[RFC PATCH 8/8] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function

[Chuan Zheng <zhengchuan@huawei.com>]

From: Zheng Chuan <zhengchuan@huawei.com>

Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function which could be called
by libvirt api.

Signed-off-by: Zheng Chuan <zhengchuan@huawei.com>
Signed-off-by: YanYing Zhang <ann.zhuangyanying@huawei.com>
---
 migration/Makefile.objs |  1 +
 migration/dirtyrate.c   | 45 +++++++++++++++++++++++++++++++++++++++++++++
 qapi/migration.json     | 24 ++++++++++++++++++++++++
 qapi/pragma.json        |  3 ++-
 4 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/migration/Makefile.objs b/migration/Makefile.objs
index 0fc619e..12ae98c 100644
--- a/migration/Makefile.objs
+++ b/migration/Makefile.objs
@@ -6,6 +6,7 @@ common-obj-y += qemu-file.o global_state.o
 common-obj-y += qemu-file-channel.o
 common-obj-y += xbzrle.o postcopy-ram.o
 common-obj-y += qjson.o
+common-obj-y += dirtyrate.o
 common-obj-y += block-dirty-bitmap.o
 common-obj-y += multifd.o
 common-obj-y += multifd-zlib.o
diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
index d87e16d..5717521 100644
--- a/migration/dirtyrate.c
+++ b/migration/dirtyrate.c
@@ -31,6 +31,21 @@ CalculatingDirtyRateStage calculating_dirty_rate_stage = CAL_DIRTY_RATE_INIT;
         INTERNAL_RAMBLOCK_FOREACH(block)                   \
         if (!qemu_ram_is_migratable(block)) {} else
 
+static int64_t get_dirty_rate_info(void)
+{
+    int64_t dirty_rate = dirty_stat.dirty_rate;
+    /*
+     *    Return dirty_rate only when we get CAL_DIRTY_RATE_END.
+     *    And we must initial calculating_dirty_rate_stage.
+     */
+    if (calculating_dirty_rate_stage == CAL_DIRTY_RATE_END) {
+        calculating_dirty_rate_stage = CAL_DIRTY_RATE_INIT;
+        return dirty_rate;
+    }  else {
+        return -1;
+    }
+}
+
 static void reset_dirtyrate_stat(void)
 {
     dirty_stat.total_dirty_samples = 0;
@@ -377,3 +392,33 @@ void *get_dirtyrate_thread(void *arg)
 
     return NULL;
 }
+
+void qmp_cal_dirty_rate(int64_t value, Error **errp)
+{
+    static struct dirtyrate_config dirtyrate_config;
+    QemuThread thread;
+
+    /*
+     * We don't begin calculating thread only when it's in calculating status.
+     */
+    if (calculating_dirty_rate_stage == CAL_DIRTY_RATE_ING) {
+        return;
+    }
+
+    /*
+     * If we get CAL_DIRTY_RATE_END here, libvirtd may be restarted at last round,
+     * we need to initial it.
+     */
+    if (calculating_dirty_rate_stage == CAL_DIRTY_RATE_END)
+        calculating_dirty_rate_stage = CAL_DIRTY_RATE_INIT;
+
+    dirtyrate_config.sample_period_seconds = value;
+    dirtyrate_config.sample_pages_per_gigabytes = sample_pages_per_gigabytes;
+    qemu_thread_create(&thread, "get_dirtyrate", get_dirtyrate_thread,
+                       (void *)&dirtyrate_config, QEMU_THREAD_DETACHED);
+}
+
+int64_t qmp_get_dirty_rate(Error **errp)
+{
+    return get_dirty_rate_info();
+}
diff --git a/qapi/migration.json b/qapi/migration.json
index d500055..59f35bb 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -1621,3 +1621,27 @@
 ##
 { 'event': 'UNPLUG_PRIMARY',
   'data': { 'device-id': 'str' } }
+
+##
+# @cal_dirty_rate:
+#
+# start calculating dirty rate for vm
+#
+# @value: time for sample dirty pages
+#
+# Since: 5.1
+#
+# Example:
+#   {"command": "cal_dirty_rate", "data": {"value": 1} }
+#
+##
+{ 'command': 'cal_dirty_rate', 'data': {'value': 'int64'} }
+
+##
+# @get_dirty_rate:
+#
+# get dirty rate for vm
+#
+# Since: 5.1
+##
+{ 'command': 'get_dirty_rate', 'returns': 'int64' }
diff --git a/qapi/pragma.json b/qapi/pragma.json
index cffae27..ecd294b 100644
--- a/qapi/pragma.json
+++ b/qapi/pragma.json
@@ -10,7 +10,8 @@
         'query-migrate-cache-size',
         'query-tpm-models',
         'query-tpm-types',
-        'ringbuf-read' ],
+        'ringbuf-read',
+        'get_dirty_rate' ],
     'name-case-whitelist': [
         'ACPISlotType',             # DIMM, visible through query-acpi-ospm-status
         'CpuInfoMIPS',              # PC, visible through query-cpu
-- 
1.8.3.1