From: Li RongQing <lirongqing@xxxxxxxxx>
Use call_rcu() instead of costly synchronize_srcu_expedited(), this
can reduce the VM bootup time, and reduce VM migration downtime
Signed-off-by: lizhaoxin <lizhaoxin04@xxxxxxxxx>
Signed-off-by: Li RongQing <lirongqing@xxxxxxxxx>
---
include/linux/kvm_host.h | 1 +
virt/kvm/kvm_main.c | 11 +++++++++--
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 291d49b..e772704 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -203,6 +203,7 @@ struct kvm_io_range {
#define NR_IOBUS_DEVS 1000
struct kvm_io_bus {
+ struct rcu_head rcu;
int dev_count;
int ioeventfd_count;
struct kvm_io_range range[];
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2e591cc..af730a5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -5865,6 +5865,13 @@ int kvm_io_bus_read(struct kvm_vcpu *vcpu, enum kvm_bus bus_idx, gpa_t addr,
return r < 0 ? r : 0;
}
+static void free_kvm_io_bus(struct rcu_head *rcu)
+{
+ struct kvm_io_bus *bus = container_of(rcu, struct kvm_io_bus, rcu);
+
+ kfree(bus);
+}
+
int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
int len, struct kvm_io_device *dev)
{
@@ -5903,8 +5910,8 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
memcpy(new_bus->range + i + 1, bus->range + i,
(bus->dev_count - i) * sizeof(struct kvm_io_range));
rcu_assign_pointer(kvm->buses[bus_idx], new_bus);
- synchronize_srcu_expedited(&kvm->srcu);
- kfree(bus);
+
+ call_srcu(&kvm->srcu, &bus->rcu, free_kvm_io_bus);
return 0;
}
--
2.9.4
