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[Qemu-devel] [PATCH] ram: Split dirty bitmap by RAMBlock
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From: |
Juan Quintela |
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Subject: |
[Qemu-devel] [PATCH] ram: Split dirty bitmap by RAMBlock |
|
Date: |
Tue, 25 Apr 2017 12:11:04 +0200 |
Both the ram bitmap and the unsent bitmap are split by RAMBlock.
Signed-off-by: Juan Quintela <address@hidden>
---
include/exec/ram_addr.h | 13 +-
include/migration/postcopy-ram.h | 3 -
migration/postcopy-ram.c | 5 +-
migration/ram.c | 257 +++++++++++++++------------------------
4 files changed, 109 insertions(+), 169 deletions(-)
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index 6436a41..c56b35b 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -39,6 +39,14 @@ struct RAMBlock {
QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers;
int fd;
size_t page_size;
+ /* dirty bitmap used during migration */
+ unsigned long *bmap;
+ /* bitmap of pages that haven't been sent even once
+ * only maintained and used in postcopy at the moment
+ * where it's used to send the dirtymap at the start
+ * of the postcopy phase
+ */
+ unsigned long *unsentmap;
};
static inline bool offset_in_ramblock(RAMBlock *b, ram_addr_t offset)
@@ -360,16 +368,15 @@ static inline void
cpu_physical_memory_clear_dirty_range(ram_addr_t start,
static inline
-uint64_t cpu_physical_memory_sync_dirty_bitmap(unsigned long *dest,
- RAMBlock *rb,
+uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
ram_addr_t start,
ram_addr_t length,
uint64_t *real_dirty_pages)
{
ram_addr_t addr;
- start = rb->offset + start;
unsigned long page = BIT_WORD(start >> TARGET_PAGE_BITS);
uint64_t num_dirty = 0;
+ unsigned long *dest = rb->bmap;
/* start address is aligned at the start of a word? */
if (((page * BITS_PER_LONG) << TARGET_PAGE_BITS) == start) {
diff --git a/include/migration/postcopy-ram.h b/include/migration/postcopy-ram.h
index 8e036b9..4c25f03 100644
--- a/include/migration/postcopy-ram.h
+++ b/include/migration/postcopy-ram.h
@@ -43,12 +43,9 @@ int postcopy_ram_prepare_discard(MigrationIncomingState
*mis);
/*
* Called at the start of each RAMBlock by the bitmap code.
- * 'offset' is the bitmap offset of the named RAMBlock in the migration
- * bitmap.
* Returns a new PDS
*/
PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms,
- unsigned long offset,
const char *name);
/*
diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 85fd8d7..e3f4a37 100644
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -33,7 +33,6 @@
struct PostcopyDiscardState {
const char *ramblock_name;
- uint64_t offset; /* Bitmap entry for the 1st bit of this RAMBlock */
uint16_t cur_entry;
/*
* Start and length of a discard range (bytes)
@@ -717,14 +716,12 @@ void *postcopy_get_tmp_page(MigrationIncomingState *mis)
* returns: a new PDS.
*/
PostcopyDiscardState *postcopy_discard_send_init(MigrationState *ms,
- unsigned long offset,
const char *name)
{
PostcopyDiscardState *res = g_malloc0(sizeof(PostcopyDiscardState));
if (res) {
res->ramblock_name = name;
- res->offset = offset;
}
return res;
@@ -745,7 +742,7 @@ void postcopy_discard_send_range(MigrationState *ms,
PostcopyDiscardState *pds,
{
size_t tp_size = qemu_target_page_size();
/* Convert to byte offsets within the RAM block */
- pds->start_list[pds->cur_entry] = (start - pds->offset) * tp_size;
+ pds->start_list[pds->cur_entry] = start * tp_size;
pds->length_list[pds->cur_entry] = length * tp_size;
trace_postcopy_discard_send_range(pds->ramblock_name, start, length);
pds->cur_entry++;
diff --git a/migration/ram.c b/migration/ram.c
