On 1/18/24 14:37, Denis V. Lunev wrote:
On 12/28/23 11:12, Alexander Ivanov wrote:
If all the bits in a dirty bitmap cluster are ones, the cluster
shouldn't
be written. Instead the corresponding L1 entry should be set to 1.
Check if all bits in a memory region are ones and set 1 to L1 entries
corresponding clusters filled with ones.
Signed-off-by: Alexander Ivanov <alexander.iva...@virtuozzo.com>
---
block/parallels-ext.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/block/parallels-ext.c b/block/parallels-ext.c
index 195b01b109..033ca3ec3a 100644
--- a/block/parallels-ext.c
+++ b/block/parallels-ext.c
@@ -354,7 +354,7 @@ static void GRAPH_RDLOCK
parallels_save_bitmap(BlockDriverState *bs,
offset = 0;
while ((offset = bdrv_dirty_bitmap_next_dirty(bitmap, offset,
bm_size)) >= 0) {
uint64_t idx = offset / limit;
- int64_t cluster_off, end, write_size;
+ int64_t cluster_off, end, write_size, first_zero;
offset = QEMU_ALIGN_DOWN(offset, limit);
end = MIN(bm_size, offset + limit);
@@ -367,6 +367,16 @@ static void GRAPH_RDLOCK
parallels_save_bitmap(BlockDriverState *bs,
memset(bm_buf + write_size, 0, s->cluster_size -
write_size);
}
+ first_zero = bdrv_dirty_bitmap_next_zero(bitmap, offset,
bm_size);
+ if (first_zero < 0) {
+ goto end;
+ }
+ if (first_zero - offset >= s->cluster_size) {
+ l1_table[idx] = 1;
+ offset = end;
+ continue;
+ }
+
cluster_off = parallels_allocate_host_clusters(bs,
&alloc_size);
if (cluster_off <= 0) {
goto end;
That is not enough. We should handle all-one and all-zeroes according
to the spec and all-zeroes would be much more common.
Buffer for extensions contains zeroes before handling (it was allocated with
qemu_blockalign0). We skip all all-zeroes l1 entries and the stay zeroed.
--
Best regards,
Alexander Ivanov
