kvm, rmapp++, data);
+ } while (++idx < idx_end);
}
}
- return retval;
+ return ret;
}
static int kvm_handle_hva(struct kvm *kvm, unsigned long hva,
--
1.7.5.4
--
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