index f48664e..d99f6e2 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -138,19 +138,6 @@ out:
return ret;
}
-struct RAMBitmap {
- struct rcu_head rcu;
- /* Main migration bitmap */
- unsigned long *bmap;
- /* bitmap of pages that haven't been sent even once
- * only maintained and used in postcopy at the moment
- * where it's used to send the dirtymap at the start
- * of the postcopy phase
- */
- unsigned long *unsentmap;
-};
-typedef struct RAMBitmap RAMBitmap;
-
/*
* An outstanding page request, on the source, having been received
* and queued
@@ -220,8 +207,6 @@ struct RAMState {
uint64_t postcopy_requests;
/* protects modification of the bitmap */
QemuMutex bitmap_mutex;
- /* Ram Bitmap protected by RCU */
- RAMBitmap *ram_bitmap;
/* The RAMBlock used in the last src_page_requests */
RAMBlock *last_req_rb;
/* Queue of outstanding page requests from the destination */
@@ -614,22 +599,17 @@ static inline
unsigned long migration_bitmap_find_dirty(RAMState *rs, RAMBlock *rb,
unsigned long start)
{
- unsigned long base = rb->offset >> TARGET_PAGE_BITS;
- unsigned long nr = base + start;
- uint64_t rb_size = rb->used_length;
- unsigned long size = base + (rb_size >> TARGET_PAGE_BITS);
- unsigned long *bitmap;
-
+ unsigned long size = rb->used_length >> TARGET_PAGE_BITS;
+ unsigned long *bitmap = rb->bmap;
unsigned long next;
- bitmap = atomic_rcu_read(&rs->ram_bitmap)->bmap;
- if (rs->ram_bulk_stage && nr > base) {
- next = nr + 1;
+ if (rs->ram_bulk_stage && start > 0) {
+ next = start + 1;
} else {
- next = find_next_bit(bitmap, size, nr);
+ next = find_next_bit(bitmap, size, start);
}
- return next - base;
+ return next;
}
static inline bool migration_bitmap_clear_dirty(RAMState *rs,
@@ -637,10 +617,8 @@ static inline bool migration_bitmap_clear_dirty(RAMState
*rs,
unsigned long page)
{
bool ret;
- unsigned long *bitmap = atomic_rcu_read(&rs->ram_bitmap)->bmap;
- unsigned long nr = (rb->offset >> TARGET_PAGE_BITS) + page;
- ret = test_and_clear_bit(nr, bitmap);
+ ret = test_and_clear_bit(page, rb->bmap);
if (ret) {
rs->migration_dirty_pages--;
@@ -651,10 +629,8 @@ static inline bool migration_bitmap_clear_dirty(RAMState
*rs,
static void migration_bitmap_sync_range(RAMState *rs, RAMBlock *rb,
ram_addr_t start, ram_addr_t length)
{
- unsigned long *bitmap;
- bitmap = atomic_rcu_read(&rs->ram_bitmap)->bmap;
rs->migration_dirty_pages +=
- cpu_physical_memory_sync_dirty_bitmap(bitmap, rb, start, length,
+ cpu_physical_memory_sync_dirty_bitmap(rb, start, length,
&rs->num_dirty_pages_period);
}
@@ -1153,17 +1129,13 @@ static bool get_queued_page(RAMState *rs,
PageSearchStatus *pss)
* search already sent it.
*/
if (block) {
- unsigned long *bitmap;
unsigned long page;
- bitmap = atomic_rcu_read(&rs->ram_bitmap)->bmap;
- page = (block->offset + offset) >> TARGET_PAGE_BITS;
- dirty = test_bit(page, bitmap);
+ page = offset >> TARGET_PAGE_BITS;
+ dirty = test_bit(page, block->bmap);
if (!dirty) {
trace_get_queued_page_not_dirty(block->idstr, (uint64_t)offset,
- page,
- test_bit(page,
- atomic_rcu_read(&rs->ram_bitmap)->unsentmap));
+ page, test_bit(page, block->unsentmap));
} else {
trace_get_queued_page(block->idstr, (uint64_t)offset, page);
}
@@ -1301,16 +1273,13 @@ static int ram_save_target_page(RAMState *rs,
PageSearchStatus *pss,
/* Check the pages is dirty and if it is send it */
if (migration_bitmap_clear_dirty(rs, pss->block, pss->page)) {
- unsigned long *unsentmap;
/*
* If xbzrle is on, stop using the data compression after first
* round of migration even if compression is enabled. In theory,
* xbzrle can do better than compression.
