migration: Split save_live_pending() into state_pending_*

We split the function into to:

- state_pending_estimate: We estimate the remaining state size without
  stopping the machine.

- state pending_exact: We calculate the exact amount of remaining
  state.

The only "device" that implements different functions for _estimate()
and _exact() is ram.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

7 files changed, 101 insertions, 43 deletions

diff --git a/migration/block-dirty-bitmap.c b/migration/block-dirty-bitmap.c
index c27ef9b033..6fac9fb34f 100644
--- a/migration/block-dirty-bitmap.c
+++ b/migration/block-dirty-bitmap.c
@@ -762,11 +762,11 @@ static int dirty_bitmap_save_complete(QEMUFile *f, void *opaque)
     return 0;
 }
 
-static void dirty_bitmap_save_pending(void *opaque,
-                                      uint64_t max_size,
-                                      uint64_t *res_precopy_only,
-                                      uint64_t *res_compatible,
-                                      uint64_t *res_postcopy_only)
+static void dirty_bitmap_state_pending(void *opaque,
+                                       uint64_t max_size,
+                                       uint64_t *res_precopy_only,
+                                       uint64_t *res_compatible,
+                                       uint64_t *res_postcopy_only)
 {
     DBMSaveState *s = &((DBMState *)opaque)->save;
     SaveBitmapState *dbms;
@@ -784,7 +784,7 @@ static void dirty_bitmap_save_pending(void *opaque,
 
     qemu_mutex_unlock_iothread();
 
-    trace_dirty_bitmap_save_pending(pending, max_size);
+    trace_dirty_bitmap_state_pending(pending);
 
     *res_postcopy_only += pending;
 }
@@ -1253,7 +1253,8 @@ static SaveVMHandlers savevm_dirty_bitmap_handlers = {
     .save_live_complete_postcopy = dirty_bitmap_save_complete,
     .save_live_complete_precopy = dirty_bitmap_save_complete,
     .has_postcopy = dirty_bitmap_has_postcopy,
-    .save_live_pending = dirty_bitmap_save_pending,
+    .state_pending_exact = dirty_bitmap_state_pending,
+    .state_pending_estimate = dirty_bitmap_state_pending,
     .save_live_iterate = dirty_bitmap_save_iterate,
     .is_active_iterate = dirty_bitmap_is_active_iterate,
     .load_state = dirty_bitmap_load,
diff --git a/migration/block.c b/migration/block.c
index 47852b8d58..544e74e9c5 100644
--- a/migration/block.c
+++ b/migration/block.c
@@ -863,10 +863,10 @@ static int block_save_complete(QEMUFile *f, void *opaque)
     return 0;
 }
 
-static void block_save_pending(void *opaque, uint64_t max_size,
-                               uint64_t *res_precopy_only,
-                               uint64_t *res_compatible,
-                               uint64_t *res_postcopy_only)
+static void block_state_pending(void *opaque, uint64_t max_size,
+                                uint64_t *res_precopy_only,
+                                uint64_t *res_compatible,
+                                uint64_t *res_postcopy_only)
 {
     /* Estimate pending number of bytes to send */
     uint64_t pending;
@@ -885,7 +885,7 @@ static void block_save_pending(void *opaque, uint64_t max_size,
         pending = BLK_MIG_BLOCK_SIZE;
     }
 
-    trace_migration_block_save_pending(pending);
+    trace_migration_block_state_pending(pending);
     /* We don't do postcopy */
     *res_precopy_only += pending;
 }
@@ -1020,7 +1020,8 @@ static SaveVMHandlers savevm_block_handlers = {
     .save_setup = block_save_setup,
     .save_live_iterate = block_save_iterate,
     .save_live_complete_precopy = block_save_complete,
-    .save_live_pending = block_save_pending,
+    .state_pending_exact = block_state_pending,
+    .state_pending_estimate = block_state_pending,
     .load_state = block_load,
     .save_cleanup = block_migration_cleanup,
     .is_active = block_is_active,
diff --git a/migration/migration.c b/migration/migration.c
index 5e2c891845..877a6f7011 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3778,15 +3778,23 @@ typedef enum {
  */
 static MigIterateState migration_iteration_run(MigrationState *s)
 {
-    uint64_t pending_size, pend_pre, pend_compat, pend_post;
+    uint64_t pend_pre, pend_compat, pend_post;
     bool in_postcopy = s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE;
 
-    qemu_savevm_state_pending(s->threshold_size, &pend_pre,
-                              &pend_compat, &pend_post);
-    pending_size = pend_pre + pend_compat + pend_post;
+    qemu_savevm_state_pending_estimate(s->threshold_size, &pend_pre,
+                                       &pend_compat, &pend_post);
+    uint64_t pending_size = pend_pre + pend_compat + pend_post;
 
