Re: [Qemu-devel] [PATCH v5 05/17] migration: Create x-multifd-threads parameter

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

* Juan Quintela (quintela@redhat.com) wrote:
> Indicates the number of threads that we would create.  By default we
> create 2 threads.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Also needs updating DEFINE_PROP stuff - and if Markus' qapi patch lands.

> --
> 
> Catch inconsistent defaults (eric).
> Improve comment stating that number of threads is the same than number
> of sockets
> ---
>  hmp.c                 |  7 +++++++
>  migration/migration.c | 23 +++++++++++++++++++++++
>  migration/migration.h |  1 +
>  qapi-schema.json      | 18 ++++++++++++++++--
>  4 files changed, 47 insertions(+), 2 deletions(-)
> 
> diff --git a/hmp.c b/hmp.c
> index d970ea9..92f9456 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -335,6 +335,9 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict *qdict)
>          monitor_printf(mon, "%s: %s\n",
>              MigrationParameter_lookup[MIGRATION_PARAMETER_BLOCK_INCREMENTAL],
>                         params->block_incremental ? "on" : "off");
> +        monitor_printf(mon, "%s: %" PRId64 "\n",
> +            MigrationParameter_lookup[MIGRATION_PARAMETER_X_MULTIFD_THREADS],
> +            params->x_multifd_threads);
>      }
>  
>      qapi_free_MigrationParameters(params);
> @@ -1573,6 +1576,9 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict)
>                      goto cleanup;
>                  }
>                  p.block_incremental = valuebool;
> +            case MIGRATION_PARAMETER_X_MULTIFD_THREADS:
> +                p.has_x_multifd_threads = true;
> +                use_int_value = true;
>                  break;
>              }
>  
> @@ -1590,6 +1596,7 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict)
>                  p.cpu_throttle_increment = valueint;
>                  p.downtime_limit = valueint;
>                  p.x_checkpoint_delay = valueint;
> +                p.x_multifd_threads = valueint;
>              }
>  
>              qmp_migrate_set_parameters(&p, &err);
> diff --git a/migration/migration.c b/migration/migration.c
> index af2630b..148edc1 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -78,6 +78,7 @@
>   * Note: Please change this default value to 10000 when we support hybrid mode.
>   */
>  #define DEFAULT_MIGRATE_X_CHECKPOINT_DELAY 200
> +#define DEFAULT_MIGRATE_MULTIFD_THREADS 2
>  
>  static NotifierList migration_state_notifiers =
>      NOTIFIER_LIST_INITIALIZER(migration_state_notifiers);
> @@ -460,6 +461,8 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp)
>      params->x_checkpoint_delay = s->parameters.x_checkpoint_delay;
>      params->has_block_incremental = true;
>      params->block_incremental = s->parameters.block_incremental;
> +    params->has_x_multifd_threads = true;
> +    params->x_multifd_threads = s->parameters.x_multifd_threads;
>  
>      return params;
>  }
> @@ -712,6 +715,13 @@ void qmp_migrate_set_parameters(MigrationParameters *params, Error **errp)
>                      "x_checkpoint_delay",
>                      "is invalid, it should be positive");
>      }
> +    if (params->has_x_multifd_threads &&
> +        (params->x_multifd_threads < 1 || params->x_multifd_threads > 255)) {
> +        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
> +                   "multifd_threads",
> +                   "is invalid, it should be in the range of 1 to 255");
> +        return;
> +    }
>  
>      if (params->has_compress_level) {
>          s->parameters.compress_level = params->compress_level;
> @@ -756,6 +766,9 @@ void qmp_migrate_set_parameters(MigrationParameters *params, Error **errp)
>      if (params->has_block_incremental) {
>          s->parameters.block_incremental = params->block_incremental;
>      }
> +    if (params->has_x_multifd_threads) {
> +        s->parameters.x_multifd_threads = params->x_multifd_threads;
> +    }
>  }
>  
>  
> @@ -1291,6 +1304,15 @@ bool migrate_use_multifd(void)
>      return s->enabled_capabilities[MIGRATION_CAPABILITY_X_MULTIFD];
>  }
>  
> +int migrate_multifd_threads(void)
> +{
> +    MigrationState *s;
> +
> +    s = migrate_get_current();
> +
> +    return s->parameters.x_multifd_threads;
> +}
> +
>  int migrate_use_xbzrle(void)
>  {
>      MigrationState *s;
> @@ -2055,6 +2077,7 @@ static void migration_instance_init(Object *obj)
>          .max_bandwidth = MAX_THROTTLE,
>          .downtime_limit = DEFAULT_MIGRATE_SET_DOWNTIME,
>          .x_checkpoint_delay = DEFAULT_MIGRATE_X_CHECKPOINT_DELAY,
> +        .x_multifd_threads = DEFAULT_MIGRATE_MULTIFD_THREADS,
>      };
>      ms->parameters.tls_creds = g_strdup("");
>      ms->parameters.tls_hostname = g_strdup("");
> diff --git a/migration/migration.h b/migration/migration.h
> index 9da9b4e..20ea30c 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -173,6 +173,7 @@ bool migrate_zero_blocks(void);
>  
>  bool migrate_auto_converge(void);
>  bool migrate_use_multifd(void);
> +int migrate_multifd_threads(void);
>  
>  int migrate_use_xbzrle(void);
>  int64_t migrate_xbzrle_cache_size(void);
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 2457fb0..444e8f0 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -902,6 +902,7 @@
>  #
>  # @return-path: If enabled, migration will use the return path even
>  #               for precopy. (since 2.10)
> +#
>  # @x-multifd: Use more than one fd for migration (since 2.10)
>  #
>  # Since: 1.2
> @@ -910,6 +911,7 @@
>    'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',
>             'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',
>             'block', 'return-path', 'x-multifd'] }
> +

