Re: [Qemu-devel] [PATCH 11/12] ram: iterate phase

[Juan Quintela <quintela@redhat.com>]

Igor Mitsyanko <i.mitsyanko@gmail.com> wrote:
> On 6/28/2012 11:22 PM, Juan Quintela wrote:
>> We only need to synchronize the bitmap when the number of dirty pages is low.
>> Not every time that we call the function.
>>
>> Signed-off-by: Juan Quintela <quintela@redhat.com>
>> ---
>>   arch_init.c |    9 ++++++---
>>   1 file changed, 6 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch_init.c b/arch_init.c
>> index fe843a7..8299c15 100644
>> --- a/arch_init.c
>> +++ b/arch_init.c
>> @@ -348,8 +348,6 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
>>       int i;
>>       uint64_t expected_time;
>>
>> -    memory_global_sync_dirty_bitmap(get_system_memory());
>> -
>>       bytes_transferred_last = bytes_transferred;
>>       bwidth = qemu_get_clock_ns(rt_clock);
>>
>> @@ -397,7 +395,12 @@ static int ram_save_iterate(QEMUFile *f, void *opaque)
>>       DPRINTF("ram_save_live: expected(%ld) <= max(%ld)?\n", expected_time,
>>               migrate_max_downtime());
>>
>> -    return expected_time <= migrate_max_downtime();
>> +    if (expected_time <= migrate_max_downtime()) {
>> +        memory_global_sync_dirty_bitmap(get_system_memory());
>> +
>> +        return expected_time <= migrate_max_downtime();
>
> Shouldn't expected_time be recalculated after
> memory_global_sync_dirty_bitmap()?

It "depends" only of the network speed,
memory_global_sync_dirty_bitmap() should be really fast (notice that
with lots of memory this couldn't be true).

Later, Juan.