-    trace_migrate_pending(pending_size, s->threshold_size,
-                          pend_pre, pend_compat, pend_post);
+    trace_migrate_pending_estimate(pending_size, s->threshold_size,
+                                   pend_pre, pend_compat, pend_post);
+
+    if (pend_pre + pend_compat <= s->threshold_size) {
+        qemu_savevm_state_pending_exact(s->threshold_size, &pend_pre,
+                                        &pend_compat, &pend_post);
+        pending_size = pend_pre + pend_compat + pend_post;
+        trace_migrate_pending_exact(pending_size, s->threshold_size,
+                                    pend_pre, pend_compat, pend_post);
+    }
 
     if (pending_size && pending_size >= s->threshold_size) {
         /* Still a significant amount to transfer */
diff --git a/migration/ram.c b/migration/ram.c
index 389739f162..56ff9cd29d 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3409,19 +3409,35 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
     return 0;
 }
 
-static void ram_save_pending(void *opaque, uint64_t max_size,
-                             uint64_t *res_precopy_only,
-                             uint64_t *res_compatible,
-                             uint64_t *res_postcopy_only)
+static void ram_state_pending_estimate(void *opaque, uint64_t max_size,
+                                       uint64_t *res_precopy_only,
+                                       uint64_t *res_compatible,
+                                       uint64_t *res_postcopy_only)
 {
     RAMState **temp = opaque;
     RAMState *rs = *temp;
-    uint64_t remaining_size;
 
-    remaining_size = rs->migration_dirty_pages * TARGET_PAGE_SIZE;
+    uint64_t remaining_size = rs->migration_dirty_pages * TARGET_PAGE_SIZE;
 
-    if (!migration_in_postcopy() &&
-        remaining_size < max_size) {
+    if (migrate_postcopy_ram()) {
+        /* We can do postcopy, and all the data is postcopiable */
+        *res_postcopy_only += remaining_size;
+    } else {
+        *res_precopy_only += remaining_size;
+    }
+}
+
+static void ram_state_pending_exact(void *opaque, uint64_t max_size,
+                                    uint64_t *res_precopy_only,
+                                    uint64_t *res_compatible,
+                                    uint64_t *res_postcopy_only)
+{
+    RAMState **temp = opaque;
+    RAMState *rs = *temp;
+
+    uint64_t remaining_size = rs->migration_dirty_pages * TARGET_PAGE_SIZE;
+
+    if (!migration_in_postcopy()) {
         qemu_mutex_lock_iothread();
         WITH_RCU_READ_LOCK_GUARD() {
             migration_bitmap_sync_precopy(rs);
@@ -4577,7 +4593,8 @@ static SaveVMHandlers savevm_ram_handlers = {
     .save_live_complete_postcopy = ram_save_complete,
     .save_live_complete_precopy = ram_save_complete,
     .has_postcopy = ram_has_postcopy,
-    .save_live_pending = ram_save_pending,
+    .state_pending_exact = ram_state_pending_exact,
+    .state_pending_estimate = ram_state_pending_estimate,
     .load_state = ram_load,
     .save_cleanup = ram_save_cleanup,
     .load_setup = ram_load_setup,
diff --git a/migration/savevm.c b/migration/savevm.c
index 5e4bccb966..7f9f770c1e 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1472,10 +1472,10 @@ flush:
  * the result is split into the amount for units that can and
  * for units that can't do postcopy.
  */
-void qemu_savevm_state_pending(uint64_t threshold_size,
-                               uint64_t *res_precopy_only,
-                               uint64_t *res_compatible,
-                               uint64_t *res_postcopy_only)
+void qemu_savevm_state_pending_estimate(uint64_t threshold_size,
+                                        uint64_t *res_precopy_only,
+                                        uint64_t *res_compatible,
+                                        uint64_t *res_postcopy_only)
 {
     SaveStateEntry *se;
 
@@ -1485,7 +1485,7 @@ void qemu_savevm_state_pending(uint64_t threshold_size,
 
 
     QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
-        if (!se->ops || !se->ops->save_live_pending) {
+        if (!se->ops || !se->ops->state_pending_exact) {
             continue;
         }
         if (se->ops->is_active) {
@@ -1493,9 +1493,35 @@ void qemu_savevm_state_pending(uint64_t threshold_size,
                 continue;
             }
         }
-        se->ops->save_live_pending(se->opaque, threshold_size,
-                                   res_precopy_only, res_compatible,
-                                   res_postcopy_only);
+        se->ops->state_pending_exact(se->opaque, threshold_size,
+                                     res_precopy_only, res_compatible,
+                                     res_postcopy_only);
+    }
+}
+
+void qemu_savevm_state_pending_exact(uint64_t threshold_size,
+                                     uint64_t *res_precopy_only,
+                                     uint64_t *res_compatible,
+                                     uint64_t *res_postcopy_only)
+{
+    SaveStateEntry *se;
+
+    *res_precopy_only = 0;
+    *res_compatible = 0;
+    *res_postcopy_only = 0;
+
+    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
+        if (!se->ops || !se->ops->state_pending_estimate) {
+            continue;
+        }
+        if (se->ops->is_active) {
+            if (!se->ops->is_active(se->opaque)) {
+                continue;
+            }
+        }
+        se->ops->state_pending_estimate(se->opaque, threshold_size,
+                                        res_precopy_only, res_compatible,
+                                        res_postcopy_only);
     }
 }
 
