migration/dirtyrate: make sample page count configurable

introduce optional sample-pages argument in calc-dirty-rate,
making sample page count per GB configurable so that more
accurate dirtyrate can be calculated.

Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn>
Message-Id: <3103453a3b2796f929269c99a6ad81a9a7f1f405.1623027729.git.huangy81@chinatelecom.cn>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
  Wrapped a couple of long lines

1 files changed, 27 insertions, 4 deletions

diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
index ccb98147e8..2ee3890721 100644
--- a/migration/dirtyrate.c
+++ b/migration/dirtyrate.c
@@ -48,6 +48,12 @@ static bool is_sample_period_valid(int64_t sec)
     return true;
 }
 
+static bool is_sample_pages_valid(int64_t pages)
+{
+    return pages >= MIN_SAMPLE_PAGE_COUNT &&
+           pages <= MAX_SAMPLE_PAGE_COUNT;
+}
+
 static int dirtyrate_set_state(int *state, int old_state, int new_state)
 {
     assert(new_state < DIRTY_RATE_STATUS__MAX);
@@ -72,13 +78,15 @@ static struct DirtyRateInfo *query_dirty_rate_info(void)
     info->status = CalculatingState;
     info->start_time = DirtyStat.start_time;
     info->calc_time = DirtyStat.calc_time;
+    info->sample_pages = DirtyStat.sample_pages;
 
     trace_query_dirty_rate_info(DirtyRateStatus_str(CalculatingState));
 
     return info;
 }
 
-static void init_dirtyrate_stat(int64_t start_time, int64_t calc_time)
+static void init_dirtyrate_stat(int64_t start_time, int64_t calc_time,
+                                uint64_t sample_pages)
 {
     DirtyStat.total_dirty_samples = 0;
     DirtyStat.total_sample_count = 0;
@@ -86,6 +94,7 @@ static void init_dirtyrate_stat(int64_t start_time, int64_t calc_time)
     DirtyStat.dirty_rate = -1;
     DirtyStat.start_time = start_time;
     DirtyStat.calc_time = calc_time;
+    DirtyStat.sample_pages = sample_pages;
 }
 
 static void update_dirtyrate_stat(struct RamblockDirtyInfo *info)
@@ -361,6 +370,7 @@ void *get_dirtyrate_thread(void *arg)
     int ret;
     int64_t start_time;
     int64_t calc_time;
+    uint64_t sample_pages;
 
     ret = dirtyrate_set_state(&CalculatingState, DIRTY_RATE_STATUS_UNSTARTED,
                               DIRTY_RATE_STATUS_MEASURING);
@@ -371,7 +381,8 @@ void *get_dirtyrate_thread(void *arg)
 
     start_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME) / 1000;
     calc_time = config.sample_period_seconds;
-    init_dirtyrate_stat(start_time, calc_time);
+    sample_pages = config.sample_pages_per_gigabytes;
+    init_dirtyrate_stat(start_time, calc_time, sample_pages);
 
     calculate_dirtyrate(config);
 
@@ -383,7 +394,8 @@ void *get_dirtyrate_thread(void *arg)
     return NULL;
 }
 
-void qmp_calc_dirty_rate(int64_t calc_time, Error **errp)
+void qmp_calc_dirty_rate(int64_t calc_time, bool has_sample_pages,
+                         int64_t sample_pages, Error **errp)
 {
     static struct DirtyRateConfig config;
     QemuThread thread;
@@ -404,6 +416,17 @@ void qmp_calc_dirty_rate(int64_t calc_time, Error **errp)
         return;
     }
 
+    if (has_sample_pages) {
+        if (!is_sample_pages_valid(sample_pages)) {
+            error_setg(errp, "sample-pages is out of range[%d, %d].",
+                            MIN_SAMPLE_PAGE_COUNT,
+                            MAX_SAMPLE_PAGE_COUNT);
+            return;
+        }
+    } else {
+        sample_pages = DIRTYRATE_DEFAULT_SAMPLE_PAGES;
+    }
+
     /*
      * Init calculation state as unstarted.
      */
@@ -415,7 +438,7 @@ void qmp_calc_dirty_rate(int64_t calc_time, Error **errp)
     }
 
     config.sample_period_seconds = calc_time;
-    config.sample_pages_per_gigabytes = DIRTYRATE_DEFAULT_SAMPLE_PAGES;
+    config.sample_pages_per_gigabytes = sample_pages;
     qemu_thread_create(&thread, "get_dirtyrate", get_dirtyrate_thread,
                        (void *)&config, QEMU_THREAD_DETACHED);
 }