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Re: [PATCH v2 02/16] migration: Correct transferred bytes value


From: Leonardo Brás
Subject: Re: [PATCH v2 02/16] migration: Correct transferred bytes value
Date: Mon, 22 May 2023 23:15:16 -0300
User-agent: Evolution 3.48.1

On Mon, 2023-05-15 at 21:56 +0200, Juan Quintela wrote:
> We forget several places to add to trasferred amount of data.  With
> this fixes I get:
> 
>    qemu_file_transferred() + multifd_bytes == transferred
> 
> The only place whrer this is not true is during devices sending.  But
> going all through the full tree searching for devices that use
> QEMUFile directly is a bit too much.
> 
> Multifd, precopy and xbzrle work as expected. Postocpy still misses 35
> bytes, but searching for them is getting complicated, so I stop here.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  migration/ram.c       | 14 ++++++++++++++
>  migration/savevm.c    | 19 +++++++++++++++++--
>  migration/vmstate.c   |  3 +++
>  migration/meson.build |  2 +-
>  4 files changed, 35 insertions(+), 3 deletions(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index f69d8d42b0..fd5a8db0f8 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -337,6 +337,7 @@ int64_t ramblock_recv_bitmap_send(QEMUFile *file,
>  
>      g_free(le_bitmap);
>  
> +    stat64_add(&mig_stats.transferred, 8 + size + 8);
>      if (qemu_file_get_error(file)) {
>          return qemu_file_get_error(file);
>      }
> @@ -1392,6 +1393,7 @@ static int find_dirty_block(RAMState *rs, 
> PageSearchStatus *pss)
>                      return ret;
>                  }
>                  qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH);
> +                stat64_add(&mig_stats.transferred, 8);
>                  qemu_fflush(f);
>              }
>              /*
> @@ -3020,6 +3022,7 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
>      RAMState **rsp = opaque;
>      RAMBlock *block;
>      int ret;
> +    size_t size = 0;
>  
>      if (compress_threads_save_setup()) {
>          return -1;
> @@ -3038,16 +3041,20 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
>          qemu_put_be64(f, ram_bytes_total_with_ignored()
>                           | RAM_SAVE_FLAG_MEM_SIZE);
>  
> +        size += 8;
>          RAMBLOCK_FOREACH_MIGRATABLE(block) {
>              qemu_put_byte(f, strlen(block->idstr));
>              qemu_put_buffer(f, (uint8_t *)block->idstr, 
> strlen(block->idstr));
>              qemu_put_be64(f, block->used_length);
> +            size += 1 + strlen(block->idstr) + 8;

I was thinking some of them would look better with sizeof()s instead of given
literal number, such as:

size += sizeof(Byte) + strlen(block->idstr) + sizeof(block->used_length);

Maybe too much?

>              if (migrate_postcopy_ram() && block->page_size !=
>                                            qemu_host_page_size) {
>                  qemu_put_be64(f, block->page_size);
> +                size += 8;
>              }
>              if (migrate_ignore_shared()) {
>                  qemu_put_be64(f, block->mr->addr);
> +                size += 8;
>              }
>          }
>      }
> @@ -3064,11 +3071,14 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
>  
>      if (!migrate_multifd_flush_after_each_section()) {
>          qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH);
> +        size += 8;

sizeof(uint64_t) here is probably too much.


Maybe, it would be nice to have qemu_put_* to return the value, and in this
case:

size += qemu_put_be64(...)

What do you think?

