Re: [Qemu-devel] [PATCH 20/22] Add migrate_set_cachesize command

[Luiz Capitulino <lcapitulino@redhat.com>]

On Fri, 13 Jul 2012 09:23:42 +0200
Juan Quintela <quintela@redhat.com> wrote:

> From: Orit Wasserman <owasserm@redhat.com>
> 
> Change XBZRLE cache size in bytes (the size should be a power of 2, it will be
> rounded down to the nearest power of 2).
> If XBZRLE cache size is too small there will be many cache miss.

As far as QMP is concerned:

 Reviewed-by: Luiz Capitulino <lcapitulino@redhat.com>

> 
> Signed-off-by: Benoit Hudzia <benoit.hudzia@sap.com>
> Signed-off-by: Petter Svard <petters@cs.umu.se>
> Signed-off-by: Aidan Shribman <aidan.shribman@sap.com>
> Signed-off-by: Orit Wasserman <owasserm@redhat.com>
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  arch_init.c      |   10 ++++++++++
>  hmp-commands.hx  |   20 ++++++++++++++++++++
>  hmp.c            |   13 +++++++++++++
>  hmp.h            |    1 +
>  migration.c      |   14 ++++++++++++++
>  migration.h      |    2 ++
>  qapi-schema.json |   16 ++++++++++++++++
>  qmp-commands.hx  |   23 +++++++++++++++++++++++
>  8 files changed, 99 insertions(+)
> 
> diff --git a/arch_init.c b/arch_init.c
> index a3a4707..d972d84 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -192,6 +192,16 @@ static struct {
>      .cache = NULL,
>  };
> 
> +
> +int64_t xbzrle_cache_resize(int64_t new_size)
> +{
> +    if (XBZRLE.cache != NULL) {
> +        return cache_resize(XBZRLE.cache, new_size / TARGET_PAGE_SIZE) *
> +            TARGET_PAGE_SIZE;
> +    }
> +    return pow2floor(new_size);
> +}
> +
>  static void save_block_hdr(QEMUFile *f, RAMBlock *block, ram_addr_t offset,
>          int cont, int flag)
>  {
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index 9245bef..052a0a3 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -829,6 +829,26 @@ STEXI
>  @item migrate_cancel
>  @findex migrate_cancel
>  Cancel the current VM migration.
> +
> +ETEXI
> +
> +    {
> +        .name       = "migrate_set_cachesize",
> +        .args_type  = "value:o",
> +        .params     = "value",
> +        .help       = "set cache size (in bytes) for XBZRLE migrations,"
> +                      "the cache size will be rounded down to the nearest "
> +                      "power of 2.\n"
> +                      "The cache size effects the number of cache misses."
> +                      "In case of a high cache miss ratio you need to increase"
> +                      " the cache size",
> +        .mhandler.cmd = hmp_migrate_set_cachesize,
> +    },
> +
> +STEXI
> +@item migrate_set_cachesize @var{value}
> +@findex migrate_set_cachesize
> +Set cache size to @var{value} (in bytes) for xbzrle migrations.
>  ETEXI
> 
>      {
> diff --git a/hmp.c b/hmp.c
> index b0440e6..99ad00a 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -758,6 +758,19 @@ void hmp_migrate_set_downtime(Monitor *mon, const QDict *qdict)
>      qmp_migrate_set_downtime(value, NULL);
>  }
> 
> +void hmp_migrate_set_cachesize(Monitor *mon, const QDict *qdict)
> +{
> +    int64_t value = qdict_get_int(qdict, "value");
> +    Error *err = NULL;
> +
> +    qmp_migrate_set_cache_size(value, &err);
> +    if (err) {
> +        monitor_printf(mon, "%s\n", error_get_pretty(err));
> +        error_free(err);
> +        return;
> +    }
> +}
