[RFC PATCH 6/8] migration/dirtyrate: Implement get_sample_gap_period() and block_sample_gap_period()

[Chuan Zheng <zhengchuan@huawei.com>]

From: Zheng Chuan <zhengchuan@huawei.com>

Implement get_sample_gap_period() and block_sample_gap_period() to
sleep specific time between sample actions.

Signed-off-by: Zheng Chuan <zhengchuan@huawei.com>
Signed-off-by: YanYing Zhang <ann.zhuangyanying@huawei.com>
---
 migration/dirtyrate.c | 28 ++++++++++++++++++++++++++++
 migration/dirtyrate.h |  6 +++++-
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
index 7badc53..00abfa7 100644
--- a/migration/dirtyrate.c
+++ b/migration/dirtyrate.c
@@ -295,10 +295,38 @@ static void set_dirty_rate_stage(CalculatingDirtyRateStage ratestage)
     calculating_dirty_rate_stage = ratestage;
 }
 
+static int64_t block_sample_gap_period(int64_t msec, int64_t initial_time)
+{
+    int64_t current_time;
+
+    current_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
+    if ((current_time - initial_time) >= msec) {
+        msec = current_time - initial_time;
+    } else {
+        g_usleep((msec + initial_time - current_time) * 1000);
+    }
+
+    return msec;
+}
+
+static int64_t get_sample_gap_period(struct dirtyrate_config config)
+{
+    int64_t msec;
+
+    msec = config.sample_period_seconds * 1000;
+    if (msec <= MIN_FETCH_DIRTYRATE_TIME_MSEC || msec > MAX_FETCH_DIRTYRATE_TIME_MSEC) {
+        msec = DEFAULT_FETCH_DIRTYRATE_TIME_MSEC;
+    }
+    return msec;
+}
+
 void *get_dirtyrate_thread(void *arg)
 {
     struct dirtyrate_config config = *(struct dirtyrate_config *)arg;
     int64_t msec = 0;
+
+    /* max period is 60 seconds */
+    msec = get_sample_gap_period(config);
  
     set_dirty_rate_stage(CAL_DIRTY_RATE_ING);
 
diff --git a/migration/dirtyrate.h b/migration/dirtyrate.h
index 4d9b3b8..5aef2d7 100644
--- a/migration/dirtyrate.h
+++ b/migration/dirtyrate.h
@@ -14,12 +14,16 @@
 #define QEMU_MIGRATION_DIRTYRATE_H
 
 /* take 256 pages per GB for cal dirty rate */
-#define DIRTYRATE_DEFAULT_SAMPLE_PAGES    256
+#define DIRTYRATE_DEFAULT_SAMPLE_PAGES  256
 #define DIRTYRATE_SAMPLE_PAGE_SIZE      4096
 #define DIRTYRATE_PAGE_SIZE_SHIFT       12
 #define BLOCK_INFO_MAX_LEN              256
 #define PAGE_SIZE_SHIFT                 20
 
+#define MIN_FETCH_DIRTYRATE_TIME_MSEC        0
+#define MAX_FETCH_DIRTYRATE_TIME_MSEC        60000
+#define DEFAULT_FETCH_DIRTYRATE_TIME_MSEC    1000
+
 struct dirtyrate_config {
     uint64_t sample_pages_per_gigabytes;
     int64_t sample_period_seconds;
-- 
1.8.3.1