[PATCH v2 0/3] Migration: Make more ram_counters atomic

[PATCH v2 0/3] Migration: Make more ram_counters atomic

[Juan Quintela]

Hi

In v2:
- fix typos found by David Edmondson
- Add review-by tags.

Please review.

[v1]
On previous series we cerate ram_atomic_counters.  But we basically
need that all counters are atomic.  So move back to only have
ram_counters, just with a new type that allows the atomic counters.

Once there, move update of stats out of RAM mutex.
And make multifd_bytes atomic.

Later, Juan.

Juan Quintela (3):
  migration: Merge ram_counters and ram_atomic_counters
  migration: Update atomic stats out of the mutex
  migration: Make multifd_bytes atomic

 migration/ram.h       | 26 ++++++++++++++------------
 migration/migration.c | 12 ++++++------
 migration/multifd.c   |  8 ++++----
 migration/ram.c       | 39 ++++++++++++++++-----------------------
 4 files changed, 40 insertions(+), 45 deletions(-)

-- 
2.39.2

[PATCH v2 1/3] migration: Merge ram_counters and ram_atomic_counters

[Juan Quintela]

Using MgrationStats as type for ram_counters mean that we didn't have
to re-declare each value in another struct. The need of atomic
counters have make us to create MigrationAtomicStats for this atomic
counters.

Create RAMStats type which is a merge of MigrationStats and
MigrationAtomicStats removing unused members.

Signed-off-by: Juan Quintela <quintela@redhat.com>

---

Fix typos found by David Edmondson
---
 migration/ram.h       | 26 ++++++++++++++------------
 migration/migration.c |  8 ++++----
 migration/multifd.c   |  4 ++--
 migration/ram.c       | 39 ++++++++++++++++-----------------------
 4 files changed, 36 insertions(+), 41 deletions(-)

diff --git a/migration/ram.h b/migration/ram.h
index 81cbb0947c..64fb92ccd4 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -35,25 +35,27 @@
 #include "qemu/stats64.h"
 
 /*
- * These are the migration statistic counters that need to be updated using
- * atomic ops (can be accessed by more than one thread).  Here since we
- * cannot modify MigrationStats directly to use Stat64 as it was defined in
- * the QAPI scheme, we define an internal structure to hold them, and we
- * propagate the real values when QMP queries happen.
- *
- * IOW, the corresponding fields within ram_counters on these specific
- * fields will be always zero and not being used at all; they're just
- * placeholders to make it QAPI-compatible.
+ * These are the ram migration statistic counters.  It is loosely
+ * based on MigrationStats.  We change to Stat64 any counter that
+ * needs to be updated using atomic ops (can be accessed by more than
+ * one thread).
  */
 typedef struct {
     Stat64 transferred;
     Stat64 duplicate;
     Stat64 normal;
     Stat64 postcopy_bytes;
-} MigrationAtomicStats;
+    int64_t remaining;
+    int64_t dirty_pages_rate;
+    int64_t dirty_sync_count;
+    int64_t postcopy_requests;
+    uint64_t multifd_bytes;
+    uint64_t precopy_bytes;
+    uint64_t downtime_bytes;
+    uint64_t dirty_sync_missed_zero_copy;
+} RAMStats;
 
-extern MigrationAtomicStats ram_atomic_counters;
-extern MigrationStats ram_counters;
+extern RAMStats ram_counters;
 extern XBZRLECacheStats xbzrle_counters;
 extern CompressionStats compression_counters;
 
diff --git a/migration/migration.c b/migration/migration.c
index ae2025d9d8..923f4762f4 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1140,12 +1140,12 @@ static void populate_ram_info(MigrationInfo *info, MigrationState *s)
     size_t page_size = qemu_target_page_size();
 