*/
- unsigned long page =
- (pss->block->offset >> TARGET_PAGE_BITS) + pss->page;
- if (migrate_use_compression()
- && (rs->ram_bulk_stage || !migrate_use_xbzrle())) {
+ if (migrate_use_compression() &&
+ (rs->ram_bulk_stage || !migrate_use_xbzrle())) {
res = ram_save_compressed_page(rs, pss, last_stage);
} else {
res = ram_save_page(rs, pss, last_stage);
@@ -1319,9 +1288,8 @@ static int ram_save_target_page(RAMState *rs,
PageSearchStatus *pss,
if (res < 0) {
return res;
}
- unsentmap = atomic_rcu_read(&rs->ram_bitmap)->unsentmap;
- if (unsentmap) {
- clear_bit(page, unsentmap);
+ if (pss->block->unsentmap) {
+ clear_bit(pss->page, pss->block->unsentmap);
}
}
@@ -1451,25 +1419,20 @@ void free_xbzrle_decoded_buf(void)
xbzrle_decoded_buf = NULL;
}
-static void migration_bitmap_free(RAMBitmap *bmap)
-{
- g_free(bmap->bmap);
- g_free(bmap->unsentmap);
- g_free(bmap);
-}
-
static void ram_migration_cleanup(void *opaque)
{
- RAMState *rs = opaque;
+ RAMBlock *block;
/* caller have hold iothread lock or is in a bh, so there is
* no writing race against this migration_bitmap
*/
- RAMBitmap *bitmap = rs->ram_bitmap;
- atomic_rcu_set(&rs->ram_bitmap, NULL);
- if (bitmap) {
- memory_global_dirty_log_stop();
- call_rcu(bitmap, migration_bitmap_free, rcu);
+ memory_global_dirty_log_stop();
+
+ QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
+ g_free(block->bmap);
+ block->bmap = NULL;
+ g_free(block->unsentmap);
+ block->unsentmap = NULL;
}
XBZRLE_cache_lock();
@@ -1504,15 +1467,10 @@ static void ram_state_reset(RAMState *rs)
void ram_debug_dump_bitmap(unsigned long *todump, bool expected)
{
unsigned long ram_pages = last_ram_page();
- RAMState *rs = &ram_state;
int64_t cur;
int64_t linelen = 128;
char linebuf[129];
- if (!todump) {
- todump = atomic_rcu_read(&rs->ram_bitmap)->bmap;
- }
-
for (cur = 0; cur < ram_pages; cur += linelen) {
int64_t curb;
bool found = false;
@@ -1539,14 +1497,12 @@ void ram_debug_dump_bitmap(unsigned long *todump, bool
expected)
void ram_postcopy_migrated_memory_release(MigrationState *ms)
{
- RAMState *rs = &ram_state;
struct RAMBlock *block;
- unsigned long *bitmap = atomic_rcu_read(&rs->ram_bitmap)->bmap;
QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
- unsigned long first = block->offset >> TARGET_PAGE_BITS;
- unsigned long range = first + (block->used_length >> TARGET_PAGE_BITS);
- unsigned long run_start = find_next_zero_bit(bitmap, range, first);
+ unsigned long *bitmap = block->bmap;
+ unsigned long range = block->used_length >> TARGET_PAGE_BITS;
+ unsigned long run_start = find_next_zero_bit(bitmap, range, 0);
while (run_start < range) {
unsigned long run_end = find_next_bit(bitmap, range, run_start +
1);
@@ -1573,16 +1529,13 @@ void
ram_postcopy_migrated_memory_release(MigrationState *ms)
*/
static int postcopy_send_discard_bm_ram(MigrationState *ms,
PostcopyDiscardState *pds,
- unsigned long start,
- unsigned long length)
+ RAMBlock *block)
{
- RAMState *rs = &ram_state;
- unsigned long end = start + length; /* one after the end */
+ unsigned long end = block->used_length >> TARGET_PAGE_BITS;
unsigned long current;
- unsigned long *unsentmap;
+ unsigned long *unsentmap = block->unsentmap;
- unsentmap = atomic_rcu_read(&rs->ram_bitmap)->unsentmap;
- for (current = start; current < end; ) {
+ for (current = 0; current < end; ) {
unsigned long one = find_next_bit(unsentmap, end, current);
if (one <= end) {
@@ -1625,18 +1578,15 @@ static int
postcopy_each_ram_send_discard(MigrationState *ms)
int ret;
QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
- unsigned long first = block->offset >> TARGET_PAGE_BITS;
- PostcopyDiscardState *pds = postcopy_discard_send_init(ms,
- first,
- block->idstr);
+ PostcopyDiscardState *pds =
+ postcopy_discard_send_init(ms, block->idstr);
/*
* Postcopy sends chunks of bitmap over the wire, but it
* just needs indexes at this point, avoids it having
* target page specific code.
