#define RAM_SAVE_FLAG_XBZRLE 0x40
/* 0x80 is reserved in migration.h start with 0x100 next */
-
static struct defconfig_file {
const char *filename;
/* Indicates it is an user config file (disabled by -no-user-config) */
{ NULL }, /* end of list */
};
+static const uint8_t ZERO_TARGET_PAGE[TARGET_PAGE_SIZE];
int qemu_read_default_config_files(bool userconfig)
{
uint8_t *encoded_buf;
/* buffer for storing page content */
uint8_t *current_buf;
- /* Cache for XBZRLE */
+ /* Cache for XBZRLE, Protected by lock. */
PageCache *cache;
+ QemuMutex lock;
} XBZRLE = {
.encoded_buf = NULL,
.current_buf = NULL,
/* buffer used for XBZRLE decoding */
static uint8_t *xbzrle_decoded_buf;
+static void XBZRLE_cache_lock(void)
+{
+ if (migrate_use_xbzrle())
+ qemu_mutex_lock(&XBZRLE.lock);
+}
+
+static void XBZRLE_cache_unlock(void)
+{
+ if (migrate_use_xbzrle())
+ qemu_mutex_unlock(&XBZRLE.lock);
+}
+
int64_t xbzrle_cache_resize(int64_t new_size)
{
+ PageCache *new_cache, *cache_to_free;
+
if (new_size < TARGET_PAGE_SIZE) {
return -1;
}
+ /* no need to lock, the current thread holds qemu big lock */
if (XBZRLE.cache != NULL) {
- return cache_resize(XBZRLE.cache, new_size / TARGET_PAGE_SIZE) *
- TARGET_PAGE_SIZE;
+ /* check XBZRLE.cache again later */
+ if (pow2floor(new_size) == migrate_xbzrle_cache_size()) {
+ return pow2floor(new_size);
+ }
+ new_cache = cache_init(new_size / TARGET_PAGE_SIZE,
+ TARGET_PAGE_SIZE);
+ if (!new_cache) {
+ DPRINTF("Error creating cache\n");
+ return -1;
+ }
+
+ XBZRLE_cache_lock();
+ /* the XBZRLE.cache may have be destroyed, check it again */
+ if (XBZRLE.cache != NULL) {
+ cache_to_free = XBZRLE.cache;
+ XBZRLE.cache = new_cache;
+ } else {
+ cache_to_free = new_cache;
+ }
+ XBZRLE_cache_unlock();
+
+ cache_fini(cache_to_free);
}
+
return pow2floor(new_size);
}
return size;
}
+/* This is the last block that we have visited serching for dirty pages
+ */
+static RAMBlock *last_seen_block;
+/* This is the last block from where we have sent data */
+static RAMBlock *last_sent_block;
+static ram_addr_t last_offset;
+static unsigned long *migration_bitmap;
+static uint64_t migration_dirty_pages;
+static uint32_t last_version;
+static bool ram_bulk_stage;
+
+/* Update the xbzrle cache to reflect a page that's been sent as all 0.
+ * The important thing is that a stale (not-yet-0'd) page be replaced
+ * by the new data.
+ * As a bonus, if the page wasn't in the cache it gets added so that
+ * when a small write is made into the 0'd page it gets XBZRLE sent
+ */
+static void xbzrle_cache_zero_page(ram_addr_t current_addr)
+{
+ if (ram_bulk_stage || !migrate_use_xbzrle()) {
+ return;
+ }
+
+ /* We don't care if this fails to allocate a new cache page
+ * as long as it updated an old one */
+ cache_insert(XBZRLE.cache, current_addr, ZERO_TARGET_PAGE);
+}
+
#define ENCODING_FLAG_XBZRLE 0x1
static int save_xbzrle_page(QEMUFile *f, uint8_t *current_data,
return bytes_sent;
}
-
-/* This is the last block that we have visited serching for dirty pages
- */
-static RAMBlock *last_seen_block;
-/* This is the last block from where we have sent data */
-static RAMBlock *last_sent_block;
-static ram_addr_t last_offset;
-static unsigned long *migration_bitmap;
-static uint64_t migration_dirty_pages;
-static uint32_t last_version;
-static bool ram_bulk_stage;
-
static inline
ram_addr_t migration_bitmap_find_and_reset_dirty(MemoryRegion *mr,
ram_addr_t start)
} else {
int ret;
uint8_t *p;
+ bool send_async = true;
int cont = (block == last_sent_block) ?
RAM_SAVE_FLAG_CONTINUE : 0;
ret = ram_control_save_page(f, block->offset,
offset, TARGET_PAGE_SIZE, &bytes_sent);
+ XBZRLE_cache_lock();
+
+ current_addr = block->offset + offset;
if (ret != RAM_SAVE_CONTROL_NOT_SUPP) {
if (ret != RAM_SAVE_CONTROL_DELAYED) {
if (bytes_sent > 0) {
RAM_SAVE_FLAG_COMPRESS);
qemu_put_byte(f, 0);
bytes_sent++;
+ /* Must let xbzrle know, otherwise a previous (now 0'd) cached
+ * page would be stale
+ */
+ xbzrle_cache_zero_page(current_addr);
} else if (!ram_bulk_stage && migrate_use_xbzrle()) {
- current_addr = block->offset + offset;
bytes_sent = save_xbzrle_page(f, p, current_addr, block,
offset, cont, last_stage);
if (!last_stage) {
+ /* We must send exactly what's in the xbzrle cache
+ * even if the page wasn't xbzrle compressed, so that
+ * it's right next time.
+ */
p = get_cached_data(XBZRLE.cache, current_addr);
+
+ /* Can't send this cached data async, since the cache page
+ * might get updated before it gets to the wire
+ */
+ send_async = false;
}
}
/* XBZRLE overflow or normal page */
if (bytes_sent == -1) {
bytes_sent = save_block_hdr(f, block, offset, cont, RAM_SAVE_FLAG_PAGE);
- qemu_put_buffer_async(f, p, TARGET_PAGE_SIZE);
+ if (send_async) {
+ qemu_put_buffer_async(f, p, TARGET_PAGE_SIZE);
+ } else {
+ qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
+ }
bytes_sent += TARGET_PAGE_SIZE;
acct_info.norm_pages++;
}
+ XBZRLE_cache_unlock();
/* if page is unmodified, continue to the next */
if (bytes_sent > 0) {
last_sent_block = block;
migration_bitmap = NULL;
}
+ XBZRLE_cache_lock();
if (XBZRLE.cache) {
cache_fini(XBZRLE.cache);
g_free(XBZRLE.cache);
XBZRLE.encoded_buf = NULL;
XBZRLE.current_buf = NULL;
}
+ XBZRLE_cache_unlock();
}
static void ram_migration_cancel(void *opaque)
dirty_rate_high_cnt = 0;
if (migrate_use_xbzrle()) {
+ qemu_mutex_lock_iothread();
XBZRLE.cache = cache_init(migrate_xbzrle_cache_size() /
TARGET_PAGE_SIZE,
TARGET_PAGE_SIZE);
if (!XBZRLE.cache) {
+ qemu_mutex_unlock_iothread();
DPRINTF("Error creating cache\n");
return -1;
}
+ qemu_mutex_init(&XBZRLE.lock);
+ qemu_mutex_unlock_iothread();
/* We prefer not to abort if there is no memory */
XBZRLE.encoded_buf = g_try_malloc0(TARGET_PAGE_SIZE);
projects / qemu.git / blobdiff