     info->ram = g_malloc0(sizeof(*info->ram));
-    info->ram->transferred = stat64_get(&ram_atomic_counters.transferred);
+    info->ram->transferred = stat64_get(&ram_counters.transferred);
     info->ram->total = ram_bytes_total();
-    info->ram->duplicate = stat64_get(&ram_atomic_counters.duplicate);
+    info->ram->duplicate = stat64_get(&ram_counters.duplicate);
     /* legacy value.  It is not used anymore */
     info->ram->skipped = 0;
-    info->ram->normal = stat64_get(&ram_atomic_counters.normal);
+    info->ram->normal = stat64_get(&ram_counters.normal);
     info->ram->normal_bytes = info->ram->normal * page_size;
     info->ram->mbps = s->mbps;
     info->ram->dirty_sync_count = ram_counters.dirty_sync_count;
@@ -1157,7 +1157,7 @@ static void populate_ram_info(MigrationInfo *info, MigrationState *s)
     info->ram->pages_per_second = s->pages_per_second;
     info->ram->precopy_bytes = ram_counters.precopy_bytes;
     info->ram->downtime_bytes = ram_counters.downtime_bytes;
-    info->ram->postcopy_bytes = stat64_get(&ram_atomic_counters.postcopy_bytes);
+    info->ram->postcopy_bytes = stat64_get(&ram_counters.postcopy_bytes);
 
     if (migrate_use_xbzrle()) {
         info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
diff --git a/migration/multifd.c b/migration/multifd.c
index 5e85c3ea9b..7cb2326d03 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -433,7 +433,7 @@ static int multifd_send_pages(QEMUFile *f)
     transferred = ((uint64_t) pages->num) * p->page_size + p->packet_len;
     qemu_file_acct_rate_limit(f, transferred);
     ram_counters.multifd_bytes += transferred;
-    stat64_add(&ram_atomic_counters.transferred, transferred);
+    stat64_add(&ram_counters.transferred, transferred);
     qemu_mutex_unlock(&p->mutex);
     qemu_sem_post(&p->sem);
 
@@ -628,7 +628,7 @@ int multifd_send_sync_main(QEMUFile *f)
         p->pending_job++;
         qemu_file_acct_rate_limit(f, p->packet_len);
         ram_counters.multifd_bytes += p->packet_len;
-        stat64_add(&ram_atomic_counters.transferred, p->packet_len);
+        stat64_add(&ram_counters.transferred, p->packet_len);
         qemu_mutex_unlock(&p->mutex);
         qemu_sem_post(&p->sem);
     }
diff --git a/migration/ram.c b/migration/ram.c
index 96e8a19a58..af749b369b 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -458,25 +458,18 @@ uint64_t ram_bytes_remaining(void)
                        0;
 }
 
-/*
- * NOTE: not all stats in ram_counters are used in reality.  See comments
- * for struct MigrationAtomicStats.  The ultimate result of ram migration
- * counters will be a merged version with both ram_counters and the atomic
- * fields in ram_atomic_counters.
- */
-MigrationStats ram_counters;
-MigrationAtomicStats ram_atomic_counters;
+RAMStats ram_counters;
 
 void ram_transferred_add(uint64_t bytes)
 {
     if (runstate_is_running()) {
         ram_counters.precopy_bytes += bytes;
     } else if (migration_in_postcopy()) {
-        stat64_add(&ram_atomic_counters.postcopy_bytes, bytes);
+        stat64_add(&ram_counters.postcopy_bytes, bytes);
     } else {
         ram_counters.downtime_bytes += bytes;
     }
-    stat64_add(&ram_atomic_counters.transferred, bytes);
+    stat64_add(&ram_counters.transferred, bytes);
 }
 
 void dirty_sync_missed_zero_copy(void)
@@ -757,7 +750,7 @@ void mig_throttle_counter_reset(void)
 
     rs->time_last_bitmap_sync = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
     rs->num_dirty_pages_period = 0;
-    rs->bytes_xfer_prev = stat64_get(&ram_atomic_counters.transferred);
+    rs->bytes_xfer_prev = stat64_get(&ram_counters.transferred);
 }
 
 /**
@@ -1131,8 +1124,8 @@ uint64_t ram_pagesize_summary(void)
 
 uint64_t ram_get_total_transferred_pages(void)
 {
-    return  stat64_get(&ram_atomic_counters.normal) +
-        stat64_get(&ram_atomic_counters.duplicate) +
+    return stat64_get(&ram_counters.normal) +
+        stat64_get(&ram_counters.duplicate) +
         compression_counters.pages + xbzrle_counters.pages;
 }
 
