Supply the migration_bitmap_sync function along with the
background argument. Introduce the sync_mode global variable
to track the sync mode and support background sync while
keeping backward compatibility.
Signed-off-by: Hyman Huang <yong.hu...@smartx.com>
---
include/exec/ram_addr.h | 107 +++++++++++++++++++++++++++++++++++++---
migration/ram.c | 53 ++++++++++++++++----
2 files changed, 144 insertions(+), 16 deletions(-)
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index 891c44cf2d..d0d123ac60 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -472,17 +472,68 @@ static inline void
cpu_physical_memory_clear_dirty_range(ram_addr_t start,
cpu_physical_memory_test_and_clear_dirty(start, length, DIRTY_MEMORY_CODE);
}
+static void ramblock_clear_iter_bmap(RAMBlock *rb,
+ ram_addr_t start,
+ ram_addr_t length)
+{
+ ram_addr_t addr;
+ unsigned long *bmap = rb->bmap;
+ unsigned long *shadow_bmap = rb->shadow_bmap;
+ unsigned long *iter_bmap = rb->iter_bmap;
+
+ for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
+ long k = (start + addr) >> TARGET_PAGE_BITS;
+ if (test_bit(k, shadow_bmap) && !test_bit(k, bmap)) {
+ /* Page has been sent, clear the iter bmap */
+ clear_bit(k, iter_bmap);
+ }
+ }
+}
+
+static void ramblock_update_iter_bmap(RAMBlock *rb,
+ ram_addr_t start,
+ ram_addr_t length)
+{
+ ram_addr_t addr;
+ unsigned long *bmap = rb->bmap;
+ unsigned long *iter_bmap = rb->iter_bmap;
+
+ for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
+ long k = (start + addr) >> TARGET_PAGE_BITS;
+ if (test_bit(k, iter_bmap)) {
+ if (!test_bit(k, bmap)) {
+ set_bit(k, bmap);
+ rb->iter_dirty_pages++;
+ }
+ }
+ }
+}
/* Called with RCU critical section */
static inline
uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
ram_addr_t start,
- ram_addr_t length)
+ ram_addr_t length,
+ unsigned int flag)
{
ram_addr_t addr;
unsigned long word = BIT_WORD((start + rb->offset) >> TARGET_PAGE_BITS);
uint64_t num_dirty = 0;
unsigned long *dest = rb->bmap;
+ unsigned long *shadow_bmap = rb->shadow_bmap;
+ unsigned long *iter_bmap = rb->iter_bmap;
+
+ assert(flag && !(flag & (~RAMBLOCK_SYN_MASK)));
+
+ /*
+ * We must remove the sent dirty page from the iter_bmap in order to
+ * minimize redundant page transfers if background sync has appeared
+ * during this iteration.
+ */
+ if (rb->background_sync_shown_up &&
+ (flag & (RAMBLOCK_SYN_MODERN_ITER | RAMBLOCK_SYN_MODERN_BACKGROUND))) {
+ ramblock_clear_iter_bmap(rb, start, length);
+ }
/* start address and length is aligned at the start of a word? */
if (((word * BITS_PER_LONG) << TARGET_PAGE_BITS) ==
@@ -503,8 +554,20 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock
*rb,
if (src[idx][offset]) {
unsigned long bits = qatomic_xchg(&src[idx][offset], 0);
unsigned long new_dirty;
+ if (flag & (RAMBLOCK_SYN_MODERN_ITER |
+ RAMBLOCK_SYN_MODERN_BACKGROUND)) {
+ /* Back-up bmap for the next iteration */
+ iter_bmap[k] |= bits;
+ if (flag == RAMBLOCK_SYN_MODERN_BACKGROUND) {
+ /* Back-up bmap to detect pages has been sent */
+ shadow_bmap[k] = dest[k];
+ }
+ }
new_dirty = ~dest[k];
- dest[k] |= bits;
+ if (flag == RAMBLOCK_SYN_LEGACY_ITER) {
+ dest[k] |= bits;
+ }
+
new_dirty &= bits;
num_dirty += ctpopl(new_dirty);
}
@@ -534,18 +597,50 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock
*rb,
ram_addr_t offset = rb->offset;
for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
- if (cpu_physical_memory_test_and_clear_dirty(
+ bool dirty = false;
+ long k = (start + addr) >> TARGET_PAGE_BITS;
+ if (flag == RAMBLOCK_SYN_MODERN_BACKGROUND) {
+ if (test_bit(k, dest)) {
+ /* Back-up bmap to detect pages has been sent */
+ set_bit(k, shadow_bmap);
+ }
+ }
+
+ dirty = cpu_physical_memory_test_and_clear_dirty(
start + addr + offset,
TARGET_PAGE_SIZE,
- DIRTY_MEMORY_MIGRATION)) {
- long k = (start + addr) >> TARGET_PAGE_BITS;
- if (!test_and_set_bit(k, dest)) {
+ DIRTY_MEMORY_MIGRATION);
+
+ if (flag == RAMBLOCK_SYN_LEGACY_ITER) {
+ if (dirty && !test_and_set_bit(k, dest)) {
num_dirty++;
}
+ } else {
+ if (dirty) {
+ if (!test_bit(k, dest)) {
+ num_dirty++;
+ }
+ /* Back-up bmap for the next iteration */
+ set_bit(k, iter_bmap);
+ }
}
}
}
+ /*
+ * We have to re-fetch dirty pages from the iter_bmap one by one.
