savevm: Create a new continue flag to avoid resending block name
Allows us to compress the protocol a bit by setting a flag on the
offset which indicates we're still working within the same block
as last time. That way we can avoid sending the block name for
every page. Suggested by Anthony Liguori.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/arch_init.c b/arch_init.c
index 186645b..2f082f3 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -87,6 +87,7 @@
#define RAM_SAVE_FLAG_MEM_SIZE 0x04
#define RAM_SAVE_FLAG_PAGE 0x08
#define RAM_SAVE_FLAG_EOS 0x10
+#define RAM_SAVE_FLAG_CONTINUE 0x20
static int is_dup_page(uint8_t *page, uint8_t ch)
{
@@ -120,6 +121,7 @@
do {
if (cpu_physical_memory_get_dirty(current_addr, MIGRATION_DIRTY_FLAG)) {
uint8_t *p;
+ int cont = (block == last_block) ? RAM_SAVE_FLAG_CONTINUE : 0;
cpu_physical_memory_reset_dirty(current_addr,
current_addr + TARGET_PAGE_SIZE,
@@ -128,17 +130,21 @@
p = block->host + offset;
if (is_dup_page(p, *p)) {
- qemu_put_be64(f, offset | RAM_SAVE_FLAG_COMPRESS);
- qemu_put_byte(f, strlen(block->idstr));
- qemu_put_buffer(f, (uint8_t *)block->idstr,
- strlen(block->idstr));
+ qemu_put_be64(f, offset | cont | RAM_SAVE_FLAG_COMPRESS);
+ if (!cont) {
+ qemu_put_byte(f, strlen(block->idstr));
+ qemu_put_buffer(f, (uint8_t *)block->idstr,
+ strlen(block->idstr));
+ }
qemu_put_byte(f, *p);
bytes_sent = 1;
} else {
- qemu_put_be64(f, offset | RAM_SAVE_FLAG_PAGE);
- qemu_put_byte(f, strlen(block->idstr));
- qemu_put_buffer(f, (uint8_t *)block->idstr,
- strlen(block->idstr));
+ qemu_put_be64(f, offset | cont | RAM_SAVE_FLAG_PAGE);
+ if (!cont) {
+ qemu_put_byte(f, strlen(block->idstr));
+ qemu_put_buffer(f, (uint8_t *)block->idstr,
+ strlen(block->idstr));
+ }
qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
bytes_sent = TARGET_PAGE_SIZE;
}
@@ -289,6 +295,36 @@
return (stage == 2) && (expected_time <= migrate_max_downtime());
}
+static inline void *host_from_stream_offset(QEMUFile *f,
+ ram_addr_t offset,
+ int flags)
+{
+ static RAMBlock *block = NULL;
+ char id[256];
+ uint8_t len;
+
+ if (flags & RAM_SAVE_FLAG_CONTINUE) {
+ if (!block) {
+ fprintf(stderr, "Ack, bad migration stream!\n");
+ return NULL;
+ }
+
+ return block->host + offset;
+ }
+
+ len = qemu_get_byte(f);
+ qemu_get_buffer(f, (uint8_t *)id, len);
+ id[len] = 0;
+
+ QLIST_FOREACH(block, &ram_list.blocks, next) {
+ if (!strncmp(id, block->idstr, sizeof(id)))
+ return block->host + offset;
+ }
+
+ fprintf(stderr, "Can't find block %s!\n", id);
+ return NULL;
+}
+
int ram_load(QEMUFile *f, void *opaque, int version_id)
{
ram_addr_t addr;
@@ -346,26 +382,11 @@
void *host;
uint8_t ch;
- if (version_id == 3) {
+ if (version_id == 3)
host = qemu_get_ram_ptr(addr);
- } else {
- RAMBlock *block;
- char id[256];
- uint8_t len;
+ else
+ host = host_from_stream_offset(f, addr, flags);
- len = qemu_get_byte(f);
- qemu_get_buffer(f, (uint8_t *)id, len);
- id[len] = 0;
-
- QLIST_FOREACH(block, &ram_list.blocks, next) {
- if (!strncmp(id, block->idstr, sizeof(id)))
- break;
- }
- if (!block)
- return -EINVAL;
-
- host = block->host + addr;
- }
ch = qemu_get_byte(f);
memset(host, ch, TARGET_PAGE_SIZE);
#ifndef _WIN32
@@ -377,26 +398,11 @@
} else if (flags & RAM_SAVE_FLAG_PAGE) {
void *host;
- if (version_id == 3) {
+ if (version_id == 3)
host = qemu_get_ram_ptr(addr);
- } else {
- RAMBlock *block;
- char id[256];
- uint8_t len;
+ else
+ host = host_from_stream_offset(f, addr, flags);
- len = qemu_get_byte(f);
- qemu_get_buffer(f, (uint8_t *)id, len);
- id[len] = 0;
-
- QLIST_FOREACH(block, &ram_list.blocks, next) {
- if (!strncmp(id, block->idstr, sizeof(id)))
- break;
- }
- if (!block)
- return -EINVAL;
-
- host = block->host + addr;
- }
qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
}
if (qemu_file_has_error(f)) {
