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

[David Edmondson]

On Wednesday, 2023-03-01 at 13:40:26 +01, Juan Quintela wrote:
> 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
>
> Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: David Edmondson <david.edmondson@oracle.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 ca9adcb2ad..41fcec73ba 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++) {
-- 
I can't explain, you would not understand. This is not how I am.