[PATCH v1 1/1] COLO: only flush dirty ram pages from colo cache

[Derek Su]

In secondary side, the colo_flush_ram_cache() calls
migration_bitmap_find_dirty() to finding the dirty pages and
flush them to host. But ram_state's ram_bulk_stage flag is always
enabled in secondary side, it leads to the whole ram pages copy
instead of only dirty pages.

Here, the ram_bulk_stage in secondary side is disabled in the
preparation of COLO incoming process to avoid the whole dirty
ram pages flush.

Signed-off-by: Derek Su <dere...@qnap.com>
---
 migration/colo.c |  6 +++++-
 migration/ram.c  | 10 ++++++++++
 migration/ram.h  |  3 +++
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/migration/colo.c b/migration/colo.c
index ea7d1e9d4e..6e644db306 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -844,6 +844,8 @@ void *colo_process_incoming_thread(void *opaque)
         return NULL;
     }
 
+    colo_disable_ram_bulk_stage();
+
     failover_init_state();
 
     mis->to_src_file = qemu_file_get_return_path(mis->from_src_file);
@@ -873,7 +875,7 @@ void *colo_process_incoming_thread(void *opaque)
         goto out;
     }
 #else
-        abort();
+    abort();
 #endif
     vm_start();
     trace_colo_vm_state_change("stop", "run");
@@ -924,6 +926,8 @@ out:
         qemu_fclose(fb);
     }
 
+    colo_enable_ram_bulk_stage();
+
     /* Hope this not to be too long to loop here */
     qemu_sem_wait(&mis->colo_incoming_sem);
     qemu_sem_destroy(&mis->colo_incoming_sem);
diff --git a/migration/ram.c b/migration/ram.c
index 76d4fee5d5..65e9b12058 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3357,6 +3357,16 @@ static bool postcopy_is_running(void)
     return ps >= POSTCOPY_INCOMING_LISTENING && ps < POSTCOPY_INCOMING_END;
 }
 
+void colo_enable_ram_bulk_stage(void)
+{
+    ram_state->ram_bulk_stage = true;
+}
+
+void colo_disable_ram_bulk_stage(void)
+{
+    ram_state->ram_bulk_stage = false;
+}
+
 /*
  * Flush content of RAM cache into SVM's memory.
  * Only flush the pages that be dirtied by PVM or SVM or both.
diff --git a/migration/ram.h b/migration/ram.h
index 2eeaacfa13..c1c0ebbe0f 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -69,4 +69,7 @@ void colo_flush_ram_cache(void);
 void colo_release_ram_cache(void);
 void colo_incoming_start_dirty_log(void);
 
+void colo_enable_ram_bulk_stage(void);
+void colo_disable_ram_bulk_stage(void);
+
 #endif
-- 
2.25.1