[Qemu-devel] [PATCH 08/22] savevm: split save_live into stage2 and stage3

[Juan Quintela <quintela@redhat.com>]

We split it into 2 functions, foo_live_iterate, and foo_live_complete.
At this point, we only remove the bits that are for the other stage,
functionally this is equivalent to previous code.

Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 arch_init.c       |   72 +++++++++++++++++++++++++++++---------
 block-migration.c |   99 ++++++++++++++++++++++++++++++++---------------------
 savevm.c          |   10 +++---
 vmstate.h         |    3 +-
 4 files changed, 122 insertions(+), 62 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 2a4903c..7e04ea5 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -374,12 +374,13 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
     return 0;
 }

-static int ram_save_live(QEMUFile *f, int stage, void *opaque)
+static int ram_save_iterate(QEMUFile *f, void *opaque)
 {
     uint64_t bytes_transferred_last;
     double bwidth = 0;
     int ret;
     int i;
+    uint64_t expected_time;

     memory_global_sync_dirty_bitmap(get_system_memory());

@@ -424,28 +425,64 @@ static int ram_save_live(QEMUFile *f, int stage, void *opaque)
         bwidth = 0.000001;
     }

-    /* try transferring iterative blocks of memory */
-    if (stage == 3) {
-        int bytes_sent;
+    qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
+
+    expected_time = ram_save_remaining() * TARGET_PAGE_SIZE / bwidth;
+
+    DPRINTF("ram_save_live: expected(" PRIu64 ") <= max(" PRIu64 ")?\n",
+            expected_time, migrate_max_downtime());
+
+    return expected_time <= migrate_max_downtime();
+}
+
+static int ram_save_complete(QEMUFile *f, void *opaque)
+{
+    double bwidth = 0;
+    int ret;
+    int i;
+    int bytes_sent;

-        /* flush all remaining blocks regardless of rate limiting */
-        while ((bytes_sent = ram_save_block(f)) != 0) {
-            bytes_transferred += bytes_sent;
+    memory_global_sync_dirty_bitmap(get_system_memory());
+
+    bwidth = qemu_get_clock_ns(rt_clock);
+
+    i = 0;
+    while ((ret = qemu_file_rate_limit(f)) == 0) {
+        bytes_sent = ram_save_block(f);
+        bytes_transferred += bytes_sent;
+        if (bytes_sent == 0) { /* no more blocks */
+            break;
         }
-        memory_global_dirty_log_stop();
+        /* we want to check in the 1st loop, just in case it was the 1st time
+           and we had to sync the dirty bitmap.
+           qemu_get_clock_ns() is a bit expensive, so we only check each some
+           iterations
+        */
+        if ((i & 63) == 0) {
+            uint64_t t1 = (qemu_get_clock_ns(rt_clock) - bwidth) / 1000000;
+            if (t1 > MAX_WAIT) {
+                DPRINTF("big wait: " PRIu64 " milliseconds, %d iterations\n",
+                        t1, i);
+                break;
+            }
+        }
+        i++;
     }

-    qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
-
-    if (stage == 2) {
-        uint64_t expected_time;
-        expected_time = ram_save_remaining() * TARGET_PAGE_SIZE / bwidth;
+    if (ret < 0) {
+        return ret;
+    }

-        DPRINTF("ram_save_live: expected(" PRIu64 ") <= max(" PRIu64 ")?\n",
-                expected_time, migrate_max_downtime());
+    /* try transferring iterative blocks of memory */

-        return expected_time <= migrate_max_downtime();
+    /* flush all remaining blocks regardless of rate limiting */
+    while ((bytes_sent = ram_save_block(f)) != 0) {
+        bytes_transferred += bytes_sent;
     }
+    memory_global_dirty_log_stop();
+
+    qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
+
     return 0;
 }

@@ -578,7 +615,8 @@ done:

