[Qemu-devel] Re: [PATCH 1/3] stop dirty tracking just at the end of migration

[Glauber Costa]

On Tue, Mar 31, 2009 at 10:04:52PM +0300, Yaniv Kamay wrote:
> We need to update dirty map before ram_save_block() loop.
>From what I understand, this is needed in kvm only.
This patch applies to qemu.

>
> Glauber Costa wrote:
>> If there is still work to do, it is not safe to assume we
>> can end the dirty tracking. Specifically, kvm can update the dirty
>> tracking log inside ram_save_block(), leaving pages still out of sync
>> if we go with the current code.
>>
>> Based on a patch by Yaniv Kamay
>>
>> Signed-off-by: Glauber Costa <address@hidden>
>> CC: Yaniv Kamay <address@hidden>
>> CC: Dor Laor <address@hidden>
>> ---
>>  vl.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/vl.c b/vl.c
>> index 5e6c621..1626f8a 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -3249,10 +3249,10 @@ static int ram_save_live(QEMUFile *f, int stage, 
>> void *opaque)
>>      /* try transferring iterative blocks of memory */
>>       if (stage == 3) {
>> -        cpu_physical_memory_set_dirty_tracking(0);
>>           /* flush all remaining blocks regardless of rate limiting */
>>          while (ram_save_block(f) != 0);
>> +        cpu_physical_memory_set_dirty_tracking(0);
>>      }
>>       qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
>>   
>