@@ -1193,7 +1186,7 @@ static void migration_trigger_throttle(RAMState *rs)
     MigrationState *s = migrate_get_current();
     uint64_t threshold = s->parameters.throttle_trigger_threshold;
     uint64_t bytes_xfer_period =
-        stat64_get(&ram_atomic_counters.transferred) - rs->bytes_xfer_prev;
+        stat64_get(&ram_counters.transferred) - rs->bytes_xfer_prev;
     uint64_t bytes_dirty_period = rs->num_dirty_pages_period * TARGET_PAGE_SIZE;
     uint64_t bytes_dirty_threshold = bytes_xfer_period * threshold / 100;
 
@@ -1256,7 +1249,7 @@ static void migration_bitmap_sync(RAMState *rs)
         /* reset period counters */
         rs->time_last_bitmap_sync = end_time;
         rs->num_dirty_pages_period = 0;
-        rs->bytes_xfer_prev = stat64_get(&ram_atomic_counters.transferred);
+        rs->bytes_xfer_prev = stat64_get(&ram_counters.transferred);
     }
     if (migrate_use_events()) {
         qapi_event_send_migration_pass(ram_counters.dirty_sync_count);
@@ -1333,7 +1326,7 @@ static int save_zero_page(PageSearchStatus *pss, RAMBlock *block,
     int len = save_zero_page_to_file(pss, block, offset);
 
     if (len) {
-        stat64_add(&ram_atomic_counters.duplicate, 1);
+        stat64_add(&ram_counters.duplicate, 1);
         ram_transferred_add(len);
         return 1;
     }
@@ -1370,9 +1363,9 @@ static bool control_save_page(PageSearchStatus *pss, RAMBlock *block,
     }
 
     if (bytes_xmit > 0) {
-        stat64_add(&ram_atomic_counters.normal, 1);
+        stat64_add(&ram_counters.normal, 1);
     } else if (bytes_xmit == 0) {
-        stat64_add(&ram_atomic_counters.duplicate, 1);
+        stat64_add(&ram_counters.duplicate, 1);
     }
 
     return true;
@@ -1404,7 +1397,7 @@ static int save_normal_page(PageSearchStatus *pss, RAMBlock *block,
         qemu_put_buffer(file, buf, TARGET_PAGE_SIZE);
     }
     ram_transferred_add(TARGET_PAGE_SIZE);
-    stat64_add(&ram_atomic_counters.normal, 1);
+    stat64_add(&ram_counters.normal, 1);
     return 1;
 }
 
@@ -1460,7 +1453,7 @@ static int ram_save_multifd_page(QEMUFile *file, RAMBlock *block,
     if (multifd_queue_page(file, block, offset) < 0) {
         return -1;
     }
-    stat64_add(&ram_atomic_counters.normal, 1);
+    stat64_add(&ram_counters.normal, 1);
 
     return 1;
 }
@@ -1499,7 +1492,7 @@ update_compress_thread_counts(const CompressParam *param, int bytes_xmit)
     ram_transferred_add(bytes_xmit);
 
     if (param->zero_page) {
-        stat64_add(&ram_atomic_counters.duplicate, 1);
+        stat64_add(&ram_counters.duplicate, 1);
         return;
     }
 
@@ -2634,9 +2627,9 @@ void acct_update_position(QEMUFile *f, size_t size, bool zero)
     uint64_t pages = size / TARGET_PAGE_SIZE;
 
     if (zero) {
-        stat64_add(&ram_atomic_counters.duplicate, pages);
+        stat64_add(&ram_counters.duplicate, pages);
     } else {
-        stat64_add(&ram_atomic_counters.normal, pages);
+        stat64_add(&ram_counters.normal, pages);
         ram_transferred_add(size);
         qemu_file_credit_transfer(f, size);
     }
-- 
2.39.2

Re: [PATCH v2 1/3] migration: Merge ram_counters and ram_atomic_counters

[David Edmondson]

Juan Quintela <quintela@redhat.com> writes:

> Using MgrationStats as type for ram_counters mean that we didn't have

Minor typo - MigrationStatus.