 SaveVMHandlers savevm_ram_handlers = {
     .save_live_setup = ram_save_setup,
-    .save_live_state = ram_save_live,
+    .save_live_iterate = ram_save_iterate,
+    .save_live_complete = ram_save_complete,
     .load_state = ram_load,
     .cancel = ram_migration_cancel,
 };
diff --git a/block-migration.c b/block-migration.c
index fc3d1f4..7def8ab 100644
--- a/block-migration.c
+++ b/block-migration.c
@@ -568,12 +568,12 @@ static int block_save_setup(QEMUFile *f, void *opaque)
     return 0;
 }

-static int block_save_live(QEMUFile *f, int stage, void *opaque)
+static int block_save_iterate(QEMUFile *f, void *opaque)
 {
     int ret;

-    DPRINTF("Enter save live stage %d submitted %d transferred %d\n",
-            stage, block_mig_state.submitted, block_mig_state.transferred);
+    DPRINTF("Enter save live iterate submitted %d transferred %d\n",
+            block_mig_state.submitted, block_mig_state.transferred);

     flush_blks(f);

@@ -585,56 +585,76 @@ static int block_save_live(QEMUFile *f, int stage, void *opaque)

     blk_mig_reset_dirty_cursor();

-    if (stage == 2) {
-        /* control the rate of transfer */
-        while ((block_mig_state.submitted +
-                block_mig_state.read_done) * BLOCK_SIZE <
-               qemu_file_get_rate_limit(f)) {
-            if (block_mig_state.bulk_completed == 0) {
-                /* first finish the bulk phase */
-                if (blk_mig_save_bulked_block(f) == 0) {
-                    /* finished saving bulk on all devices */
-                    block_mig_state.bulk_completed = 1;
-                }
-            } else {
-                if (blk_mig_save_dirty_block(f, 1) == 0) {
-                    /* no more dirty blocks */
-                    break;
-                }
+    /* control the rate of transfer */
+    while ((block_mig_state.submitted +
+            block_mig_state.read_done) * BLOCK_SIZE <
+           qemu_file_get_rate_limit(f)) {
+        if (block_mig_state.bulk_completed == 0) {
+            /* first finish the bulk phase */
+            if (blk_mig_save_bulked_block(f) == 0) {
+                /* finished saving bulk on all devices */
+                block_mig_state.bulk_completed = 1;
+            }
+        } else {
+            if (blk_mig_save_dirty_block(f, 1) == 0) {
+                /* no more dirty blocks */
+                break;
             }
         }
+    }

-        flush_blks(f);
+    flush_blks(f);

-        ret = qemu_file_get_error(f);
-        if (ret) {
-            blk_mig_cleanup();
-            return ret;
-        }
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        blk_mig_cleanup();
+        return ret;
     }

-    if (stage == 3) {
-        /* we know for sure that save bulk is completed and
-           all async read completed */
-        assert(block_mig_state.submitted == 0);
+    qemu_put_be64(f, BLK_MIG_FLAG_EOS);
+
+    return is_stage2_completed();
+}
+
+static int block_save_complete(QEMUFile *f, void *opaque)
+{
+    int ret;
+
+    DPRINTF("Enter save live complete submitted %d transferred %d\n",
+            block_mig_state.submitted, block_mig_state.transferred);
+
+    flush_blks(f);

-        while (blk_mig_save_dirty_block(f, 0) != 0);
+    ret = qemu_file_get_error(f);
+    if (ret) {
         blk_mig_cleanup();
+        return ret;
+    }

-        /* report completion */
-        qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
+    blk_mig_reset_dirty_cursor();

-        ret = qemu_file_get_error(f);
-        if (ret) {
-            return ret;
-        }
+    /* we know for sure that save bulk is completed and
+       all async read completed */
+    assert(block_mig_state.submitted == 0);
+
+    while (blk_mig_save_dirty_block(f, 0) != 0) {
+        /* Do nothing */
+    }
+    blk_mig_cleanup();
+
+    /* report completion */
+    qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);

-        DPRINTF("Block migration completed\n");
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        return ret;
     }

+    DPRINTF("Block migration completed\n");
+
     qemu_put_be64(f, BLK_MIG_FLAG_EOS);

-    return ((stage == 2) && is_stage2_completed());
+    return 0;
 }

 static int block_load(QEMUFile *f, void *opaque, int version_id)
@@ -731,7 +751,8 @@ static bool block_is_active(void *opaque)
 SaveVMHandlers savevm_block_handlers = {
     .set_params = block_set_params,
     .save_live_setup = block_save_setup,
-    .save_live_state = block_save_live,
+    .save_live_iterate = block_save_iterate,
+    .save_live_complete = block_save_complete,
     .load_state = block_load,
     .cancel = block_migration_cancel,
     .is_active = block_is_active,
diff --git a/savevm.c b/savevm.c
index 0b80a94..6e82b2d 100644
--- a/savevm.c
+++ b/savevm.c
@@ -1236,7 +1236,7 @@ int register_savevm_live(DeviceState *dev,
     se->vmsd = NULL;
     se->no_migrate = 0;
     /* if this is a live_savem then set is_ram */
-    if (ops->save_live_state != NULL) {
+    if (ops->save_live_setup != NULL) {
         se->is_ram = 1;
     }

@@ -1620,7 +1620,7 @@ int qemu_savevm_state_iterate(QEMUFile *f)
     int ret = 1;

     QTAILQ_FOREACH(se, &savevm_handlers, entry) {
-        if (!se->ops || !se->ops->save_live_state) {
+        if (!se->ops || !se->ops->save_live_iterate) {
             continue;
         }
         if (se->ops && se->ops->is_active) {
@@ -1636,7 +1636,7 @@ int qemu_savevm_state_iterate(QEMUFile *f)
         qemu_put_byte(f, QEMU_VM_SECTION_PART);
         qemu_put_be32(f, se->section_id);

-        ret = se->ops->save_live_state(f, QEMU_VM_SECTION_PART, se->opaque);
+        ret = se->ops->save_live_iterate(f, se->opaque);
         trace_savevm_section_end(se->section_id);

         if (ret <= 0) {
@@ -1665,7 +1665,7 @@ int qemu_savevm_state_complete(QEMUFile *f)
     cpu_synchronize_all_states();

     QTAILQ_FOREACH(se, &savevm_handlers, entry) {
-        if (!se->ops || !se->ops->save_live_state) {
+        if (!se->ops || !se->ops->save_live_complete) {
             continue;
         }
         if (se->ops && se->ops->is_active) {
@@ -1678,7 +1678,7 @@ int qemu_savevm_state_complete(QEMUFile *f)
         qemu_put_byte(f, QEMU_VM_SECTION_END);
         qemu_put_be32(f, se->section_id);

-        ret = se->ops->save_live_state(f, QEMU_VM_SECTION_END, se->opaque);
+        ret = se->ops->save_live_complete(f, se->opaque);
         trace_savevm_section_end(se->section_id);
         if (ret < 0) {
             return ret;
diff --git a/vmstate.h b/vmstate.h
index 049f2b7..5bd2b76 100644
--- a/vmstate.h
+++ b/vmstate.h
@@ -33,7 +33,8 @@ typedef struct SaveVMHandlers {
     void (*set_params)(const MigrationParams *params, void * opaque);
     SaveStateHandler *save_state;
     int (*save_live_setup)(QEMUFile *f, void *opaque);
-    int (*save_live_state)(QEMUFile *f, int stage, void *opaque);
+    int (*save_live_iterate)(QEMUFile *f, void *opaque);
+    int (*save_live_complete)(QEMUFile *f, void *opaque);
     void (*cancel)(void *opaque);
     LoadStateHandler *load_state;
     bool (*is_active)(void *opaque);
-- 
1.7.10.4