> +
>  void hmp_migrate_set_speed(Monitor *mon, const QDict *qdict)
>  {
>      int64_t value = qdict_get_int(qdict, "value");
> diff --git a/hmp.h b/hmp.h
> index 09ba198..7c5117d 100644
> --- a/hmp.h
> +++ b/hmp.h
> @@ -53,6 +53,7 @@ void hmp_migrate_cancel(Monitor *mon, const QDict *qdict);
>  void hmp_migrate_set_downtime(Monitor *mon, const QDict *qdict);
>  void hmp_migrate_set_speed(Monitor *mon, const QDict *qdict);
>  void hmp_migrate_set_parameter(Monitor *mon, const QDict *qdict);
> +void hmp_migrate_set_cachesize(Monitor *mon, const QDict *qdict);
>  void hmp_set_password(Monitor *mon, const QDict *qdict);
>  void hmp_expire_password(Monitor *mon, const QDict *qdict);
>  void hmp_eject(Monitor *mon, const QDict *qdict);
> diff --git a/migration.c b/migration.c
> index 1a264a9..d134bf6 100644
> --- a/migration.c
> +++ b/migration.c
> @@ -533,6 +533,20 @@ void qmp_migrate_cancel(Error **errp)
>      migrate_fd_cancel(migrate_get_current());
>  }
> 
> +void qmp_migrate_set_cache_size(int64_t value, Error **errp)
> +{
> +    MigrationState *s = migrate_get_current();
> +
> +    /* Check for truncation */
> +    if (value != (size_t)value) {
> +        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "cache size",
> +                  "exceeding address space");
> +        return;
> +    }
> +
> +    s->xbzrle_cache_size = xbzrle_cache_resize(value);
> +}
> +
>  void qmp_migrate_set_speed(int64_t value, Error **errp)
>  {
>      MigrationState *s;
> diff --git a/migration.h b/migration.h
> index cdf6787..337e225 100644
> --- a/migration.h
> +++ b/migration.h
> @@ -108,4 +108,6 @@ int xbzrle_decode_buffer(uint8_t *src, int slen, uint8_t *dst, int dlen);
>  int migrate_use_xbzrle(void);
>  int64_t migrate_xbzrle_cache_size(void);
> 
> +int64_t xbzrle_cache_resize(int64_t new_size);
> +
>  #endif
> diff --git a/qapi-schema.json b/qapi-schema.json
> index a8408fd..a0f0f95 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -1390,6 +1390,22 @@
>  { 'command': 'migrate_set_speed', 'data': {'value': 'int'} }
> 
>  ##
> +# @migrate-set-cache-size
> +#
> +# Set XBZRLE cache size
> +#
> +# @value: cache size in bytes
> +#
> +# The size will be rounded down to the nearest power of 2.
> +# The cache size can be modified before and during ongoing migration
> +#
> +# Returns: nothing on success
> +#
> +# Since: 1.2
> +##
> +{ 'command': 'migrate-set-cache-size', 'data': {'value': 'int'} }
> +
> +##
>  # @ObjectPropertyInfo:
>  #
>  # @name: the name of the property
> diff --git a/qmp-commands.hx b/qmp-commands.hx
> index 3ee6e00..a3d57ce 100644
> --- a/qmp-commands.hx
> +++ b/qmp-commands.hx
> @@ -520,6 +520,29 @@ Example:
>  <- { "return": {} }
> 
>  EQMP
> +{
> +        .name       = "migrate-set-cache-size",
> +        .args_type  = "value:o",
> +        .mhandler.cmd_new = qmp_marshal_input_migrate_set_cache_size,
> +    },
> +
> +SQMP
> +migrate-set-cache-size
> +---------------------
> +
> +Set cache size to be used by XBZRLE migration, the cache size will be rounded
> +down to the nearest power of 2
> +
> +Arguments:
> +
> +- "value": cache size in bytes (json-int)
> +
> +Example:
> +
> +-> { "execute": "migrate-set-cache-size", "arguments": { "value": 536870912 } }
> +<- { "return": {} }
> +
> +EQMP
> 
>      {
>          .name       = "migrate_set_speed",