From f85e2cb5dbaf905e9470d3fe099b31619da431fc Mon Sep 17 00:00:00 2001
From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Date: Thu, 24 Nov 2011 17:41:54 +0800
Subject: [PATCH] KVM: introduce a table to map slot id to index in memslots
array
The operation of getting dirty log is frequent when framebuffer-based
displays are used(for example, Xwindow), so, we introduce a mapping table
to speed up id_to_memslot()
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---
include/linux/kvm_host.h | 13 +++++++------
virt/kvm/kvm_main.c | 7 ++++++-
2 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 9efdf5c703a5f..8c5c30361b0d7 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -239,6 +239,8 @@ struct kvm_irq_routing_table {};
struct kvm_memslots {
u64 generation;
struct kvm_memory_slot memslots[KVM_MEM_SLOTS_NUM];
+ /* The mapping table from slot id to the index in memslots[]. */
+ int id_to_index[KVM_MEM_SLOTS_NUM];
};
struct kvm {
@@ -341,14 +343,13 @@ static inline struct kvm_memslots *kvm_memslots(struct kvm *kvm)
static inline struct kvm_memory_slot *
id_to_memslot(struct kvm_memslots *slots, int id)
{
- int i;
+ int index = slots->id_to_index[id];
+ struct kvm_memory_slot *slot;
- for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
- if (slots->memslots[i].id == id)
- return &slots->memslots[i];
+ slot = &slots->memslots[index];
- WARN_ON(1);
- return NULL;
+ WARN_ON(slot->id != id);
+ return slot;
}
#define HPA_MSB ((sizeof(hpa_t) * 8) - 1)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 6e8eb15dd30bd..e289486edc6d9 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -446,7 +446,7 @@ static void kvm_init_memslots_id(struct kvm *kvm)
struct kvm_memslots *slots = kvm->memslots;
for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
- slots->memslots[i].id = i;
+ slots->id_to_index[i] = slots->memslots[i].id = i;
}
static struct kvm *kvm_create_vm(void)
@@ -674,8 +674,13 @@ static int cmp_memslot(const void *slot1, const void *slot2)
*/
static void sort_memslots(struct kvm_memslots *slots)
{
+ int i;
+
sort(slots->memslots, KVM_MEM_SLOTS_NUM,
sizeof(struct kvm_memory_slot), cmp_memslot, NULL);
+
+ for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
+ slots->id_to_index[slots->memslots[i].id] = i;
}
void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new)
--
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