[Qemu-devel] [RFC][PATCH 8/9] migration: do not sent zero_pages in bulk stage

[Peter Lieven <pl@dlhnet.de>]

if the dup_page is a zero_page do not send it at all.
the memory at the destination reads as zero anyway.

Signed-off-by: Peter Lieven <pl@kamp.de>
---
  arch_init.c |    6 ++++--
  1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 04c82e4..abd54a7 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -447,9 +447,11 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
              bytes_sent = -1;
              if (ram_bulk_stage && is_dup_page(p)) {
                  acct_info.dup_pages++;
-                bytes_sent = save_block_hdr(f, block, offset, cont,
+                if (p[0]) {
+                    bytes_sent = save_block_hdr(f, block, offset, cont,
                                              RAM_SAVE_FLAG_COMPRESS);
-                qemu_put_byte(f, *p);
+                    qemu_put_byte(f, *p);
+                }
                  bytes_sent += 1;
              } else if (!ram_bulk_stage && migrate_use_xbzrle()) {
                  current_addr = block->offset + offset;
-- 
1.7.9.5