On 10/18/2012 09:30 AM, Juan Quintela wrote:
> Instead of testing each page individually, we search what is the next
> dirty page with a bitmap operation. We have to reorganize the code to
> move from a "for" loop, to a while(dirty) loop.
>
> Signed-off-by: Juan Quintela <quint...@redhat.com>
> ---
> arch_init.c | 45 ++++++++++++++++++++++++++-------------------
> 1 file changed, 26 insertions(+), 19 deletions(-)
>
> diff --git a/arch_init.c b/arch_init.c
> index 8391375..cd6ebef 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -343,18 +343,21 @@ static unsigned long *migration_bitmap;
> static uint64_t migration_dirty_pages;
> static uint32_t last_version;
>
> -static inline bool migration_bitmap_test_and_reset_dirty(MemoryRegion *mr,
> - ram_addr_t offset)
> +static inline
> +ram_addr_t migration_bitmap_find_and_reset_dirty(MemoryRegion *mr,
> + ram_addr_t start)
> {
> - bool ret;
> - int nr = (mr->ram_addr + offset) >> TARGET_PAGE_BITS;
> + unsigned long base = mr->ram_addr >> TARGET_PAGE_BITS;
> + unsigned long nr = base + (start >> TARGET_PAGE_BITS);
> + unsigned long size = base + (int128_get64(mr->size) >> TARGET_PAGE_BITS);
>
> - ret = test_and_clear_bit(nr, migration_bitmap);
> + unsigned long next = find_next_bit(migration_bitmap, size, nr);
>
> - if (ret) {
> + if (next < size) {
> + clear_bit(next, migration_bitmap);
> migration_dirty_pages--;
> }
> - return ret;
> + return (next - base) << TARGET_PAGE_BITS;
> }
>
> static inline bool migration_bitmap_set_dirty(MemoryRegion *mr,
> @@ -423,6 +426,7 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
> {
> RAMBlock *block = last_seen_block;
> ram_addr_t offset = last_offset;
> + bool complete_round = false;
> int bytes_sent = -1;
> MemoryRegion *mr;
> ram_addr_t current_addr;
> @@ -430,9 +434,21 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
> if (!block)
> block = QLIST_FIRST(&ram_list.blocks);
>
> - do {
> + while(true) {
> mr = block->mr;
> - if (migration_bitmap_test_and_reset_dirty(mr, offset)) {
> + offset = migration_bitmap_find_and_reset_dirty(mr, offset);
> + if (complete_round && block == last_seen_block &&
> + offset >= last_offset) {
> + break;
> + }
Juan,
You need to exchange those line, first check to see you did a full round than
calculate and reset the offset, in the way it is written now you may reset a
bit and than break of the loop
without sending it.
Orit
> + if (offset >= block->length) {
> + offset = 0;
> + block = QLIST_NEXT(block, next);
> + if (!block) {
> + block = QLIST_FIRST(&ram_list.blocks);
> + complete_round = true;
> + }
> + } else {
> uint8_t *p;
> int cont = (block == last_sent_block) ?
> RAM_SAVE_FLAG_CONTINUE : 0;
> @@ -467,16 +483,7 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
> break;
> }
> }
> -
> - offset += TARGET_PAGE_SIZE;
> - if (offset >= block->length) {
> - offset = 0;
> - block = QLIST_NEXT(block, next);
> - if (!block)
> - block = QLIST_FIRST(&ram_list.blocks);
> - }
> - } while (block != last_seen_block || offset != last_offset);
> -
> + }
> last_seen_block = block;
> last_offset = offset;
>
