[PATCH v2 07/10] migration/dirtyrate: skip sampling ramblock with size below MIN_RAMBLOCK_SIZE

[Chuan Zheng <zhengchuan@huawei.com>]

From: Zheng Chuan <zhengchuan@huawei.com>

In order to sample real RAM, skip ramblock with size below
MIN_RAMBLOCK_SIZE which is 128M as default.

Signed-off-by: Zheng Chuan <zhengchuan@huawei.com>
---
 migration/dirtyrate.c | 24 ++++++++++++++++++++++++
 migration/dirtyrate.h |  5 +++++
 2 files changed, 29 insertions(+)

diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
index f136067..3dc9feb 100644
--- a/migration/dirtyrate.c
+++ b/migration/dirtyrate.c
@@ -179,6 +179,24 @@ alloc_ramblock_dirty_info(int *block_index,
     return block_dinfo;
 }
 
+static int skip_sample_ramblock(RAMBlock *block)
+{
+    int64_t ramblock_size;
+
+    /* ramblock size in MB */
+    ramblock_size = qemu_ram_get_used_length(block) >> 20;
+
+    /*
+     * Consider ramblock with size larger than 128M is what we
+     * want to sample.
+     */
+    if (ramblock_size < MIN_RAMBLOCK_SIZE) {
+        return -1;
+    }
+
+    return 0;
+}
+
 static int record_ramblock_hash_info(struct DirtyRateConfig config,
                                      struct RamblockDirtyInfo **block_dinfo, int *block_index)
 {
@@ -188,6 +206,9 @@ static int record_ramblock_hash_info(struct DirtyRateConfig config,
     int index = 0;
 
     RAMBLOCK_FOREACH_MIGRATABLE(block) {
+        if (skip_sample_ramblock(block) < 0) {
+            continue;
+        }
         dinfo = alloc_ramblock_dirty_info(&index, dinfo);
         if (dinfo == NULL)
             return -1;
@@ -263,6 +284,9 @@ static int compare_page_hash_info(struct RamblockDirtyInfo *info, int block_inde
     RAMBlock *block = NULL;
 
     RAMBLOCK_FOREACH_MIGRATABLE(block) {
+        if (skip_sample_ramblock(block) < 0) {
+            continue;
+        }
         block_dinfo = NULL;
         if (!find_page_matched(block, info, block_index + 1, &block_dinfo)) {
             continue;
diff --git a/migration/dirtyrate.h b/migration/dirtyrate.h
index 0812b16..fce2e3b 100644
--- a/migration/dirtyrate.h
+++ b/migration/dirtyrate.h
@@ -31,6 +31,11 @@
 
 #define QCRYPTO_HASH_LEN                          16
 
+/*
+ * minimum ramblock size to sampled
+ */
+#define MIN_RAMBLOCK_SIZE                        128
+
 /* Take 1s as default for calculation duration */
 #define DEFAULT_FETCH_DIRTYRATE_TIME_SEC          1
 
-- 
1.8.3.1