diff --git a/migration/savevm.h b/migration/savevm.h
index 524cf12f25..5d2cff4411 100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -40,10 +40,14 @@ void qemu_savevm_state_cleanup(void);
 void qemu_savevm_state_complete_postcopy(QEMUFile *f);
 int qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only,
                                        bool inactivate_disks);
-void qemu_savevm_state_pending(uint64_t max_size,
-                               uint64_t *res_precopy_only,
-                               uint64_t *res_compatible,
-                               uint64_t *res_postcopy_only);
+void qemu_savevm_state_pending_exact(uint64_t threshold_size,
+                                     uint64_t *res_precopy_only,
+                                     uint64_t *res_compatible,
+                                     uint64_t *res_postcopy_only);
+void qemu_savevm_state_pending_estimate(uint64_t thershold_size,
+                                        uint64_t *res_precopy_only,
+                                        uint64_t *res_compatible,
+                                        uint64_t *res_postcopy_only);
 void qemu_savevm_send_ping(QEMUFile *f, uint32_t value);
 void qemu_savevm_send_open_return_path(QEMUFile *f);
 int qemu_savevm_send_packaged(QEMUFile *f, const uint8_t *buf, size_t len);
diff --git a/migration/trace-events b/migration/trace-events
index 57003edcbd..adb680b0e6 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -150,7 +150,8 @@ migrate_fd_cleanup(void) ""
 migrate_fd_error(const char *error_desc) "error=%s"
 migrate_fd_cancel(void) ""
 migrate_handle_rp_req_pages(const char *rbname, size_t start, size_t len) "in %s at 0x%zx len 0x%zx"
-migrate_pending(uint64_t size, uint64_t max, uint64_t pre, uint64_t compat, uint64_t post) "pending size %" PRIu64 " max %" PRIu64 " (pre = %" PRIu64 " compat=%" PRIu64 " post=%" PRIu64 ")"
+migrate_pending_exact(uint64_t size, uint64_t max, uint64_t pre, uint64_t compat, uint64_t post) "exact pending size %" PRIu64 " max %" PRIu64 " (pre = %" PRIu64 " compat=%" PRIu64 " post=%" PRIu64 ")"
+migrate_pending_estimate(uint64_t size, uint64_t max, uint64_t pre, uint64_t compat, uint64_t post) "estimate pending size %" PRIu64 " max %" PRIu64 " (pre = %" PRIu64 " compat=%" PRIu64 " post=%" PRIu64 ")"
 migrate_send_rp_message(int msg_type, uint16_t len) "%d: len %d"
 migrate_send_rp_recv_bitmap(char *name, int64_t size) "block '%s' size 0x%"PRIi64
 migration_completion_file_err(void) ""
@@ -330,7 +331,7 @@ send_bitmap_bits(uint32_t flags, uint64_t start_sector, uint32_t nr_sectors, uin
 dirty_bitmap_save_iterate(int in_postcopy) "in postcopy: %d"
 dirty_bitmap_save_complete_enter(void) ""
 dirty_bitmap_save_complete_finish(void) ""
-dirty_bitmap_save_pending(uint64_t pending, uint64_t max_size) "pending %" PRIu64 " max: %" PRIu64
+dirty_bitmap_state_pending(uint64_t pending) "pending %" PRIu64
 dirty_bitmap_load_complete(void) ""
 dirty_bitmap_load_bits_enter(uint64_t first_sector, uint32_t nr_sectors) "chunk: %" PRIu64 " %" PRIu32
 dirty_bitmap_load_bits_zeroes(void) ""
@@ -355,7 +356,7 @@ migration_block_save_device_dirty(int64_t sector) "Error reading sector %" PRId6
 migration_block_flush_blks(const char *action, int submitted, int read_done, int transferred) "%s submitted %d read_done %d transferred %d"
 migration_block_save(const char *mig_stage, int submitted, int transferred) "Enter save live %s submitted %d transferred %d"
 migration_block_save_complete(void) "Block migration completed"
-migration_block_save_pending(uint64_t pending) "Enter save live pending  %" PRIu64
+migration_block_state_pending(uint64_t pending) "Enter save live pending  %" PRIu64
 
 # page_cache.c
 migration_pagecache_init(int64_t max_num_items) "Setting cache buckets to %" PRId64