[RFC PATCH 15/17] COLO save: reuse migration bitmap under colo checkpoint

[Yang Hongyang <yanghy@xxxxxxxxxxxxxx>]

reuse migration bitmap under colo checkpoint, only send dirty pages
per-checkpoint.

Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
---
 arch_init.c                        | 20 +++++++++++++++++++-
 include/migration/migration-colo.h |  2 ++
 migration-colo.c                   |  6 ++----
 stubs/migration-colo.c             | 10 ++++++++++
 4 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 8ddaf35..c84e6c8 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -52,6 +52,7 @@
 #include "exec/ram_addr.h"
 #include "hw/acpi/acpi.h"
 #include "qemu/host-utils.h"
+#include "migration/migration-colo.h"
 
 #ifdef DEBUG_ARCH_INIT
 #define DPRINTF(fmt, ...) \
@@ -769,6 +770,15 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
     RAMBlock *block;
     int64_t ram_bitmap_pages; /* Size of bitmap in pages, including gaps */
 
+    /*
+     * migration has already setup the bitmap, reuse it.
+     */
+    if (is_master()) {
+        qemu_mutex_lock_ramlist();
+        reset_ram_globals();
+        goto out_setup;
+    }
+
     mig_throttle_on = false;
     dirty_rate_high_cnt = 0;
     bitmap_sync_count = 0;
@@ -828,6 +838,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
     migration_bitmap_sync();
     qemu_mutex_unlock_iothread();
 
+out_setup:
     qemu_put_be64(f, ram_bytes_total() | RAM_SAVE_FLAG_MEM_SIZE);
 
     QTAILQ_FOREACH(block, &ram_list.blocks, next) {
@@ -937,7 +948,14 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
     }
 
     ram_control_after_iterate(f, RAM_CONTROL_FINISH);
-    migration_end();
+
+    /*
+     * Since we need to reuse dirty bitmap in colo,
+     * don't cleanup the bitmap.
+     */
+    if (!migrate_use_colo() || migration_has_failed(migrate_get_current())) {
+        migration_end();
+    }
 
     qemu_mutex_unlock_ramlist();
     qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
diff --git a/include/migration/migration-colo.h b/include/migration/migration-colo.h
index 861fa27..c286a60 100644
--- a/include/migration/migration-colo.h
+++ b/include/migration/migration-colo.h
@@ -21,10 +21,12 @@ bool colo_supported(void);
 /* save */
 bool migrate_use_colo(void);
 void colo_init_checkpointer(MigrationState *s);
+bool is_master(void);
 
 /* restore */
 bool restore_use_colo(void);
 void restore_exit_colo(void);
+bool is_slave(void);
 
 void colo_process_incoming_checkpoints(QEMUFile *f);
 
diff --git a/migration-colo.c b/migration-colo.c
index 8596845..13a6a57 100644
--- a/migration-colo.c
+++ b/migration-colo.c
@@ -222,8 +222,6 @@ static const QEMUFileOps colo_read_ops = {
 };
 
 /* colo checkpoint control helper */
-static bool is_master(void);
-static bool is_slave(void);
 
 static void ctl_error_handler(void *opaque, int err)
 {
@@ -295,7 +293,7 @@ static int colo_ctl_get(QEMUFile *f, uint64_t require)
 
 /* save */
 
-static bool is_master(void)
+bool is_master(void)
 {
     MigrationState *s = migrate_get_current();
     return (s->state == MIG_STATE_COLO);
@@ -499,7 +497,7 @@ void colo_init_checkpointer(MigrationState *s)
 
 static Coroutine *colo;
 
-static bool is_slave(void)
+bool is_slave(void)
 {
     return colo != NULL;
 }
diff --git a/stubs/migration-colo.c b/stubs/migration-colo.c
index 55f0d37..ef65be6 100644
--- a/stubs/migration-colo.c
+++ b/stubs/migration-colo.c
@@ -22,3 +22,13 @@ void colo_init_checkpointer(MigrationState *s)
 void colo_process_incoming_checkpoints(QEMUFile *f)
 {
 }
+
+bool is_master(void)
+{
+    return false;
+}
+
+bool is_slave(void)
+{
+    return false;
+}
-- 
1.9.1

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