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authorJay Zhou <jianjay.zhou@huawei.com>2017-07-28 18:28:53 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2017-08-01 17:27:33 +0200
commit1931076077254a2886daa7c830c7838ebd1f81ef (patch)
tree79cd172b4130defaf256155b99b8950234336408
parent8bfce83a3b50d45b7107a50a6cd61d5304a925a2 (diff)
downloadqemu-arm-1931076077254a2886daa7c830c7838ebd1f81ef.tar.gz
migration: optimize the downtime
Qemu_savevm_state_cleanup takes about 300ms in my ram migration tests with a 8U24G vm(20G is really occupied), the main cost comes from KVM_SET_USER_MEMORY_REGION ioctl when mem.memory_size = 0 in kvm_set_user_memory_region. In kmod, the main cost is kvm_zap_obsolete_pages, which traverses the active_mmu_pages list to zap the unsync sptes. It can be optimized by delaying memory_global_dirty_log_stop to the next vm_start. Changes v2->v3: - NULL VMChangeStateHandler if it is deleted and protect the scenario of nested invocations of memory_global_dirty_log_start/stop [Paolo] Changes v1->v2: - create a VMChangeStateHandler in memory.c to reduce the coupling [Paolo] Signed-off-by: Jay Zhou <jianjay.zhou@huawei.com> Message-Id: <1501237733-2736-1-git-send-email-jianjay.zhou@huawei.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--memory.c36
1 files changed, 35 insertions, 1 deletions
diff --git a/memory.c b/memory.c
index a7bc70aac1..c0adc35410 100644
--- a/memory.c
+++ b/memory.c
@@ -2357,8 +2357,15 @@ void memory_global_dirty_log_sync(void)
}
}
+static VMChangeStateEntry *vmstate_change;
+
void memory_global_dirty_log_start(void)
{
+ if (vmstate_change) {
+ qemu_del_vm_change_state_handler(vmstate_change);
+ vmstate_change = NULL;
+ }
+
global_dirty_log = true;
MEMORY_LISTENER_CALL_GLOBAL(log_global_start, Forward);
@@ -2369,7 +2376,7 @@ void memory_global_dirty_log_start(void)
memory_region_transaction_commit();
}
-void memory_global_dirty_log_stop(void)
+static void memory_global_dirty_log_do_stop(void)
{
global_dirty_log = false;
@@ -2381,6 +2388,33 @@ void memory_global_dirty_log_stop(void)
MEMORY_LISTENER_CALL_GLOBAL(log_global_stop, Reverse);
}
+static void memory_vm_change_state_handler(void *opaque, int running,
+ RunState state)
+{
+ if (running) {
+ memory_global_dirty_log_do_stop();
+
+ if (vmstate_change) {
+ qemu_del_vm_change_state_handler(vmstate_change);
+ vmstate_change = NULL;
+ }
+ }
+}
+
+void memory_global_dirty_log_stop(void)
+{
+ if (!runstate_is_running()) {
+ if (vmstate_change) {
+ return;
+ }
+ vmstate_change = qemu_add_vm_change_state_handler(
+ memory_vm_change_state_handler, NULL);
+ return;
+ }
+
+ memory_global_dirty_log_do_stop();
+}
+
static void listener_add_address_space(MemoryListener *listener,
AddressSpace *as)
{