> to re-declare each value in another struct. The need of atomic
> counters have make us to create MigrationAtomicStats for this atomic
> counters.
>
> Create RAMStats type which is a merge of MigrationStats and
> MigrationAtomicStats removing unused members.
>
> Signed-off-by: Juan Quintela <quintela@redhat.com>
>
> ---
>
> Fix typos found by David Edmondson
> ---
>  migration/ram.h       | 26 ++++++++++++++------------
>  migration/migration.c |  8 ++++----
>  migration/multifd.c   |  4 ++--
>  migration/ram.c       | 39 ++++++++++++++++-----------------------
>  4 files changed, 36 insertions(+), 41 deletions(-)
>
> diff --git a/migration/ram.h b/migration/ram.h
> index 81cbb0947c..64fb92ccd4 100644
> --- a/migration/ram.h
> +++ b/migration/ram.h
> @@ -35,25 +35,27 @@
>  #include "qemu/stats64.h"
>  
>  /*
> - * These are the migration statistic counters that need to be updated using
> - * atomic ops (can be accessed by more than one thread).  Here since we
> - * cannot modify MigrationStats directly to use Stat64 as it was defined in
> - * the QAPI scheme, we define an internal structure to hold them, and we
> - * propagate the real values when QMP queries happen.
> - *
> - * IOW, the corresponding fields within ram_counters on these specific
> - * fields will be always zero and not being used at all; they're just
> - * placeholders to make it QAPI-compatible.
> + * These are the ram migration statistic counters.  It is loosely
> + * based on MigrationStats.  We change to Stat64 any counter that

Given that the comment should reflect the final state rather than any
progression, how about:

"We use Stat64 for any counter..."

