[Qemu-devel] [PATCH] stop the iteration when too many pages is transferred

[Wen Congyang]

When the total sent page size is larger than max_factor
times of the size of guest OS's memory, stop the
iteration.
The default value of max_factor is 3.

This is similar to XEN.


Signed-off-by: Wen Congyang

---
 arch_init.c |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 4486925..67e90f8 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -212,6 +212,14 @@ uint64_t ram_bytes_total(void)
     return total;
 }
 
+static uint64_t ram_blocks_total(void)
+{
+    return ram_bytes_total() / TARGET_PAGE_SIZE;
+}
+
+static uint64_t blocks_transferred = 0;
+static int max_factor = 3;
+
 int ram_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)
 {
     ram_addr_t addr;
@@ -234,6 +242,7 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, 
void *opaque)
         bytes_transferred = 0;
         last_block = NULL;
         last_offset = 0;
+        blocks_transferred = 0;
 
         /* Make sure all dirty bits are set */
         QLIST_FOREACH(block, &ram_list.blocks, next) {
@@ -266,6 +275,7 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, 
void *opaque)
 
         bytes_sent = ram_save_block(f);
         bytes_transferred += bytes_sent;
+        blocks_transferred += !!bytes_sent;
         if (bytes_sent == 0) { /* no more blocks */
             break;
         }
@@ -295,7 +305,8 @@ int ram_save_live(Monitor *mon, QEMUFile *f, int stage, 
void *opaque)
 
     expected_time = ram_save_remaining() * TARGET_PAGE_SIZE / bwidth;
 
-    return (stage == 2) && (expected_time <= migrate_max_downtime());
+    return (stage == 2) && ((expected_time <= migrate_max_downtime())
+            || (blocks_transferred > ram_blocks_total() * max_factor));
 }
 
 static inline void *host_from_stream_offset(QEMUFile *f,
-- 
1.7.1