Re: [PATCH 07/21] migration: Correct transferred bytes value

[Harsh Prateek Bora]

On 5/8/23 18:38, 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

s/whrer/where

> 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/meson.build |  2 +-
>   migration/ram.c       | 14 ++++++++++++++
>   migration/savevm.c    | 19 +++++++++++++++++--
>   migration/vmstate.c   |  3 +++
>   4 files changed, 35 insertions(+), 3 deletions(-)
>
> diff --git a/migration/meson.build b/migration/meson.build
> index da1897fadf..b27fc9eeb6 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',
> @@ -19,7 +20,6 @@ softmmu_ss.add(files(
>     'fd.c',
>     'global_state.c',
>     'migration-hmp-cmds.c',
> -  'migration-stats.c',
>     'migration.c',
>     'multifd.c',
>     'multifd-zlib.c',
> diff --git a/migration/ram.c b/migration/ram.c
> index 5e7bf20ca5..5ae1fdba45 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);

I see lot of hard-coded math like above in below code as well.
Although compiler will do its optimization, but we may choose to write 
it like either of below:
 - sizeof(??) + size + sizeof(??)
 - <macro1> + size + <macro2>
 - size + 16 /* explaining what 8 + 8 means here */
I guess first method or usage of macros instead of hard-coded numbers is 
better. Applies to all instances below.

regards,
Harsh

>       if (qemu_file_get_error(file)) {
>           return qemu_file_get_error(file);
>       }
> @@ -1617,6 +1618,7 @@ 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);
>               }
>               /*
> @@ -3245,6 +3247,7 @@ 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;
> @@ -3263,16 +3266,20 @@ 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;
>               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;
>               }
>           }
>       }
> @@ -3289,11 +3296,14 @@ 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;
>       }
>   
>       qemu_put_be64(f, RAM_SAVE_FLAG_EOS);
> +    size += 8;
>       qemu_fflush(f);
>   
> +    stat64_add(&mig_stats.transferred, size);
>       return 0;
>   }
>   
> @@ -3434,6 +3444,7 @@ 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();
>   
> @@ -3478,8 +3489,11 @@ 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;