[Qemu-devel] [PATCH 07/12] savevm: split save_live_setup from save_live_state

[Juan Quintela]

This patch splits stage 1 to its own function for both save_live
users, ram and block.  It is just a copy of the function, removing the
parts of the other stages.  Optimizations would came later.

Signed-off-by: Juan Quintela <address@hidden>
---
 arch_init.c       |   86 +++++++++++++++++++++++++++++++++++++++--------------
 block-migration.c |   35 +++++++++++++++++-----
 savevm.c          |    4 +--
 vmstate.h         |    1 +
 4 files changed, 95 insertions(+), 31 deletions(-)

diff --git a/arch_init.c b/arch_init.c
index 36e19b0..b296e17 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -303,44 +303,85 @@ static void ram_migration_cancel(void *opaque)

 #define MAX_WAIT 50 /* ms, half buffered_file limit */

-static int ram_save_live(QEMUFile *f, int stage, void *opaque)
+static int ram_save_setup(QEMUFile *f, void *opaque)
 {
     ram_addr_t addr;
-    uint64_t bytes_transferred_last;
+    RAMBlock *block;
     double bwidth = 0;
     int ret;
     int i;

     memory_global_sync_dirty_bitmap(get_system_memory());

-    if (stage == 1) {
-        RAMBlock *block;
-        bytes_transferred = 0;
-        last_block = NULL;
-        last_offset = 0;
-        sort_ram_list();
-
-        /* Make sure all dirty bits are set */
-        QLIST_FOREACH(block, &ram_list.blocks, next) {
-            for (addr = 0; addr < block->length; addr += TARGET_PAGE_SIZE) {
-                if (!memory_region_get_dirty(block->mr, addr, TARGET_PAGE_SIZE,
-                                             DIRTY_MEMORY_MIGRATION)) {
-                    memory_region_set_dirty(block->mr, addr, TARGET_PAGE_SIZE);
-                }
+    bytes_transferred = 0;
+    last_block = NULL;
+    last_offset = 0;
+    sort_ram_list();
+
+    /* Make sure all dirty bits are set */
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
+        for (addr = 0; addr < block->length; addr += TARGET_PAGE_SIZE) {
+            if (!memory_region_get_dirty(block->mr, addr, TARGET_PAGE_SIZE,
+                                         DIRTY_MEMORY_MIGRATION)) {
+                memory_region_set_dirty(block->mr, addr, TARGET_PAGE_SIZE);
             }
         }
+    }

-        memory_global_dirty_log_start();
+    memory_global_dirty_log_start();
+
+    qemu_put_be64(f, ram_bytes_total() | RAM_SAVE_FLAG_MEM_SIZE);
+
+    QLIST_FOREACH(block, &ram_list.blocks, next) {
+        qemu_put_byte(f, strlen(block->idstr));
+        qemu_put_buffer(f, (uint8_t *)block->idstr, strlen(block->idstr));
+        qemu_put_be64(f, block->length);
+    }
+
+    bwidth = qemu_get_clock_ns(rt_clock);

-        qemu_put_be64(f, ram_bytes_total() | RAM_SAVE_FLAG_MEM_SIZE);
+    i = 0;
+    while ((ret = qemu_file_rate_limit(f)) == 0) {
+        int bytes_sent;

-        QLIST_FOREACH(block, &ram_list.blocks, next) {
-            qemu_put_byte(f, strlen(block->idstr));
-            qemu_put_buffer(f, (uint8_t *)block->idstr, strlen(block->idstr));
-            qemu_put_be64(f, block->length);
+        bytes_sent = ram_save_block(f);
+        bytes_transferred += bytes_sent;
+        if (bytes_sent == 0) { /* no more blocks */
+            break;
         }
+        /* 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: %ld milliseconds, %d iterations\n", t1, i);
+                break;
+            }
+        }
+        i++;
     }

+    if (ret < 0) {
+        return ret;
+    }
+
+    qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
+
+    return 0;
+}
+
+static int ram_save_live(QEMUFile *f, int stage, void *opaque)
+{
+    uint64_t bytes_transferred_last;
+    double bwidth = 0;
+    int ret;
+    int i;
+
+    memory_global_sync_dirty_bitmap(get_system_memory());
+
     bytes_transferred_last = bytes_transferred;
     bwidth = qemu_get_clock_ns(rt_clock);

@@ -534,6 +575,7 @@ done:
 }

 SaveVMHandlers savevm_ram_handlers = {
+    .save_live_setup = ram_save_setup,
     .save_live_state = ram_save_live,
     .load_state = ram_load,
     .cancel = ram_migration_cancel,
diff --git a/block-migration.c b/block-migration.c
index 6d37dc1..fc3d1f4 100644
--- a/block-migration.c
+++ b/block-migration.c
@@ -541,20 +541,40 @@ static void block_migration_cancel(void *opaque)
     blk_mig_cleanup();
 }

-static int block_save_live(QEMUFile *f, int stage, void *opaque)
+static int block_save_setup(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 setup submitted %d transferred %d\n",
+            block_mig_state.submitted, block_mig_state.transferred);

-    if (stage == 1) {
-        init_blk_migration(f);
+    init_blk_migration(f);
+
+    /* start track dirty blocks */
+    set_dirty_tracking(1);
+
+    flush_blks(f);

-        /* start track dirty blocks */
-        set_dirty_tracking(1);
+    ret = qemu_file_get_error(f);
+    if (ret) {
+        blk_mig_cleanup();
+        return ret;
     }

+    blk_mig_reset_dirty_cursor();
+
+    qemu_put_be64(f, BLK_MIG_FLAG_EOS);
+
+    return 0;
+}
+
+static int block_save_live(QEMUFile *f, int stage, void *opaque)
+{
+    int ret;
+
+    DPRINTF("Enter save live stage %d submitted %d transferred %d\n",
+            stage, block_mig_state.submitted, block_mig_state.transferred);
+
     flush_blks(f);

     ret = qemu_file_get_error(f);
@@ -710,6 +730,7 @@ 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,
     .load_state = block_load,
     .cancel = block_migration_cancel,
diff --git a/savevm.c b/savevm.c
index afa0c9e..0b80a94 100644
--- a/savevm.c
+++ b/savevm.c
@@ -1573,7 +1573,7 @@ int qemu_savevm_state_begin(QEMUFile *f,
     QTAILQ_FOREACH(se, &savevm_handlers, entry) {
         int len;

-        if (!se->ops || !se->ops->save_live_state) {
+        if (!se->ops || !se->ops->save_live_setup) {
             continue;
         }
         if (se->ops && se->ops->is_active) {
@@ -1593,7 +1593,7 @@ int qemu_savevm_state_begin(QEMUFile *f,
         qemu_put_be32(f, se->instance_id);
         qemu_put_be32(f, se->version_id);

-        ret = se->ops->save_live_state(f, QEMU_VM_SECTION_START, se->opaque);
+        ret = se->ops->save_live_setup(f, se->opaque);
         if (ret < 0) {
             qemu_savevm_state_cancel(f);
             return ret;
diff --git a/vmstate.h b/vmstate.h
index 96651a5..049f2b7 100644
--- a/vmstate.h
+++ b/vmstate.h
@@ -32,6 +32,7 @@ typedef int LoadStateHandler(QEMUFile *f, void *opaque, int 
version_id);
 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);
     void (*cancel)(void *opaque);
     LoadStateHandler *load_state;
-- 
1.7.10.2