Re: [Qemu-devel] [PATCH v8 05/14] migration: introduce postcopy-only pending

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Vladimir Sementsov-Ogievskiy (vsementsov@virtuozzo.com) wrote:
> There would be savevm states (dirty-bitmap) which can migrate only in
> postcopy stage. The corresponding pending is introduced here.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Reviewed-by: Juan Quintela <quintela@redhat.com>

Note the error patchew picked up on this for s390 which has
cmma_save_pending.

Dave

> ---
>  include/migration/register.h | 17 +++++++++++++++--
>  migration/savevm.h           |  5 +++--
>  migration/block.c            |  7 ++++---
>  migration/migration.c        | 15 ++++++++-------
>  migration/ram.c              |  9 +++++----
>  migration/savevm.c           | 13 ++++++++-----
>  migration/trace-events       |  2 +-
>  7 files changed, 44 insertions(+), 24 deletions(-)
> 
> diff --git a/include/migration/register.h b/include/migration/register.h
> index f4f7bdc177..9436a87678 100644
> --- a/include/migration/register.h
> +++ b/include/migration/register.h
> @@ -37,8 +37,21 @@ typedef struct SaveVMHandlers {
>      int (*save_setup)(QEMUFile *f, void *opaque);
>      void (*save_live_pending)(QEMUFile *f, void *opaque,
>                                uint64_t threshold_size,
> -                              uint64_t *non_postcopiable_pending,
> -                              uint64_t *postcopiable_pending);
> +                              uint64_t *res_precopy_only,
> +                              uint64_t *res_compatible,
> +                              uint64_t *res_postcopy_only);
> +    /* Note for save_live_pending:
> +     * - res_precopy_only is for data which must be migrated in precopy phase
> +     *     or in stopped state, in other words - before target vm start
> +     * - res_compatible is for data which may be migrated in any phase
> +     * - res_postcopy_only is for data which must be migrated in postcopy phase
> +     *     or in stopped state, in other words - after source vm stop
> +     *
> +     * Sum of res_postcopy_only, res_compatible and res_postcopy_only is the
> +     * whole amount of pending data.
> +     */
> +
> +
>      LoadStateHandler *load_state;
>      int (*load_setup)(QEMUFile *f, void *opaque);
>      int (*load_cleanup)(void *opaque);
> diff --git a/migration/savevm.h b/migration/savevm.h
> index 295c4a1f2c..cf4f0d37ca 100644
> --- a/migration/savevm.h
> +++ b/migration/savevm.h
> @@ -38,8 +38,9 @@ void qemu_savevm_state_complete_postcopy(QEMUFile *f);
>  int qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only,
>                                         bool inactivate_disks);
>  void qemu_savevm_state_pending(QEMUFile *f, uint64_t max_size,
> -                               uint64_t *res_non_postcopiable,
> -                               uint64_t *res_postcopiable);
> +                               uint64_t *res_precopy_only,
> +                               uint64_t *res_compatible,
> +                               uint64_t *res_postcopy_only);
>  void qemu_savevm_send_ping(QEMUFile *f, uint32_t value);
>  void qemu_savevm_send_open_return_path(QEMUFile *f);
>  int qemu_savevm_send_packaged(QEMUFile *f, const uint8_t *buf, size_t len);
> diff --git a/migration/block.c b/migration/block.c
> index 3282809583..39dfa567e8 100644
> --- a/migration/block.c
> +++ b/migration/block.c
> @@ -865,8 +865,9 @@ static int block_save_complete(QEMUFile *f, void *opaque)
>  }
>  
>  static void block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
> -                               uint64_t *non_postcopiable_pending,
> -                               uint64_t *postcopiable_pending)
> +                               uint64_t *res_precopy_only,
> +                               uint64_t *res_compatible,
> +                               uint64_t *res_postcopy_only)
>  {
>      /* Estimate pending number of bytes to send */
>      uint64_t pending;
> @@ -887,7 +888,7 @@ static void block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
>  
>      DPRINTF("Enter save live pending  %" PRIu64 "\n", pending);
>      /* We don't do postcopy */
> -    *non_postcopiable_pending += pending;
> +    *res_precopy_only += pending;
>  }
>  
>  static int block_load(QEMUFile *f, void *opaque, int version_id)
> diff --git a/migration/migration.c b/migration/migration.c
> index 4de3b551fe..e6c9be3cca 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -2216,20 +2216,21 @@ static void *migration_thread(void *opaque)
>          uint64_t pending_size;
>  
>          if (!qemu_file_rate_limit(s->to_dst_file)) {
> -            uint64_t pend_post, pend_nonpost;
> +            uint64_t pend_pre, pend_compat, pend_post;
