Re: [Qemu-devel] [PATCH COLO-Frame v11 16/39] ram/COLO: Record the dirty pages that SVM received

[Hailiang Zhang <zhang.zhanghailiang@huawei.com>]

On 2015/12/2 3:36, Dr. David Alan Gilbert wrote:
> * zhanghailiang (zhang.zhanghailiang@huawei.com) wrote:
>> We record the address of the dirty pages that received,
>> it will help flushing pages that cached into SVM.
>> We record them by re-using migration dirty bitmap.
>>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>> ---
>> v11:
>> - Split a new helper function from original
>>    host_from_stream_offset() (Dave's suggestion)
>> - Only do recording work in this patch
>> v10:
>> - New patch split from v9's patch 13
>> - Rebase to master to use 'migration_bitmap_rcu'
>> ---
>>   migration/ram.c | 30 ++++++++++++++++++++++++++++++
>>   1 file changed, 30 insertions(+)
>>
>> diff --git a/migration/ram.c b/migration/ram.c
>> index 9d946a1..da6bbd6 100644
>> --- a/migration/ram.c
>> +++ b/migration/ram.c
>> @@ -2153,6 +2153,7 @@ static inline RAMBlock *ram_block_from_stream(QEMUFile *f,
>>
>>           return block;
>>       }
>> +
>>       len = qemu_get_byte(f);
>>       qemu_get_buffer(f, (uint8_t *)id, len);
>>       id[len] = 0;
>
> That blank should probably go, but other than that:
>

I will remove it, thanks.

> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>
> Dave
>
>> @@ -2179,10 +2180,23 @@ static inline void *host_from_ram_block_offset(RAMBlock *block,
>>   static inline void *colo_cache_from_block_offset(RAMBlock *block,
>>                                                    ram_addr_t offset)
>>   {
>> +    unsigned long *bitmap;
>> +    long k;
>> +
>>       if (!block) {
>>           return NULL;
>>       }
>>
>> +    k = (block->mr->ram_addr + offset) >> TARGET_PAGE_BITS;
>> +    bitmap = atomic_rcu_read(&migration_bitmap_rcu)->bmap;
>> +    /*
>> +    * During colo checkpoint, we need bitmap of these migrated pages.
>> +    * It help us to decide which pages in ram cache should be flushed
>> +    * into VM's RAM later.
>> +    */
>> +    if (!test_and_set_bit(k, bitmap)) {
>> +        migration_dirty_pages++;
>> +    }
>>       return block->colo_cache + offset;
>>   }
>>
>> @@ -2573,6 +2587,7 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id)
>>   int colo_init_ram_cache(void)
>>   {
>>       RAMBlock *block;
>> +    int64_t ram_cache_pages = last_ram_offset() >> TARGET_PAGE_BITS;
>>
>>       rcu_read_lock();
>>       QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
>> @@ -2587,6 +2602,15 @@ int colo_init_ram_cache(void)
>>       }
>>       rcu_read_unlock();
>>       ram_cache_enable = true;
>> +    /*
>> +    * Record the dirty pages that sent by PVM, we use this dirty bitmap together
>> +    * with to decide which page in cache should be flushed into SVM's RAM. Here
>> +    * we use the same name 'migration_bitmap_rcu' as for migration.
>> +    */
>> +    migration_bitmap_rcu = g_new0(struct BitmapRcu, 1);
>> +    migration_bitmap_rcu->bmap = bitmap_new(ram_cache_pages);
>> +    migration_dirty_pages = 0;
>> +
>>       return 0;
>>
>>   out_locked:
>> @@ -2604,9 +2628,15 @@ out_locked:
>>   void colo_release_ram_cache(void)
>>   {
>>       RAMBlock *block;
>> +    struct BitmapRcu *bitmap = migration_bitmap_rcu;
>>
>>       ram_cache_enable = false;
>>
>> +    atomic_rcu_set(&migration_bitmap_rcu, NULL);
>> +    if (bitmap) {
>> +        call_rcu(bitmap, migration_bitmap_free, rcu);
>> +    }
>> +
>>       rcu_read_lock();
>>       QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
>>           if (block->colo_cache) {
>> --
>> 1.8.3.1
>>
>>
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
>
> .
>