[PATCH 12/16] migration/multifd: Enable set normal page ratio test hook in multifd.

[Hao Xiang]

Test hook is disabled by default. To set it, a normal page ratio
between 0 and 100 are valid. If the ratio is set to 50, it means
at least 50% of all pages are sent as normal pages.

Signed-off-by: Hao Xiang <hao.xi...@bytedance.com>
---
 include/qemu/dsa.h             |  7 ++++++-
 migration/migration-hmp-cmds.c |  7 +++++++
 migration/multifd.c            | 36 +++++++++++++++++++++++++++++++++-
 3 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/include/qemu/dsa.h b/include/qemu/dsa.h
index 3f8ee07004..bc7f652e0b 100644
--- a/include/qemu/dsa.h
+++ b/include/qemu/dsa.h
@@ -37,7 +37,10 @@ typedef struct buffer_zero_batch_task {
     enum dsa_task_type task_type;
     enum dsa_task_status status;
     bool *results;
-    int batch_size;
+    uint32_t batch_size;
+    // Set normal page ratio test hook.
+    uint32_t normal_page_index;
+    uint32_t normal_page_counter;
     QSIMPLEQ_ENTRY(buffer_zero_batch_task) entry;
 } buffer_zero_batch_task;
 
@@ -45,6 +48,8 @@ typedef struct buffer_zero_batch_task {
 
 struct buffer_zero_batch_task {
     bool *results;
+    uint32_t normal_page_index;
+    uint32_t normal_page_counter;
 };
 
 #endif
diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index bdffe9e023..e1f110afbc 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -351,6 +351,9 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict 
*qdict)
         monitor_printf(mon, "%s: %s\n",
             MigrationParameter_str(MIGRATION_PARAMETER_MULTIFD_DSA_ACCEL),
             params->multifd_dsa_accel);
+        monitor_printf(mon, "%s: %u\n",
+            
MigrationParameter_str(MIGRATION_PARAMETER_MULTIFD_NORMAL_PAGE_RATIO),
+            params->multifd_normal_page_ratio);
 
         if (params->has_block_bitmap_mapping) {
             const BitmapMigrationNodeAliasList *bmnal;
@@ -646,6 +649,10 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict 
*qdict)
         error_setg(&err, "The block-bitmap-mapping parameter can only be set "
                    "through QMP");
         break;
+    case MIGRATION_PARAMETER_MULTIFD_NORMAL_PAGE_RATIO:
+        p->has_multifd_normal_page_ratio = true;
+        visit_type_uint8(v, param, &p->multifd_normal_page_ratio, &err);
+        break;
     case MIGRATION_PARAMETER_X_VCPU_DIRTY_LIMIT_PERIOD:
         p->has_x_vcpu_dirty_limit_period = true;
         visit_type_size(v, param, &p->x_vcpu_dirty_limit_period, &err);
diff --git a/migration/multifd.c b/migration/multifd.c
index 79fecbd3ae..a0bfb48a7e 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -684,6 +684,37 @@ int multifd_send_sync_main(QEMUFile *f)
     return 0;
 }
 
+static void multifd_normal_page_test_hook(MultiFDSendParams *p)
+{
+    /*
+     * The value is between 0 to 100. If the value is 10, it means at
+     * least 10% of the pages are normal page. A zero page can be made
+     * a normal page but not the other way around.
+     */
+    uint8_t multifd_normal_page_ratio =
+        migrate_multifd_normal_page_ratio();
+    struct buffer_zero_batch_task *dsa_batch_task = p->dsa_batch_task;
+
+    // Set normal page test hook is disabled.
+    if (multifd_normal_page_ratio > 100) {
+        return;
+    }
+
+    for (int i = 0; i < p->pages->num; i++) {
+        if (dsa_batch_task->normal_page_counter < multifd_normal_page_ratio) {
+            // Turn a zero page into a normal page.
+            dsa_batch_task->results[i] = false;
+        }
+        dsa_batch_task->normal_page_index++;
+        dsa_batch_task->normal_page_counter++;
+
+        if (dsa_batch_task->normal_page_index >= 100) {
+            dsa_batch_task->normal_page_index = 0;
+            dsa_batch_task->normal_page_counter = 0;
+        }
+    }
+}
+
 static void set_page(MultiFDSendParams *p, bool zero_page, uint64_t offset)
 {
     RAMBlock *rb = p->pages->block;
@@ -704,7 +735,8 @@ static void buffer_is_zero_use_cpu(MultiFDSendParams *p)
     assert(!dsa_is_running());
 
     for (int i = 0; i < p->pages->num; i++) {
-        p->dsa_batch_task->results[i] = buffer_is_zero(buf[i], p->page_size);
+        p->dsa_batch_task->results[i] =
+            buffer_is_zero(buf[i], p->page_size);
     }
 }
 
@@ -737,6 +769,8 @@ static void multifd_zero_page_check(MultiFDSendParams *p)
         buffer_is_zero_use_dsa(p);
     }
 
+    multifd_normal_page_test_hook(p);
+
     for (int i = 0; i < p->pages->num; i++) {
         uint64_t offset = p->pages->offset[i];
         bool zero_page = p->dsa_batch_task->results[i];
-- 
2.30.2