>  
> -            qemu_savevm_state_pending(s->to_dst_file, threshold_size,
> -                                      &pend_nonpost, &pend_post);
> -            pending_size = pend_nonpost + pend_post;
> +            qemu_savevm_state_pending(s->to_dst_file, threshold_size, &pend_pre,
> +                                      &pend_compat, &pend_post);
> +            pending_size = pend_pre + pend_compat + pend_post;
>              trace_migrate_pending(pending_size, threshold_size,
> -                                  pend_post, pend_nonpost);
> +                                  pend_pre, pend_compat, pend_post);
>              if (pending_size && pending_size >= threshold_size) {
>                  /* Still a significant amount to transfer */
>  
>                  if (migrate_postcopy() &&
>                      s->state != MIGRATION_STATUS_POSTCOPY_ACTIVE &&
> -                    pend_nonpost <= threshold_size &&
> -                    atomic_read(&s->start_postcopy)) {
> +                    pend_pre <= threshold_size &&
> +                    (atomic_read(&s->start_postcopy) ||
> +                     (pend_pre + pend_compat <= threshold_size))) {
>  
>                      if (!postcopy_start(s, &old_vm_running)) {
>                          current_active_state = MIGRATION_STATUS_POSTCOPY_ACTIVE;
> diff --git a/migration/ram.c b/migration/ram.c
> index 8620aa400a..1b664a2d9a 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -2358,8 +2358,9 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
>  }
>  
>  static void ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
> -                             uint64_t *non_postcopiable_pending,
> -                             uint64_t *postcopiable_pending)
> +                             uint64_t *res_precopy_only,
> +                             uint64_t *res_compatible,
> +                             uint64_t *res_postcopy_only)
>  {
>      RAMState **temp = opaque;
>      RAMState *rs = *temp;
> @@ -2379,9 +2380,9 @@ static void ram_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
>  
>      if (migrate_postcopy_ram()) {
>          /* We can do postcopy, and all the data is postcopiable */
> -        *postcopiable_pending += remaining_size;
> +        *res_compatible += remaining_size;
>      } else {
> -        *non_postcopiable_pending += remaining_size;
> +        *res_precopy_only += remaining_size;
>      }
>  }
>  
> diff --git a/migration/savevm.c b/migration/savevm.c
> index 4a88228614..f6b62cb202 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -1218,13 +1218,15 @@ int qemu_savevm_state_complete_precopy(QEMUFile *f, bool iterable_only,
>   * for units that can't do postcopy.
>   */
>  void qemu_savevm_state_pending(QEMUFile *f, uint64_t threshold_size,
> -                               uint64_t *res_non_postcopiable,
> -                               uint64_t *res_postcopiable)
> +                               uint64_t *res_precopy_only,
> +                               uint64_t *res_compatible,
> +                               uint64_t *res_postcopy_only)
>  {
>      SaveStateEntry *se;
>  
> -    *res_non_postcopiable = 0;
> -    *res_postcopiable = 0;
> +    *res_precopy_only = 0;
> +    *res_compatible = 0;
> +    *res_postcopy_only = 0;
>  
>  
>      QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
> @@ -1237,7 +1239,8 @@ void qemu_savevm_state_pending(QEMUFile *f, uint64_t threshold_size,
>              }
>          }
>          se->ops->save_live_pending(f, se->opaque, threshold_size,
> -                                   res_non_postcopiable, res_postcopiable);
> +                                   res_precopy_only, res_compatible,
> +                                   res_postcopy_only);
>      }
>  }
>  
> diff --git a/migration/trace-events b/migration/trace-events
> index 6f29fcc686..a04fffb877 100644
> --- a/migration/trace-events
> +++ b/migration/trace-events
> @@ -86,7 +86,7 @@ migrate_fd_cleanup(void) ""
>  migrate_fd_error(const char *error_desc) "error=%s"
>  migrate_fd_cancel(void) ""
>  migrate_handle_rp_req_pages(const char *rbname, size_t start, size_t len) "in %s at 0x%zx len 0x%zx"
> -migrate_pending(uint64_t size, uint64_t max, uint64_t post, uint64_t nonpost) "pending size %" PRIu64 " max %" PRIu64 " (post=%" PRIu64 " nonpost=%" PRIu64 ")"
> +migrate_pending(uint64_t size, uint64_t max, uint64_t pre, uint64_t compat, uint64_t post) "pending size %" PRIu64 " max %" PRIu64 " (pre = %" PRIu64 " compat=%" PRIu64 " post=%" PRIu64 ")"
>  migrate_send_rp_message(int msg_type, uint16_t len) "%d: len %d"
>  migration_completion_file_err(void) ""
>  migration_completion_postcopy_end(void) ""
> -- 
> 2.11.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK