Re: [Qemu-devel] [PATCH 10/11] Add XBZRLE statistics

[Luiz Capitulino <lcapitulino@redhat.com>]

On Tue, 31 Jul 2012 11:31:09 +0300
Orit Wasserman <owasserm@redhat.com> wrote:

> On 07/30/2012 10:37 PM, Luiz Capitulino wrote:
> > On Sun, 29 Jul 2012 12:43:02 +0300
> > Orit Wasserman <owasserm@redhat.com> wrote:
> > 
> >> 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      |   28 ++++++++++++++++++++++++++++
> >>  hmp.c            |   21 +++++++++++++++++++++
> >>  migration.c      |   28 ++++++++++++++++++++++++++++
> >>  migration.h      |    4 ++++
> >>  qapi-schema.json |   32 +++++++++++++++++++++++++++++++-
> >>  qmp-commands.hx  |   35 +++++++++++++++++++++++++++++++++++
> >>  6 files changed, 147 insertions(+), 1 deletions(-)
> >>
> >> diff --git a/arch_init.c b/arch_init.c
> >> index 7f12317..9833d54 100644
> >> --- a/arch_init.c
> >> +++ b/arch_init.c
> >> @@ -203,7 +203,11 @@ int64_t xbzrle_cache_resize(int64_t new_size)
> >>  typedef struct AccountingInfo {
> >>      uint64_t dup_pages;
> >>      uint64_t norm_pages;
> >> +    uint64_t xbzrle_bytes;
> >> +    uint64_t xbzrle_pages;
> >> +    uint64_t xbzrle_cache_miss;
> >>      uint64_t iterations;
> >> +    uint64_t xbzrle_overflows;
> >>  } AccountingInfo;
> >>  
> >>  static AccountingInfo acct_info;
> >> @@ -233,6 +237,26 @@ uint64_t norm_mig_pages_transferred(void)
> >>      return acct_info.norm_pages;
> >>  }
> >>  
> >> +uint64_t xbzrle_mig_bytes_transferred(void)
> >> +{
> >> +    return acct_info.xbzrle_bytes;
> >> +}
> >> +
> >> +uint64_t xbzrle_mig_pages_transferred(void)
> >> +{
> >> +    return acct_info.xbzrle_pages;
> >> +}
> >> +
> >> +uint64_t xbzrle_mig_pages_cache_miss(void)
> >> +{
> >> +    return acct_info.xbzrle_cache_miss;
> >> +}
> >> +
> >> +uint64_t xbzrle_mig_pages_overflow(void)
> >> +{
> >> +    return acct_info.xbzrle_overflows;
> >> +}
> >> +
> >>  static void save_block_hdr(QEMUFile *f, RAMBlock *block, ram_addr_t offset,
> >>          int cont, int flag)
> >>  {
> >> @@ -257,6 +281,7 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t *current_data,
> >>      if (!cache_is_cached(XBZRLE.cache, current_addr)) {
> >>          cache_insert(XBZRLE.cache, current_addr,
> >>                       g_memdup(current_data, TARGET_PAGE_SIZE));
> >> +        acct_info.xbzrle_cache_miss++;
> >>          return -1;
> >>      }
> >>  
> >> @@ -274,6 +299,7 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t *current_data,
> >>          return 0;
> >>      } else if (encoded_len == -1) {
> >>          DPRINTF("Overflow\n");
> >> +        acct_info.xbzrle_overflows++;
> >>          /* update data in the cache */
> >>          memcpy(prev_cached_page, current_data, TARGET_PAGE_SIZE);
> >>          return -1;
> >> @@ -288,6 +314,8 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t *current_data,
> >>      qemu_put_be16(f, encoded_len);
> >>      qemu_put_buffer(f, XBZRLE.encoded_buf, encoded_len);
> >>      bytes_sent = encoded_len + 1 + 2;
> >> +    acct_info.xbzrle_pages++;
> >> +    acct_info.xbzrle_bytes += bytes_sent;
> >>  
> >>      return bytes_sent;
> >>  }
> >> diff --git a/hmp.c b/hmp.c
> >> index 9770d7b..383d5b1 100644
> >> --- a/hmp.c
> >> +++ b/hmp.c
> >> @@ -172,6 +172,27 @@ void hmp_info_migrate(Monitor *mon)
> >>                         info->disk->total >> 10);
> >>      }
> >>  
> >> +    if (info->has_xbzrle_cache) {
> >> +        monitor_printf(mon, "cache size: %" PRIu64 " bytes\n",
> >> +                       info->xbzrle_cache->cache_size);
> >> +        if (info->xbzrle_cache->has_xbzrle_bytes) {
> >> +            monitor_printf(mon, "xbzrle transferred: %" PRIu64 " kbytes\n",
> >> +                           info->xbzrle_cache->xbzrle_bytes >> 10);
> >> +        }
> >> +        if (info->xbzrle_cache->has_xbzrle_pages) {
> >> +            monitor_printf(mon, "xbzrle pages: %" PRIu64 " pages\n",
> >> +                           info->xbzrle_cache->xbzrle_pages);
> >> +        }
> >> +        if (info->xbzrle_cache->has_xbzrle_cache_miss) {
> >> +            monitor_printf(mon, "xbzrle cache miss: %" PRIu64 "\n",
> >> +                           info->xbzrle_cache->xbzrle_cache_miss);
> >> +        }
> >> +        if (info->xbzrle_cache->has_xbzrle_overflow) {
> >> +            monitor_printf(mon, "xbzrle overflow : %" PRIu64 "\n",
> >> +                           info->xbzrle_cache->xbzrle_overflow);
> >> +        }
> >> +    }
> >> +
> >>      qapi_free_MigrationInfo(info);
> >>      qapi_free_MigrationParameters(params);
> >>  }
> >> diff --git a/migration.c b/migration.c
> >> index 4dc99ba..fb802bc 100644
> >> --- a/migration.c
> >> +++ b/migration.c
> >> @@ -136,6 +136,23 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp)
> >>      return params;
> >>  }
> >>  
> >> +static void get_xbzrle_cache_stats(MigrationInfo *info)
> >> +{
> >> +    if (migrate_use_xbzrle()) {
> >> +        info->has_xbzrle_cache = true;
> >> +        info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
> >> +        info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
> >> +        info->xbzrle_cache->has_xbzrle_bytes = true;
> >> +        info->xbzrle_cache->xbzrle_bytes = xbzrle_mig_bytes_transferred();
> >> +        info->xbzrle_cache->has_xbzrle_pages = true;
> >> +        info->xbzrle_cache->xbzrle_pages = xbzrle_mig_pages_transferred();
> >> +        info->xbzrle_cache->has_xbzrle_cache_miss = true;
> >> +        info->xbzrle_cache->xbzrle_cache_miss = xbzrle_mig_pages_cache_miss();
> >> +        info->xbzrle_cache->has_xbzrle_overflow = true;
> >> +        info->xbzrle_cache->xbzrle_overflow = xbzrle_mig_pages_overflow();
> >> +    }
> >> +}
> >> +
> >>  MigrationInfo *qmp_query_migrate(Error **errp)
> >>  {
> >>      MigrationInfo *info = g_malloc0(sizeof(*info));
> >> @@ -144,6 +161,13 @@ MigrationInfo *qmp_query_migrate(Error **errp)
> >>      switch (s->state) {
> >>      case MIG_STATE_SETUP:
> >>          /* no migration has happened ever */
> >> +
> >> +        /* display xbzrle cache size */
> >> +        if (migrate_use_xbzrle()) {
> >> +            info->has_xbzrle_cache = true;
> >> +            info->xbzrle_cache = g_malloc0(sizeof(*info->xbzrle_cache));
> >> +            info->xbzrle_cache->cache_size = migrate_xbzrle_cache_size();
> >> +        }
> > 
> > Is it really useful to return this in MIG_SETUP? Can't the cache size
> > be queried by some query- command?
> I like it this way and it is very simple to use, you need to use query-migrate command if you do migration 
> anyway.