*/
- ret = postcopy_send_discard_bm_ram(ms, pds, first,
- block->used_length >> TARGET_PAGE_BITS);
+ ret = postcopy_send_discard_bm_ram(ms, pds, block);
postcopy_discard_send_finish(ms, pds);
if (ret) {
return ret;
@@ -1667,12 +1617,10 @@ static void
postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
PostcopyDiscardState *pds)
{
RAMState *rs = &ram_state;
- unsigned long *bitmap;
- unsigned long *unsentmap;
+ unsigned long *bitmap = block->bmap;
+ unsigned long *unsentmap = block->unsentmap;
unsigned int host_ratio = block->page_size / TARGET_PAGE_SIZE;
- unsigned long first = block->offset >> TARGET_PAGE_BITS;
- unsigned long len = block->used_length >> TARGET_PAGE_BITS;
- unsigned long last = first + (len - 1);
+ unsigned long pages = block->used_length >> TARGET_PAGE_BITS;
unsigned long run_start;
if (block->page_size == TARGET_PAGE_SIZE) {
@@ -1680,18 +1628,15 @@ static void
postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
return;
}
- bitmap = atomic_rcu_read(&rs->ram_bitmap)->bmap;
- unsentmap = atomic_rcu_read(&rs->ram_bitmap)->unsentmap;
-
if (unsent_pass) {
/* Find a sent page */
- run_start = find_next_zero_bit(unsentmap, last + 1, first);
+ run_start = find_next_zero_bit(unsentmap, pages, 0);
} else {
/* Find a dirty page */
- run_start = find_next_bit(bitmap, last + 1, first);
+ run_start = find_next_bit(bitmap, pages, 0);
}
- while (run_start <= last) {
+ while (run_start < pages) {
bool do_fixup = false;
unsigned long fixup_start_addr;
unsigned long host_offset;
@@ -1711,9 +1656,9 @@ static void postcopy_chunk_hostpages_pass(MigrationState
*ms, bool unsent_pass,
/* Find the end of this run */
unsigned long run_end;
if (unsent_pass) {
- run_end = find_next_bit(unsentmap, last + 1, run_start + 1);
+ run_end = find_next_bit(unsentmap, pages, run_start + 1);
} else {
- run_end = find_next_zero_bit(bitmap, last + 1, run_start + 1);
+ run_end = find_next_zero_bit(bitmap, pages, run_start + 1);
}
/*
* If the end isn't at the start of a host page, then the
@@ -1770,11 +1715,10 @@ static void
postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
if (unsent_pass) {
/* Find the next sent page for the next iteration */
- run_start = find_next_zero_bit(unsentmap, last + 1,
- run_start);
+ run_start = find_next_zero_bit(unsentmap, pages, run_start);
} else {
/* Find the next dirty page for the next iteration */
- run_start = find_next_bit(bitmap, last + 1, run_start);
+ run_start = find_next_bit(bitmap, pages, run_start);
}
}
}
@@ -1791,34 +1735,22 @@ static void
postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,
* Returns zero on success
*
* @ms: current migration state
+ * @block: block we want to work with
*/
-static int postcopy_chunk_hostpages(MigrationState *ms)
+static int postcopy_chunk_hostpages(MigrationState *ms, RAMBlock *block)
{
- RAMState *rs = &ram_state;
- struct RAMBlock *block;
-
- /* Easiest way to make sure we don't resume in the middle of a host-page */
- rs->last_seen_block = NULL;
- rs->last_sent_block = NULL;
- rs->last_page = 0;
-
- QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
- unsigned long first = block->offset >> TARGET_PAGE_BITS;
-
- PostcopyDiscardState *pds =
- postcopy_discard_send_init(ms, first, block->idstr);
-
- /* First pass: Discard all partially sent host pages */
- postcopy_chunk_hostpages_pass(ms, true, block, pds);
- /*
- * Second pass: Ensure that all partially dirty host pages are made
- * fully dirty.
- */
- postcopy_chunk_hostpages_pass(ms, false, block, pds);
-
- postcopy_discard_send_finish(ms, pds);
- } /* ram_list loop */
-
+ PostcopyDiscardState *pds =
+ postcopy_discard_send_init(ms, block->idstr);
+
+ /* First pass: Discard all partially sent host pages */
+ postcopy_chunk_hostpages_pass(ms, true, block, pds);
+ /*
+ * Second pass: Ensure that all partially dirty host pages are made
+ * fully dirty.