> + * needs to be updated using atomic ops (can be accessed by more than
> + * one thread).
>   */
>  typedef struct {
>      Stat64 transferred;
>      Stat64 duplicate;
>      Stat64 normal;
>      Stat64 postcopy_bytes;
> -} MigrationAtomicStats;
> +    int64_t remaining;
> +    int64_t dirty_pages_rate;
> +    int64_t dirty_sync_count;
> +    int64_t postcopy_requests;
> +    uint64_t multifd_bytes;
> +    uint64_t precopy_bytes;
> +    uint64_t downtime_bytes;
> +    uint64_t dirty_sync_missed_zero_copy;
> +} RAMStats;
>  
> -extern MigrationAtomicStats ram_atomic_counters;
> -extern MigrationStats ram_counters;
> +extern RAMStats ram_counters;
>  extern XBZRLECacheStats xbzrle_counters;
>  extern CompressionStats compression_counters;
>  
> diff --git a/migration/migration.c b/migration/migration.c
> index ae2025d9d8..923f4762f4 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -1140,12 +1140,12 @@ static void populate_ram_info(MigrationInfo *info, MigrationState *s)
>      size_t page_size = qemu_target_page_size();
>  
>      info->ram = g_malloc0(sizeof(*info->ram));
> -    info->ram->transferred = stat64_get(&ram_atomic_counters.transferred);
> +    info->ram->transferred = stat64_get(&ram_counters.transferred);
>      info->ram->total = ram_bytes_total();
> -    info->ram->duplicate = stat64_get(&ram_atomic_counters.duplicate);
> +    info->ram->duplicate = stat64_get(&ram_counters.duplicate);
>      /* legacy value.  It is not used anymore */
>      info->ram->skipped = 0;
> -    info->ram->normal = stat64_get(&ram_atomic_counters.normal);
> +    info->ram->normal = stat64_get(&ram_counters.normal);
>      info->ram->normal_bytes = info->ram->normal * page_size;
>      info->ram->mbps = s->mbps;
>      info->ram->dirty_sync_count = ram_counters.dirty_sync_count;
> @@ -1157,7 +1157,7 @@ static void populate_ram_info(MigrationInfo *info, MigrationState *s)
>      info->ram->pages_per_second = s->pages_per_second;
>      info->ram->precopy_bytes = ram_counters.precopy_bytes;
>      info->ram->downtime_bytes = ram_counters.downtime_bytes;
> -    info->ram->postcopy_bytes = stat64_get(&ram_atomic_counters.postcopy_bytes);
> +    info->ram->postcopy_bytes = stat64_get(&ram_counters.postcopy_bytes);
>  
>      if (migrate_use_xbzrle()) {
>          info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
> diff --git a/migration/multifd.c b/migration/multifd.c
> index 5e85c3ea9b..7cb2326d03 100644
> --- a/migration/multifd.c
> +++ b/migration/multifd.c
> @@ -433,7 +433,7 @@ static int multifd_send_pages(QEMUFile *f)
>      transferred = ((uint64_t) pages->num) * p->page_size + p->packet_len;
>      qemu_file_acct_rate_limit(f, transferred);
>      ram_counters.multifd_bytes += transferred;
> -    stat64_add(&ram_atomic_counters.transferred, transferred);
> +    stat64_add(&ram_counters.transferred, transferred);
>      qemu_mutex_unlock(&p->mutex);
>      qemu_sem_post(&p->sem);
>  
> @@ -628,7 +628,7 @@ int multifd_send_sync_main(QEMUFile *f)
>          p->pending_job++;
>          qemu_file_acct_rate_limit(f, p->packet_len);
>          ram_counters.multifd_bytes += p->packet_len;
> -        stat64_add(&ram_atomic_counters.transferred, p->packet_len);
> +        stat64_add(&ram_counters.transferred, p->packet_len);
>          qemu_mutex_unlock(&p->mutex);
>          qemu_sem_post(&p->sem);
>      }
> diff --git a/migration/ram.c b/migration/ram.c
> index 96e8a19a58..af749b369b 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -458,25 +458,18 @@ uint64_t ram_bytes_remaining(void)
>                         0;
>  }
>  
> -/*
> - * NOTE: not all stats in ram_counters are used in reality.  See comments
> - * for struct MigrationAtomicStats.  The ultimate result of ram migration
> - * counters will be a merged version with both ram_counters and the atomic
> - * fields in ram_atomic_counters.
> - */
> -MigrationStats ram_counters;
> -MigrationAtomicStats ram_atomic_counters;
> +RAMStats ram_counters;
>  
>  void ram_transferred_add(uint64_t bytes)
>  {
>      if (runstate_is_running()) {
>          ram_counters.precopy_bytes += bytes;
>      } else if (migration_in_postcopy()) {
> -        stat64_add(&ram_atomic_counters.postcopy_bytes, bytes);
> +        stat64_add(&ram_counters.postcopy_bytes, bytes);
>      } else {
>          ram_counters.downtime_bytes += bytes;
>      }
> -    stat64_add(&ram_atomic_counters.transferred, bytes);
> +    stat64_add(&ram_counters.transferred, bytes);
>  }
>  
>  void dirty_sync_missed_zero_copy(void)
> @@ -757,7 +750,7 @@ void mig_throttle_counter_reset(void)
>  
>      rs->time_last_bitmap_sync = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
>      rs->num_dirty_pages_period = 0;
> -    rs->bytes_xfer_prev = stat64_get(&ram_atomic_counters.transferred);
> +    rs->bytes_xfer_prev = stat64_get(&ram_counters.transferred);
>  }
>  
>  /**
> @@ -1131,8 +1124,8 @@ uint64_t ram_pagesize_summary(void)
>  
>  uint64_t ram_get_total_transferred_pages(void)
>  {
> -    return  stat64_get(&ram_atomic_counters.normal) +
> -        stat64_get(&ram_atomic_counters.duplicate) +
> +    return stat64_get(&ram_counters.normal) +
> +        stat64_get(&ram_counters.duplicate) +
>          compression_counters.pages + xbzrle_counters.pages;
>  }
>  
> @@ -1193,7 +1186,7 @@ static void migration_trigger_throttle(RAMState *rs)
>      MigrationState *s = migrate_get_current();
>      uint64_t threshold = s->parameters.throttle_trigger_threshold;
>      uint64_t bytes_xfer_period =
> -        stat64_get(&ram_atomic_counters.transferred) - rs->bytes_xfer_prev;
> +        stat64_get(&ram_counters.transferred) - rs->bytes_xfer_prev;
>      uint64_t bytes_dirty_period = rs->num_dirty_pages_period * TARGET_PAGE_SIZE;
>      uint64_t bytes_dirty_threshold = bytes_xfer_period * threshold / 100;
>  
> @@ -1256,7 +1249,7 @@ static void migration_bitmap_sync(RAMState *rs)
>          /* reset period counters */
>          rs->time_last_bitmap_sync = end_time;
>          rs->num_dirty_pages_period = 0;
> -        rs->bytes_xfer_prev = stat64_get(&ram_atomic_counters.transferred);
> +        rs->bytes_xfer_prev = stat64_get(&ram_counters.transferred);
>      }
>      if (migrate_use_events()) {
>          qapi_event_send_migration_pass(ram_counters.dirty_sync_count);
> @@ -1333,7 +1326,7 @@ static int save_zero_page(PageSearchStatus *pss, RAMBlock *block,
>      int len = save_zero_page_to_file(pss, block, offset);
>  
>      if (len) {
> -        stat64_add(&ram_atomic_counters.duplicate, 1);
> +        stat64_add(&ram_counters.duplicate, 1);
>          ram_transferred_add(len);
>          return 1;
>      }
> @@ -1370,9 +1363,9 @@ static bool control_save_page(PageSearchStatus *pss, RAMBlock *block,
>      }
>  
>      if (bytes_xmit > 0) {
> -        stat64_add(&ram_atomic_counters.normal, 1);
> +        stat64_add(&ram_counters.normal, 1);
>      } else if (bytes_xmit == 0) {
> -        stat64_add(&ram_atomic_counters.duplicate, 1);
> +        stat64_add(&ram_counters.duplicate, 1);
>      }
>  
>      return true;
> @@ -1404,7 +1397,7 @@ static int save_normal_page(PageSearchStatus *pss, RAMBlock *block,
>          qemu_put_buffer(file, buf, TARGET_PAGE_SIZE);
>      }
>      ram_transferred_add(TARGET_PAGE_SIZE);
> -    stat64_add(&ram_atomic_counters.normal, 1);
> +    stat64_add(&ram_counters.normal, 1);
>      return 1;
>  }
>  
> @@ -1460,7 +1453,7 @@ static int ram_save_multifd_page(QEMUFile *file, RAMBlock *block,
>      if (multifd_queue_page(file, block, offset) < 0) {
>          return -1;
>      }
> -    stat64_add(&ram_atomic_counters.normal, 1);
> +    stat64_add(&ram_counters.normal, 1);
>  
>      return 1;
>  }
> @@ -1499,7 +1492,7 @@ update_compress_thread_counts(const CompressParam *param, int bytes_xmit)
>      ram_transferred_add(bytes_xmit);
>  
>      if (param->zero_page) {
> -        stat64_add(&ram_atomic_counters.duplicate, 1);
> +        stat64_add(&ram_counters.duplicate, 1);
>          return;
>      }
>  
> @@ -2634,9 +2627,9 @@ void acct_update_position(QEMUFile *f, size_t size, bool zero)
>      uint64_t pages = size / TARGET_PAGE_SIZE;
>  
>      if (zero) {
> -        stat64_add(&ram_atomic_counters.duplicate, pages);
> +        stat64_add(&ram_counters.duplicate, pages);
>      } else {
> -        stat64_add(&ram_atomic_counters.normal, pages);
> +        stat64_add(&ram_counters.normal, pages);
>          ram_transferred_add(size);
>          qemu_file_credit_transfer(f, size);
>      }
> -- 
> 2.39.2

