This change extends the MigrationStatus interface to track zero pages
and zero bytes counter.

Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>
---
 migration/migration-hmp-cmds.c      |  4 ++++
 migration/migration.c               |  2 ++
 qapi/migration.json                 | 15 ++++++++++++++-
 tests/migration/guestperf/engine.py |  2 ++
 4 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index 7e96ae6ffd..a38ad0255d 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -111,6 +111,10 @@ void hmp_info_migrate(Monitor *mon, const QDict *qdict)
                        info->ram->normal);
         monitor_printf(mon, "normal bytes: %" PRIu64 " kbytes\n",
                        info->ram->normal_bytes >> 10);
+        monitor_printf(mon, "zero pages: %" PRIu64 " pages\n",
+                       info->ram->zero_pages);
+        monitor_printf(mon, "zero bytes: %" PRIu64 " kbytes\n",
+                       info->ram->zero_bytes >> 10);
         monitor_printf(mon, "dirty sync count: %" PRIu64 "\n",
                        info->ram->dirty_sync_count);
         monitor_printf(mon, "page size: %" PRIu64 " kbytes\n",
diff --git a/migration/migration.c b/migration/migration.c
index bab68bcbef..fc4e3ef52d 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1126,6 +1126,8 @@ static void populate_ram_info(MigrationInfo *info, MigrationState *s)
     info->ram->skipped = 0;
     info->ram->normal = stat64_get(&mig_stats.normal_pages);
     info->ram->normal_bytes = info->ram->normal * page_size;
+    info->ram->zero_pages = stat64_get(&mig_stats.zero_pages);
+    info->ram->zero_bytes = info->ram->zero_pages * page_size;
     info->ram->mbps = s->mbps;
     info->ram->dirty_sync_count =
         stat64_get(&mig_stats.dirty_sync_count);
diff --git a/qapi/migration.json b/qapi/migration.json
index ca9561fbf1..03b850bab7 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -63,6 +63,10 @@
 #     between 0 and @dirty-sync-count * @multifd-channels.  (since
 #     7.1)
 #
+# @zero-pages: number of zero pages (since 9.0)
+#
+# @zero-bytes: number of zero bytes sent (since 9.0)
+#
 # Features:
 #
 # @deprecated: Member @skipped is always zero since 1.5.3
@@ -81,7 +85,8 @@
            'multifd-bytes': 'uint64', 'pages-per-second': 'uint64',
            'precopy-bytes': 'uint64', 'downtime-bytes': 'uint64',
            'postcopy-bytes': 'uint64',
-           'dirty-sync-missed-zero-copy': 'uint64' } }
+           'dirty-sync-missed-zero-copy': 'uint64',
+           'zero-pages': 'int', 'zero-bytes': 'size' } }
 
 ##
 # @XBZRLECacheStats:
@@ -332,6 +337,8 @@
 #               "duplicate":123,
 #               "normal":123,
 #               "normal-bytes":123456,
+#               "zero-pages":123,
+#               "zero-bytes":123456,
 #               "dirty-sync-count":15
 #             }
 #          }
@@ -358,6 +365,8 @@
 #                 "duplicate":123,
 #                 "normal":123,
 #                 "normal-bytes":123456,
+#                 "zero-pages":123,
+#                 "zero-bytes":123456,
 #                 "dirty-sync-count":15
 #              }
 #           }
@@ -379,6 +388,8 @@
 #                 "duplicate":123,
 #                 "normal":123,
 #                 "normal-bytes":123456,
+#                 "zero-pages":123,
+#                 "zero-bytes":123456,
 #                 "dirty-sync-count":15
 #              },
 #              "disk":{
@@ -405,6 +416,8 @@
 #                 "duplicate":10,
 #                 "normal":3333,
 #                 "normal-bytes":3412992,
+#                 "zero-pages":3333,
+#                 "zero-bytes":3412992,
 #                 "dirty-sync-count":15
 #              },
 #              "xbzrle-cache":{
diff --git a/tests/migration/guestperf/engine.py b/tests/migration/guestperf/engine.py
index 608d7270f6..693e07c227 100644
--- a/tests/migration/guestperf/engine.py
+++ b/tests/migration/guestperf/engine.py
@@ -92,6 +92,8 @@ def _migrate_progress(self, vm):
                 info["ram"].get("skipped", 0),
                 info["ram"].get("normal", 0),
                 info["ram"].get("normal-bytes", 0),
+                info["ram"].get("zero-pages", 0);
+                info["ram"].get("zero-bytes", 0);
                 info["ram"].get("dirty-pages-rate", 0),
                 info["ram"].get("mbps", 0),
                 info["ram"].get("dirty-sync-count", 0)
-- 
2.30.2

Hao Xiang <hao.xiang@bytedance.com> writes:

> This change extends the MigrationStatus interface to track zero pages
> and zero bytes counter.
>
> Signed-off-by: Hao Xiang <hao.xiang@bytedance.com>

[...]

> diff --git a/qapi/migration.json b/qapi/migration.json
> index ca9561fbf1..03b850bab7 100644
> --- a/qapi/migration.json
> +++ b/qapi/migration.json
> @@ -63,6 +63,10 @@
>  #     between 0 and @dirty-sync-count * @multifd-channels.  (since
>  #     7.1)
>  #
> +# @zero-pages: number of zero pages (since 9.0)
> +#
> +# @zero-bytes: number of zero bytes sent (since 9.0)
> +#

Discussion of v3 has led me to believe:

1. A page is either migrated as a normal page or as a zero page.

2. The following equations hold:

    @normal-bytes = @normal * @page-size

    @zero-bytes = @zero-pages * @page-size

3. @zero-pages is the same as @duplicate, with a better name.  We intend
   to drop @duplicate eventually.

If this is correct, I'd like you to

A. Name it @zero for consistency with @normal.  Disregard my advice to
   name it @zero-pages; two consistent bad names are better than one bad
   name, one good name, and inconsistency.

B. Add @zero and @zero-bytes next to @normal and @normal-bytes.

C. Deprecate @duplicate (item 3).  Separate patch, please.

D. Consider documenting more clearly what normal and zero pages are
   (item 1), and how @FOO, @FOO-pages and @page-size are related (item
   2).  Could be done in a followup patch.

>  # Features:
>  #
>  # @deprecated: Member @skipped is always zero since 1.5.3
> @@ -81,7 +85,8 @@
>             'multifd-bytes': 'uint64', 'pages-per-second': 'uint64',
>             'precopy-bytes': 'uint64', 'downtime-bytes': 'uint64',
>             'postcopy-bytes': 'uint64',
> -           'dirty-sync-missed-zero-copy': 'uint64' } }
> +           'dirty-sync-missed-zero-copy': 'uint64',
> +           'zero-pages': 'int', 'zero-bytes': 'size' } }
>  

[...]