+ */
+ postcopy_chunk_hostpages_pass(ms, false, block, pds);
+
+ postcopy_discard_send_finish(ms, pds);
return 0;
}
@@ -1836,43 +1768,49 @@ static int postcopy_chunk_hostpages(MigrationState *ms)
* Hopefully this is pretty sparse
*
* @ms: current migration state
- */
+ * @block: block that contains the page we want to canonicalize */
int ram_postcopy_send_discard_bitmap(MigrationState *ms)
{
RAMState *rs = &ram_state;
+ RAMBlock *block;
int ret;
- unsigned long *bitmap, *unsentmap;
rcu_read_lock();
/* This should be our last sync, the src is now paused */
migration_bitmap_sync(rs);
- unsentmap = atomic_rcu_read(&rs->ram_bitmap)->unsentmap;
- if (!unsentmap) {
- /* We don't have a safe way to resize the sentmap, so
- * if the bitmap was resized it will be NULL at this
- * point.
+ /* Easiest way to make sure we don't resume in the middle of a host-page */
+ rs->last_seen_block = NULL;
+ rs->last_sent_block = NULL;
+ rs->last_page = 0;
+
+ QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
+ unsigned long pages = block->used_length >> TARGET_PAGE_BITS;
+ unsigned long *bitmap = block->bmap;
+ unsigned long *unsentmap = block->unsentmap;
+
+ if (!unsentmap) {
+ /* We don't have a safe way to resize the sentmap, so
+ * if the bitmap was resized it will be NULL at this
+ * point.
+ */
+ error_report("migration ram resized during precopy phase");
+ rcu_read_unlock();
+ return -EINVAL;
+ }
+ /* Deal with TPS != HPS and huge pages */
+ ret = postcopy_chunk_hostpages(ms, block);
+ if (ret) {
+ rcu_read_unlock();
+ return ret;
+ }
+
+ /*
+ * Update the unsentmap to be unsentmap = unsentmap | dirty
*/
- error_report("migration ram resized during precopy phase");
- rcu_read_unlock();
- return -EINVAL;
+ bitmap_or(unsentmap, unsentmap, bitmap, pages);
}
-
- /* Deal with TPS != HPS and huge pages */
- ret = postcopy_chunk_hostpages(ms);
- if (ret) {
- rcu_read_unlock();
- return ret;
- }
-
- /*
- * Update the unsentmap to be unsentmap = unsentmap | dirty
- */
- bitmap = atomic_rcu_read(&rs->ram_bitmap)->bmap;
- bitmap_or(unsentmap, unsentmap, bitmap, last_ram_page());
-
-
trace_ram_postcopy_send_discard_bitmap();
#ifdef DEBUG_POSTCOPY
ram_debug_dump_bitmap(unsentmap, true);
@@ -1918,8 +1856,6 @@ err:
static int ram_state_init(RAMState *rs)
{
- unsigned long ram_bitmap_pages;
-
memset(rs, 0, sizeof(*rs));
qemu_mutex_init(&rs->bitmap_mutex);
qemu_mutex_init(&rs->src_page_req_mutex);
@@ -1961,16 +1897,19 @@ static int ram_state_init(RAMState *rs)
rcu_read_lock();
ram_state_reset(rs);
- rs->ram_bitmap = g_new0(RAMBitmap, 1);
/* Skip setting bitmap if there is no RAM */
if (ram_bytes_total()) {
- ram_bitmap_pages = last_ram_page();
- rs->ram_bitmap->bmap = bitmap_new(ram_bitmap_pages);
- bitmap_set(rs->ram_bitmap->bmap, 0, ram_bitmap_pages);
+ RAMBlock *block;
- if (migrate_postcopy_ram()) {
- rs->ram_bitmap->unsentmap = bitmap_new(ram_bitmap_pages);
- bitmap_set(rs->ram_bitmap->unsentmap, 0, ram_bitmap_pages);
+ QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
+ unsigned long pages = block->max_length >> TARGET_PAGE_BITS;
+
+ block->bmap = bitmap_new(pages);
+ bitmap_set(block->bmap, 0, pages);
+ if (migrate_postcopy_ram()) {
+ block->unsentmap = bitmap_new(pages);
+ bitmap_set(block->unsentmap, 0, pages);
+ }
}
}
--
2.9.3