[Qemu-devel] [PATCH COLO-Frame v5 23/29] COLO: Do checkpoint according to the result of packets comparation

[zhanghailiang]

Only do checkpoint, when the PVM's and SVM's output net packets are 
inconsistent,
We also limit the min time between two continuous checkpoint action, to
give VM a change to run.

Signed-off-by: zhanghailiang <address@hidden>
Signed-off-by: Li Zhijian <address@hidden>
---
 include/net/colo-nic.h |  2 ++
 migration/colo.c       | 32 ++++++++++++++++++++++++++++++++
 net/colo-nic.c         |  5 +++++
 3 files changed, 39 insertions(+)

diff --git a/include/net/colo-nic.h b/include/net/colo-nic.h
index 809726c..57c6719 100644
--- a/include/net/colo-nic.h
+++ b/include/net/colo-nic.h
@@ -20,4 +20,6 @@ void colo_proxy_destroy(enum colo_mode mode);
 void colo_add_nic_devices(NetClientState *nc);
 void colo_remove_nic_devices(NetClientState *nc);
 
+int colo_proxy_compare(void);
+
 #endif
diff --git a/migration/colo.c b/migration/colo.c
index 22d7df1..a7cead9 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -17,6 +17,13 @@
 #include "migration/migration-failover.h"
 #include "net/colo-nic.h"
 
+/*
+* We should not do checkpoint one after another without any time interval,
+* Because this will lead continuous 'stop' status for VM.
+* CHECKPOINT_MIN_PERIOD is the min time limit between two checkpoint action.
+*/
+#define CHECKPOINT_MIN_PERIOD 100  /* unit: ms */
+
 enum {
     COLO_CHECPOINT_READY = 0x46,
 
@@ -283,6 +290,7 @@ static void *colo_thread(void *opaque)
 {
     MigrationState *s = opaque;
     QEMUFile *colo_control = NULL;
+    int64_t current_time, checkpoint_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
     int ret;
 
     if (colo_proxy_init(COLO_PRIMARY_MODE) != 0) {
@@ -318,15 +326,39 @@ static void *colo_thread(void *opaque)
     trace_colo_vm_state_change("stop", "run");
 
     while (s->state == MIGRATION_STATUS_COLO) {
+        int proxy_checkpoint_req;
+
         if (failover_request_is_set()) {
             error_report("failover request");
             goto out;
         }
+        /* wait for a colo checkpoint */
+        proxy_checkpoint_req = colo_proxy_compare();
+        if (proxy_checkpoint_req < 0) {
+            goto out;
+        } else if (!proxy_checkpoint_req) {
+            /*
+             * No checkpoint is needed, wait for 1ms and then
+             * check if we need checkpoint again
+             */
+            g_usleep(1000);
+            continue;
+        } else {
+            int64_t interval;
+
+            current_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
+            interval = current_time - checkpoint_time;
+            if (interval < CHECKPOINT_MIN_PERIOD) {
+                /* Limit the min time between two checkpoint */
+                g_usleep((1000*(CHECKPOINT_MIN_PERIOD - interval)));
+            }
+        }
 
         /* start a colo checkpoint */
         if (colo_do_checkpoint_transaction(s, colo_control)) {
             goto out;
         }
+        checkpoint_time = qemu_clock_get_ms(QEMU_CLOCK_HOST);
     }
 
 out:
diff --git a/net/colo-nic.c b/net/colo-nic.c
index 9e08fe3..a004e08 100644
--- a/net/colo-nic.c
+++ b/net/colo-nic.c
@@ -390,3 +390,8 @@ void colo_proxy_destroy(enum colo_mode mode)
     nfnl_close(nfnlh);
     teardown_nic(mode, getpid());
 }
+
+int colo_proxy_compare(void)
+{
+    return atomic_xchg(&packet_compare_different, 0);
+}
-- 
1.7.12.4