Escapee from previous patch.

>  ##
>  # @MigrationCapabilityStatus:
>  #
> @@ -1026,13 +1028,19 @@
>  # 	migrated and the destination must already have access to the
>  # 	same backing chain as was used on the source.  (since 2.10)
>  #
> +# @x-multifd-threads: Number of threads used to migrate data in
> +#                     parallel. This is the same number that the
> +#                     number of sockets used for migration.
> +#                     The default value is 2 (since 2.10)
> +#

That did make me think for a moment; I guess '2' makes sense once you've
set the x-multifd capability on.  The other possibility would be to
remove the capability and just rely on the threads > 1

Dave

>  # Since: 2.4
>  ##
>  { 'enum': 'MigrationParameter',
>    'data': ['compress-level', 'compress-threads', 'decompress-threads',
>             'cpu-throttle-initial', 'cpu-throttle-increment',
>             'tls-creds', 'tls-hostname', 'max-bandwidth',
> -           'downtime-limit', 'x-checkpoint-delay', 'block-incremental' ] }
> +           'downtime-limit', 'x-checkpoint-delay', 'block-incremental',
> +           'x-multifd-threads'] }
>  
>  ##
>  # @migrate-set-parameters:
> @@ -1106,6 +1114,11 @@
>  # 	migrated and the destination must already have access to the
>  # 	same backing chain as was used on the source.  (since 2.10)
>  #
> +# @x-multifd-threads: Number of threads used to migrate data in
> +#                     parallel. This is the same number that the
> +#                     number of sockets used for migration.
> +#                     The default value is 2 (since 2.10)
> +#
>  # Since: 2.4
>  ##
>  { 'struct': 'MigrationParameters',
> @@ -1119,7 +1132,8 @@
>              '*max-bandwidth': 'int',
>              '*downtime-limit': 'int',
>              '*x-checkpoint-delay': 'int',
> -            '*block-incremental': 'bool' } }
> +            '*block-incremental': 'bool',
> +            '*x-multifd-threads': 'int'} }
>  
>  ##
>  # @query-migrate-parameters:
> -- 
> 2.9.4
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK