memory.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-)
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 v1->v2:
- create a VMChangeStateHandler in memory.c to reduce the coupling [Paolo]
Signed-off-by: Jay Zhou <jianjay.zhou@huawei.com>
---
memory.c | 27 ++++++++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)
diff --git a/memory.c b/memory.c
index a7bc70a..4c22b7e 100644
--- a/memory.c
+++ b/memory.c
@@ -2357,8 +2357,14 @@ 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);
+ }
+
global_dirty_log = true;
MEMORY_LISTENER_CALL_GLOBAL(log_global_start, Forward);
@@ -2369,7 +2375,7 @@ 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 +2387,25 @@ 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();
+ }
+}
+
+void memory_global_dirty_log_stop(void)
+{
+ if (!runstate_is_running()) {
+ 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)
{
--
1.8.3.1
On 27/07/2017 04:36, Jay Zhou wrote:
> 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 v1->v2:
> - create a VMChangeStateHandler in memory.c to reduce the coupling [Paolo]
>
> Signed-off-by: Jay Zhou <jianjay.zhou@huawei.com>
memory_vm_change_state_handler should delete the handler.
Apart from that, because there is no protection against nested
invocations of memory_global_dirty_log_start/stop, a little more work is
needed.
> ---
> memory.c | 27 ++++++++++++++++++++++++++-
> 1 file changed, 26 insertions(+), 1 deletion(-)
>
> diff --git a/memory.c b/memory.c
> index a7bc70a..4c22b7e 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -2357,8 +2357,14 @@ 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);
This should also NULL vmstate_change, so that you can detect the case
where the handler is already installed.
> + }
> +
> global_dirty_log = true;
>
> MEMORY_LISTENER_CALL_GLOBAL(log_global_start, Forward);
> @@ -2369,7 +2375,7 @@ 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 +2387,25 @@ 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();
Because this will delete the handler, it should also NULL vmstate_change.
> + }
> +}
> +
> +void memory_global_dirty_log_stop(void)
> +{
> + if (!runstate_is_running()) {
> + vmstate_change = qemu_add_vm_change_state_handler(
> + memory_vm_change_state_handler, NULL);
And this needs to exit immediately if you have an installed handler.
Thanks,
Paolo
> + return;
> + }
> +
> + memory_global_dirty_log_do_stop();
> +}
> +
> static void listener_add_address_space(MemoryListener *listener,
> AddressSpace *as)
> {
>
Hi Paolo,
On 2017/7/27 22:15, Paolo Bonzini wrote:
> On 27/07/2017 04:36, Jay Zhou wrote:
>> 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 v1->v2:
>> - create a VMChangeStateHandler in memory.c to reduce the coupling [Paolo]
>>
>> Signed-off-by: Jay Zhou <jianjay.zhou@huawei.com>
>
> memory_vm_change_state_handler should delete the handler.
>
> Apart from that, because there is no protection against nested
> invocations of memory_global_dirty_log_start/stop, a little more work is
> needed.
Thank for your patience and pointing everything out, I will fix all of them.
Jay
>> ---
>> memory.c | 27 ++++++++++++++++++++++++++-
>> 1 file changed, 26 insertions(+), 1 deletion(-)
>>
>> diff --git a/memory.c b/memory.c
>> index a7bc70a..4c22b7e 100644
>> --- a/memory.c
>> +++ b/memory.c
>> @@ -2357,8 +2357,14 @@ 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);
>
> This should also NULL vmstate_change, so that you can detect the case
> where the handler is already installed.
>
>> + }
>> +
>> global_dirty_log = true;
>>
>> MEMORY_LISTENER_CALL_GLOBAL(log_global_start, Forward);
>> @@ -2369,7 +2375,7 @@ 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 +2387,25 @@ 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();
>
> Because this will delete the handler, it should also NULL vmstate_change.
>
>> + }
>> +}
>> +
>> +void memory_global_dirty_log_stop(void)
>> +{
>> + if (!runstate_is_running()) {
>> + vmstate_change = qemu_add_vm_change_state_handler(
>> + memory_vm_change_state_handler, NULL);
>
> And this needs to exit immediately if you have an installed handler.
>
> Thanks,
>
> Paolo
>
>> + return;
>> + }
>> +
>> + memory_global_dirty_log_do_stop();
>> +}
>> +
>> static void listener_add_address_space(MemoryListener *listener,
>> AddressSpace *as)
>> {
>>
>
>
> .
>
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