Anyway, 

Reviewed-by: Leonardo Bras <leobras@redhat.com>

>      }
>  
>      qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
> +    size += 8;
>      qemu_fflush(f);
>  
> +    stat64_add(&mig_stats.transferred, size);
>      return 0;
>  }
>  
> @@ -3209,6 +3219,7 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
>      RAMState **temp = opaque;
>      RAMState *rs = *temp;
>      int ret = 0;
> +    size_t size = 0;
>  
>      rs->last_stage = !migration_in_colo_state();
>  
> @@ -3253,8 +3264,11 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
>  
>      if (!migrate_multifd_flush_after_each_section()) {
>          qemu_put_be64(f, RAM_SAVE_FLAG_MULTIFD_FLUSH);
> +        size += 8;
>      }
>      qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
> +    size += 8;
> +    stat64_add(&mig_stats.transferred, size);
>      qemu_fflush(f);
>  
>      return 0;
> diff --git a/migration/savevm.c b/migration/savevm.c
> index e33788343a..c7af9050c2 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -952,6 +952,7 @@ static void save_section_header(QEMUFile *f, 
> SaveStateEntry *se,
>      qemu_put_byte(f, section_type);
>      qemu_put_be32(f, se->section_id);
>  
> +    size_t size = 1 + 4;
>      if (section_type == QEMU_VM_SECTION_FULL ||
>          section_type == QEMU_VM_SECTION_START) {
>          /* ID string */
> @@ -961,7 +962,9 @@ static void save_section_header(QEMUFile *f, 
> SaveStateEntry *se,
>  
>          qemu_put_be32(f, se->instance_id);
>          qemu_put_be32(f, se->version_id);
> +        size += 1 + len + 4 + 4;
>      }
> +    stat64_add(&mig_stats.transferred, size);
>  }
>  
>  /*
> @@ -973,6 +976,7 @@ static void save_section_footer(QEMUFile *f, 
> SaveStateEntry *se)
>      if (migrate_get_current()->send_section_footer) {
>          qemu_put_byte(f, QEMU_VM_SECTION_FOOTER);
>          qemu_put_be32(f, se->section_id);
> +        stat64_add(&mig_stats.transferred, 1 + 4);
>      }
>  }
>  
> @@ -1032,6 +1036,7 @@ static void qemu_savevm_command_send(QEMUFile *f,
>      qemu_put_be16(f, (uint16_t)command);
>      qemu_put_be16(f, len);
>      qemu_put_buffer(f, data, len);
> +    stat64_add(&mig_stats.transferred, 1 + 2 + 2 + len);
>      qemu_fflush(f);
>  }
>  
> @@ -1212,11 +1217,13 @@ void qemu_savevm_state_header(QEMUFile *f)
>      trace_savevm_state_header();
>      qemu_put_be32(f, QEMU_VM_FILE_MAGIC);
>      qemu_put_be32(f, QEMU_VM_FILE_VERSION);
> -
> +    size_t size = 4 + 4;
>      if (migrate_get_current()->send_configuration) {
>          qemu_put_byte(f, QEMU_VM_CONFIGURATION);
> +        size += 1;
>          vmstate_save_state(f, &vmstate_configuration, &savevm_state, 0);
>      }
> +    stat64_add(&mig_stats.transferred, size);
>  }
>  
>  bool qemu_savevm_state_guest_unplug_pending(void)
> @@ -1384,6 +1391,7 @@ void qemu_savevm_state_complete_postcopy(QEMUFile *f)
>  {
>      SaveStateEntry *se;
>      int ret;
> +    size_t size = 0;
>  
>      QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
>          if (!se->ops || !se->ops->save_live_complete_postcopy) {
> @@ -1398,7 +1406,7 @@ void qemu_savevm_state_complete_postcopy(QEMUFile *f)
>          /* Section type */
>          qemu_put_byte(f, QEMU_VM_SECTION_END);
>          qemu_put_be32(f, se->section_id);
> -
> +        size += 1 + 4;
>          ret = se->ops->save_live_complete_postcopy(f, se->opaque);