[PATCH v2 2/3] migration: Update atomic stats out of the mutex

[Juan Quintela]

Reviewed-by: David Edmondson <david.edmondson@oracle.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 migration/multifd.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/migration/multifd.c b/migration/multifd.c
index 7cb2326d03..f558169e37 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -433,8 +433,8 @@ static int multifd_send_pages(QEMUFile *f)
     transferred = ((uint64_t) pages->num) * p->page_size + p->packet_len;
     qemu_file_acct_rate_limit(f, transferred);
     ram_counters.multifd_bytes += transferred;
+    qemu_mutex_unlock(&p->mutex);
     stat64_add(&ram_counters.transferred, transferred);
-    qemu_mutex_unlock(&p->mutex);
     qemu_sem_post(&p->sem);
 
     return 1;
@@ -628,8 +628,8 @@ int multifd_send_sync_main(QEMUFile *f)
         p->pending_job++;
         qemu_file_acct_rate_limit(f, p->packet_len);
         ram_counters.multifd_bytes += p->packet_len;
+        qemu_mutex_unlock(&p->mutex);
         stat64_add(&ram_counters.transferred, p->packet_len);
-        qemu_mutex_unlock(&p->mutex);
         qemu_sem_post(&p->sem);
     }
     for (i = 0; i < migrate_multifd_channels(); i++) {
-- 
2.39.2

