On 07/18/2016 10:57 AM, Max Reitz wrote:
> On 15.07.2016 22:27, John Snow wrote:
>> From: Fam Zheng <[email protected]>
>>
>> The added group of operations enables tracking of the changed bits in
>> the dirty bitmap.
>>
>> Signed-off-by: Fam Zheng <[email protected]>
>> Reviewed-by: Max Reitz <[email protected]>
>> Signed-off-by: John Snow <[email protected]>
>> ---
>> block/dirty-bitmap.c | 52
>> ++++++++++++++++++++++++++++++++++++++++++++
>> include/block/dirty-bitmap.h | 9 ++++++++
>> 2 files changed, 61 insertions(+)
>>
>> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
>> index 628b77c..9c53c56 100644
>> --- a/block/dirty-bitmap.c
>> +++ b/block/dirty-bitmap.c
>> @@ -38,6 +38,7 @@
>
> [...]
>
>> +int bdrv_dirty_bitmap_get_meta(BlockDriverState *bs,
>> + BdrvDirtyBitmap *bitmap, int64_t sector,
>> + int nb_sectors)
>> +{
>> + uint64_t i;
>> + int gran = bdrv_dirty_bitmap_granularity(bitmap) >> BDRV_SECTOR_BITS;
>> +
>> + /* To optimize: we can make hbitmap to internally check the range in a
>> + * coarse level, or at least do it word by word. */
>
> So you really want to leave even the simple optimizations for later? :-)
>
I guess partly I felt bad about not going all the way on it, but I can
bring it a little closer :)
> (i.e. "int gran = hbitmap_granularity(bitmap->meta);")
>
> Max
>
>> + for (i = sector; i < sector + nb_sectors; i += gran) {
>> + if (hbitmap_get(bitmap->meta, i)) {
>> + return true;
>> + }
>> + }
>> + return false;
>> +}
>
>