>          trace_savevm_section_end(se->idstr, se->section_id, ret);
>          save_section_footer(f, se);
> @@ -1409,6 +1417,8 @@ void qemu_savevm_state_complete_postcopy(QEMUFile *f)
>      }
>  
>      qemu_put_byte(f, QEMU_VM_EOF);
> +    size += 1;
> +    stat64_add(&mig_stats.transferred, size);
>      qemu_fflush(f);
>  }
>  
> @@ -1484,6 +1494,7 @@ int 
> qemu_savevm_state_complete_precopy_non_iterable(QEMUFile *f,
>      if (!in_postcopy) {
>          /* Postcopy stream will still be going */
>          qemu_put_byte(f, QEMU_VM_EOF);
> +        stat64_add(&mig_stats.transferred, 1);
>      }
>  
>      json_writer_end_array(vmdesc);
> @@ -1664,15 +1675,18 @@ void qemu_savevm_live_state(QEMUFile *f)
>      /* save QEMU_VM_SECTION_END section */
>      qemu_savevm_state_complete_precopy(f, true, false);
>      qemu_put_byte(f, QEMU_VM_EOF);
> +    stat64_add(&mig_stats.transferred, 1);
>  }
>  
>  int qemu_save_device_state(QEMUFile *f)
>  {
>      SaveStateEntry *se;
> +    size_t size = 0;
>  
>      if (!migration_in_colo_state()) {
>          qemu_put_be32(f, QEMU_VM_FILE_MAGIC);
>          qemu_put_be32(f, QEMU_VM_FILE_VERSION);
> +        size = 4 + 4;
>      }
>      cpu_synchronize_all_states();
>  
> @@ -1690,6 +1704,7 @@ int qemu_save_device_state(QEMUFile *f)
>  
>      qemu_put_byte(f, QEMU_VM_EOF);
>  
> +    stat64_add(&mig_stats.transferred, size + 1);
>      return qemu_file_get_error(f);
>  }
>  
> diff --git a/migration/vmstate.c b/migration/vmstate.c
> index af01d54b6f..ee3b70a6a8 100644
> --- a/migration/vmstate.c
> +++ b/migration/vmstate.c
> @@ -12,6 +12,7 @@
>  
>  #include "qemu/osdep.h"
>  #include "migration.h"
> +#include "migration-stats.h"
>  #include "migration/vmstate.h"
>  #include "savevm.h"
>  #include "qapi/qmp/json-writer.h"
> @@ -394,6 +395,7 @@ int vmstate_save_state_v(QEMUFile *f, const 
> VMStateDescription *vmsd,
>                  written_bytes = qemu_file_transferred_fast(f) - old_offset;
>                  vmsd_desc_field_end(vmsd, vmdesc_loop, field, written_bytes, 
> i);
>  
> +                stat64_add(&mig_stats.transferred, written_bytes);
>                  /* Compressed arrays only care about the first element */
>                  if (vmdesc_loop && vmsd_can_compress(field)) {
>                      vmdesc_loop = NULL;
> @@ -517,6 +519,7 @@ static int vmstate_subsection_save(QEMUFile *f, const 
> VMStateDescription *vmsd,
>              qemu_put_byte(f, len);
>              qemu_put_buffer(f, (uint8_t *)vmsdsub->name, len);
>              qemu_put_be32(f, vmsdsub->version_id);
> +            stat64_add(&mig_stats.transferred, 1 + 1 + len + 4);
>              ret = vmstate_save_state(f, vmsdsub, opaque, vmdesc);
>              if (ret) {
>                  return ret;
> diff --git a/migration/meson.build b/migration/meson.build
> index dc8b1daef5..b3d0c537c8 100644
> --- a/migration/meson.build
> +++ b/migration/meson.build
> @@ -1,5 +1,6 @@
>  # Files needed by unit tests
>  migration_files = files(
> +  'migration-stats.c',
>    'page_cache.c',
>    'xbzrle.c',
>    'vmstate-types.c',
> @@ -18,7 +19,6 @@ softmmu_ss.add(files(
>    'fd.c',
>    'global_state.c',
>    'migration-hmp-cmds.c',
> -  'migration-stats.c',
>    'migration.c',
>    'multifd.c',
>    'multifd-zlib.c',




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