But this will only be returned before a migration takes place. Then it will
never be returned again. Doesn't seem to be the right place for it.

> Otherwise we will need to add a query command for each configurable parameters,
> so one for speed and another for downtime and probably more in the future.

I don't think this is a problem. We're trying to design QMP commands as we
would design a C API, and I'd have different functions to query different things.

Besides, let's not mix what's best to a human user and what's best for a
machine protocol. If we add different query commands for different parameters,
then it's possible to call them from 'info migrate' if you wish.

> This way we use one command to query the migration setup.

Again, that information would only be returned before a first migration
occurs.

> 
> Orit
> > 
> >>          break;
> >>      case MIG_STATE_ACTIVE:
> >>          info->has_status = true;
> >> @@ -166,8 +190,12 @@ MigrationInfo *qmp_query_migrate(Error **errp)
> >>              info->disk->remaining = blk_mig_bytes_remaining();
> >>              info->disk->total = blk_mig_bytes_total();
> >>          }
> >> +
> >> +        get_xbzrle_cache_stats(info);
> >>          break;
> >>      case MIG_STATE_COMPLETED:
> >> +        get_xbzrle_cache_stats(info);
> >> +
> >>          info->has_status = true;
> >>          info->status = g_strdup("completed");
> >>  
> >> diff --git a/migration.h b/migration.h
> >> index e4a7cd7..a9852fc 100644
> >> --- a/migration.h
> >> +++ b/migration.h
> >> @@ -91,6 +91,10 @@ uint64_t dup_mig_bytes_transferred(void);
> >>  uint64_t dup_mig_pages_transferred(void);
> >>  uint64_t norm_mig_bytes_transferred(void);
> >>  uint64_t norm_mig_pages_transferred(void);
> >> +uint64_t xbzrle_mig_bytes_transferred(void);
> >> +uint64_t xbzrle_mig_pages_transferred(void);
> >> +uint64_t xbzrle_mig_pages_overflow(void);
> >> +uint64_t xbzrle_mig_pages_cache_miss(void);
> >>  
> >>  /**
> >>   * @migrate_add_blocker - prevent migration from proceeding
> >> diff --git a/qapi-schema.json b/qapi-schema.json
> >> index a936714..91dee72 100644
> >> --- a/qapi-schema.json
> >> +++ b/qapi-schema.json
> >> @@ -275,6 +275,31 @@
> >>             'total_time': 'int', 'duplicate': 'int', 'normal': 'int' } }
> >>  
> >>  ##
> >> +# @XBZRLECacheStats
> >> +#
> >> +# Detailed XBZRLE migration cache statistics
> >> +#
> >> +# @cache-size: XBZRLE cache size
> >> +#
> >> +# @xbzrle-bytes: @optional, amount of bytes already transferred to the target VM
> >> +#                only returned when migration is active or completed
> > 
> > s/xbzrle-bytes/transferred-bytes
> > 
> >> +#
> >> +# @xbzrle-pages: @optional, amount of pages transferred to the target VM
> >> +#                only returned when migration is active or completed
> > 
> > s/xbzrle-pages/transferred-pages
> > 
> >> +#
> >> +# @xbzrle-cache-miss: @optional, number of cache miss
> >> +#                     only returned when migration is active or completed
> > 
> > s/xbzrle/xbzrle//
> > 
> >> +#
> >> +# @xbzrle-overflow: @optional, number of overflows
> >> +#                   only returned when migration is active or completed
> > 
> > s/xbzrle///
> > 
> > Besides, all these parameters shouldn't be optional as they are unconditionally
> > included (BZRLECacheStats itself is optional as returned by query-migrate).
> > 
> >> +#
> >> +# Since: 1.2
> >> +##
> >> +{ 'type': 'XBZRLECacheStats',
> >> +  'data': {'cache-size': 'int', '*xbzrle-bytes': 'int', '*xbzrle-pages': 'int',
> >> +           '*xbzrle-cache-miss': 'int', '*xbzrle-overflow': 'int' } }
> >> +
> >> +##
> >>  # @MigrationInfo
> >>  #
> >>  # Information about current migration process.
> >> @@ -292,11 +317,16 @@
> >>  #        status, only returned if status is 'active' and it is a block
> >>  #        migration
> >>  #
> >> +# @xbzrle-cache: #optional @XBZRLECacheStats containing detailed XBZRLE
> >> +#                migration statistics, only returned if XBZRLE feature is on
> >> +#                (since 1.2)
> >> +#
> >>  # Since: 0.14.0
> >>  ##
> >>  { 'type': 'MigrationInfo',
> >>    'data': {'*status': 'str', '*ram': 'MigrationStats',
> >> -           '*disk': 'MigrationStats'} }
> >> +           '*disk': 'MigrationStats',
> >> +           '*xbzrle-cache': 'XBZRLECacheStats'} }
> >>  
> >>  ##
> >>  # @query-migrate
> >> diff --git a/qmp-commands.hx b/qmp-commands.hx
> >> index a5a67eb..0546f42 100644
> >> --- a/qmp-commands.hx
> >> +++ b/qmp-commands.hx
> >> @@ -2106,6 +2106,17 @@ The main json-object contains the following:
> >>           - "transferred": amount transferred (json-int)
> >>           - "remaining": amount remaining (json-int)
> >>           - "total": total (json-int)
> >> +- "xbzrle-cache": only present if XBZRLE is active.
> >> +  It is a json-object with the following XBZRLE information:
> >> +         - "cache-size": XBZRLE cache size
> >> +         - "xbzrle-bytes": total XBZRLE bytes transferred, only present if
> >> +                           status is "active" or "completed"
> >> +         - "xbzrle-pages": number of XBZRLE compressed pages, only present if
> >> +                           status is "active" or "completed"
> >> +         - "cache-miss": number of cache misses, only present if
> >> +                           status is "active" or "completed"
> >> +         - "overflow": number of XBZRLE overflows, only present if
> >> +                           status is "active" or "completed"
> >>  Examples:
> >>  
> >>  1. Before the first migration
> >> @@ -2170,6 +2181,30 @@ Examples:
> >>        }
> >>     }
> >>  
> >> +6. Migration is being performed and XBZRLE is active:
> >> +
> >> +-> { "execute": "query-migrate" }
> >> +<- {
> >> +      "return":{
> >> +         "status":"active",
> >> +         "capabilities" : [ { "capability": "xbzrle", "state" : true } ],
> >> +         "ram":{
> >> +            "total":1057024,
> >> +            "remaining":1053304,
> >> +            "transferred":3720,
> >> +            "duplicate": 10,
> >> +            "normal" : 3333
> >> +         },
> >> +         "cache":{
> >> +            "cache-size": 1024
> >> +            "xbzrle-transferred":20971520,
> >> +            "xbzrle-pages":2444343,
> >> +            "xbzrle-cache-miss":2244,
> >> +            "xbzrle-overflow":34434
> >> +         }
> >> +      }
> >> +   }
> >> +
> >>  EQMP
> >>  
> >>      {
> > 
>