[PATCH v6 08/12] migration/dirtyrate: skip sampling ramblock with size below MIN_RAMBLOCK_SIZE

From: Chuan Zheng <zhengchuan@huawei.com>
To: <quintela@redhat.com>, <eblake@redhat.com>, <dgilbert@redhat.com>,
	<berrange@redhat.com>, <dme@dme.org>
Cc: alex.chen@huawei.com, ann.zhuangyanying@huawei.com,
	zhang.zhanghailiang@huawei.com, xiexiangyou@huawei.com,
	qemu-devel@nongnu.org
Subject: [PATCH v6 08/12] migration/dirtyrate: skip sampling ramblock with size below MIN_RAMBLOCK_SIZE
Date: Sat, 29 Aug 2020 10:52:53 +0800	[thread overview]
Message-ID: <1598669577-76914-9-git-send-email-zhengchuan@huawei.com> (raw)
In-Reply-To: <1598669577-76914-1-git-send-email-zhengchuan@huawei.com>

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

Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
---
 migration/dirtyrate.c | 19 +++++++++++++++++++
 migration/dirtyrate.h |  5 +++++
 2 files changed, 24 insertions(+)

diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
index 9cc2cbb..420fc59 100644
--- a/migration/dirtyrate.c
+++ b/migration/dirtyrate.c
@@ -164,6 +164,19 @@ alloc_ramblock_dirty_info(int *block_index,
     return block_dinfo;
 }
 
+static bool skip_sample_ramblock(RAMBlock *block)
+{
+    /*
+     * Consider ramblock with size larger than 128M is what we
+     * want to sample.
+     */
+    if (qemu_ram_get_used_length(block) < (MIN_RAMBLOCK_SIZE << 10)) {
+        return true;
+    }
+
+    return false;
+}
+
 static int record_ramblock_hash_info(struct RamblockDirtyInfo **block_dinfo,
                                      struct DirtyRateConfig config,
                                      int *block_index)
@@ -174,6 +187,9 @@ static int record_ramblock_hash_info(struct RamblockDirtyInfo **block_dinfo,
     int index = 0;
 
     RAMBLOCK_FOREACH_MIGRATABLE(block) {
+        if (skip_sample_ramblock(block)) {
+            continue;
+        }
         dinfo = alloc_ramblock_dirty_info(&index, dinfo);
         if (dinfo == NULL) {
             return -1;
@@ -241,6 +257,9 @@ static int compare_page_hash_info(struct RamblockDirtyInfo *info,
     RAMBlock *block = NULL;
 
     RAMBLOCK_FOREACH_MIGRATABLE(block) {
+        if (skip_sample_ramblock(block)) {
+            continue;
+        }
         block_dinfo = find_page_matched(block, block_index + 1, info);
         if (block_dinfo == NULL) {
             continue;
diff --git a/migration/dirtyrate.h b/migration/dirtyrate.h
index a3ee305..faaf9da 100644
--- a/migration/dirtyrate.h
+++ b/migration/dirtyrate.h
@@ -24,6 +24,11 @@
  */
 #define RAMBLOCK_INFO_MAX_LEN                     256
 
+/*
+ * Minimum RAMBlock size to sample, in megabytes.
+ */
+#define MIN_RAMBLOCK_SIZE                         128
+
 struct DirtyRateConfig {
     uint64_t sample_pages_per_gigabytes; /* sample pages per GB */
     int64_t sample_period_seconds; /* time duration between two sampling */
-- 
1.8.3.1