+ * It's possible that not all of the dirty pages that meant to
+ * send in the current iteration are included in the bitmap
+ * that the current sync retrieved from the KVM.
+ */
+ if (flag == RAMBLOCK_SYN_MODERN_ITER) {
+ ramblock_update_iter_bmap(rb, start, length);
+ }
+
+ if (flag == RAMBLOCK_SYN_MODERN_BACKGROUND) {
+ rb->background_sync_shown_up = true;
+ }
+
return num_dirty;
}
#endif
diff --git a/migration/ram.c b/migration/ram.c
index f29faa82d6..e205806a5f 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -112,6 +112,8 @@
XBZRLECacheStats xbzrle_counters;
+static RAMBlockSynMode sync_mode = RAMBLOCK_SYN_LEGACY;
+
/* used by the search for pages to send */
struct PageSearchStatus {
/* The migration channel used for a specific host page */
@@ -912,13 +914,42 @@ bool ramblock_page_is_discarded(RAMBlock *rb, ram_addr_t
start)
return false;
}
+static void ramblock_reset_iter_stats(RAMBlock *rb)
+{
+ bitmap_clear(rb->shadow_bmap, 0, rb->used_length >> TARGET_PAGE_BITS);
+ bitmap_clear(rb->iter_bmap, 0, rb->used_length >> TARGET_PAGE_BITS);
+ rb->iter_dirty_pages = 0;
+ rb->background_sync_shown_up = false;
+}
+
/* Called with RCU critical section */
-static void ramblock_sync_dirty_bitmap(RAMState *rs, RAMBlock *rb)
+static void ramblock_sync_dirty_bitmap(RAMState *rs,
+ RAMBlock *rb,
+ bool background)
{
- uint64_t new_dirty_pages =
- cpu_physical_memory_sync_dirty_bitmap(rb, 0, rb->used_length);
+ uint64_t new_dirty_pages;
+ unsigned int flag = RAMBLOCK_SYN_LEGACY_ITER;
+
+ if (sync_mode == RAMBLOCK_SYN_MODERN) {
+ if (background) {
+ flag = RAMBLOCK_SYN_MODERN_BACKGROUND;
+ } else {
+ flag = RAMBLOCK_SYN_MODERN_ITER;
+ }
+ }
+
+ new_dirty_pages =
+ cpu_physical_memory_sync_dirty_bitmap(rb, 0, rb->used_length, flag);
+
+ if (flag & (RAMBLOCK_SYN_LEGACY_ITER | RAMBLOCK_SYN_MODERN_ITER)) {
+ if (flag == RAMBLOCK_SYN_LEGACY_ITER) {
+ rs->migration_dirty_pages += new_dirty_pages;
+ } else {
+ rs->migration_dirty_pages += rb->iter_dirty_pages;
+ ramblock_reset_iter_stats(rb);
+ }
+ }
- rs->migration_dirty_pages += new_dirty_pages;
rs->num_dirty_pages_period += new_dirty_pages;
}
@@ -1041,7 +1072,9 @@ static void migration_trigger_throttle(RAMState *rs)
}
}
-static void migration_bitmap_sync(RAMState *rs, bool last_stage)
+static void migration_bitmap_sync(RAMState *rs,
+ bool last_stage,
+ bool background)
{
RAMBlock *block;
int64_t end_time;
@@ -1058,7 +1091,7 @@ static void migration_bitmap_sync(RAMState *rs, bool
last_stage)
WITH_QEMU_LOCK_GUARD(&rs->bitmap_mutex) {
WITH_RCU_READ_LOCK_GUARD() {
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
- ramblock_sync_dirty_bitmap(rs, block);
+ ramblock_sync_dirty_bitmap(rs, block, background);
}
stat64_set(&mig_stats.dirty_bytes_last_sync,
ram_bytes_remaining());
}
@@ -1101,7 +1134,7 @@ static void migration_bitmap_sync_precopy(RAMState *rs,
bool last_stage)
local_err = NULL;
}
- migration_bitmap_sync(rs, last_stage);
+ migration_bitmap_sync(rs, last_stage, false);
if (precopy_notify(PRECOPY_NOTIFY_AFTER_BITMAP_SYNC, &local_err)) {
error_report_err(local_err);
@@ -2594,7 +2627,7 @@ void ram_postcopy_send_discard_bitmap(MigrationState *ms)
RCU_READ_LOCK_GUARD();
/* This should be our last sync, the src is now paused */
- migration_bitmap_sync(rs, false);
+ migration_bitmap_sync(rs, false, false);
/* Easiest way to make sure we don't resume in the middle of a host-page */
rs->pss[RAM_CHANNEL_PRECOPY].last_sent_block = NULL;
@@ -3581,7 +3614,7 @@ void colo_incoming_start_dirty_log(void)
memory_global_dirty_log_sync(false);
WITH_RCU_READ_LOCK_GUARD() {
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
- ramblock_sync_dirty_bitmap(ram_state, block);
+ ramblock_sync_dirty_bitmap(ram_state, block, false);
/* Discard this dirty bitmap record */
bitmap_zero(block->bmap, block->max_length >> TARGET_PAGE_BITS);
}
@@ -3862,7 +3895,7 @@ void colo_flush_ram_cache(void)
qemu_mutex_lock(&ram_state->bitmap_mutex);
WITH_RCU_READ_LOCK_GUARD() {
RAMBLOCK_FOREACH_NOT_IGNORED(block) {
- ramblock_sync_dirty_bitmap(ram_state, block);
+ ramblock_sync_dirty_bitmap(ram_state, block, false);
}
}
--
2.39.1