[PATCH v2 3/3] migration: Make multifd_bytes atomic

[Juan Quintela]

In the spirit of:

commit 394d323bc3451e4d07f13341cb8817fac8dfbadd
Author: Peter Xu <peterx@redhat.com>
Date:   Tue Oct 11 17:55:51 2022 -0400

    migration: Use atomic ops properly for page accountings

Reviewed-by: David Edmondson <david.edmondson@oracle.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 migration/ram.h       | 2 +-
 migration/migration.c | 4 ++--
 migration/multifd.c   | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/migration/ram.h b/migration/ram.h
index 64fb92ccd4..6a3498c732 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -45,11 +45,11 @@ typedef struct {
     Stat64 duplicate;
     Stat64 normal;
     Stat64 postcopy_bytes;
+    Stat64 multifd_bytes;
     int64_t remaining;
     int64_t dirty_pages_rate;
     int64_t dirty_sync_count;
     int64_t postcopy_requests;
-    uint64_t multifd_bytes;
     uint64_t precopy_bytes;
     uint64_t downtime_bytes;
     uint64_t dirty_sync_missed_zero_copy;
diff --git a/migration/migration.c b/migration/migration.c
index 923f4762f4..ca52c8aab3 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1153,7 +1153,7 @@ static void populate_ram_info(MigrationInfo *info, MigrationState *s)
             ram_counters.dirty_sync_missed_zero_copy;
     info->ram->postcopy_requests = ram_counters.postcopy_requests;
     info->ram->page_size = page_size;
-    info->ram->multifd_bytes = ram_counters.multifd_bytes;
+    info->ram->multifd_bytes = stat64_get(&ram_counters.multifd_bytes);
     info->ram->pages_per_second = s->pages_per_second;
     info->ram->precopy_bytes = ram_counters.precopy_bytes;
     info->ram->downtime_bytes = ram_counters.downtime_bytes;
@@ -3774,7 +3774,7 @@ static MigThrError migration_detect_error(MigrationState *s)
 static uint64_t migration_total_bytes(MigrationState *s)
 {
     return qemu_file_total_transferred(s->to_dst_file) +
-        ram_counters.multifd_bytes;
+        stat64_get(&ram_counters.multifd_bytes);
 }
 
 static void migration_calculate_complete(MigrationState *s)
diff --git a/migration/multifd.c b/migration/multifd.c
index f558169e37..91552d33bf 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -432,9 +432,9 @@ static int multifd_send_pages(QEMUFile *f)
     p->pages = pages;
     transferred = ((uint64_t) pages->num) * p->page_size + p->packet_len;
     qemu_file_acct_rate_limit(f, transferred);
-    ram_counters.multifd_bytes += transferred;
     qemu_mutex_unlock(&p->mutex);
     stat64_add(&ram_counters.transferred, transferred);
+    stat64_add(&ram_counters.multifd_bytes, transferred);
     qemu_sem_post(&p->sem);
 
     return 1;
@@ -627,9 +627,9 @@ int multifd_send_sync_main(QEMUFile *f)
         p->flags |= MULTIFD_FLAG_SYNC;
         p->pending_job++;
         qemu_file_acct_rate_limit(f, p->packet_len);
-        ram_counters.multifd_bytes += p->packet_len;
         qemu_mutex_unlock(&p->mutex);
         stat64_add(&ram_counters.transferred, p->packet_len);
+        stat64_add(&ram_counters.multifd_bytes, p->packet_len);
         qemu_sem_post(&p->sem);
     }
     for (i = 0; i < migrate_multifd_channels(); i++) {
-- 
2.39.2