migration: Finer grained tracepoints for POSTCOPY_LISTEN

The enablement of postcopy listening has a few steps, add a few tracepoints to
be there ready for some basic measurements for them.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20220301083925.33483-3-peterx@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/migration/savevm.c b/migration/savevm.c
index 7bb65e1d61..190cc5fc42 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1948,9 +1948,10 @@ static void *postcopy_ram_listen_thread(void *opaque)
 static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
 {
     PostcopyState ps = postcopy_state_set(POSTCOPY_INCOMING_LISTENING);
-    trace_loadvm_postcopy_handle_listen();
     Error *local_err = NULL;
 
+    trace_loadvm_postcopy_handle_listen("enter");
+
     if (ps != POSTCOPY_INCOMING_ADVISE && ps != POSTCOPY_INCOMING_DISCARD) {
         error_report("CMD_POSTCOPY_LISTEN in wrong postcopy state (%d)", ps);
         return -1;
@@ -1965,6 +1966,8 @@ static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
         }
     }
 
+    trace_loadvm_postcopy_handle_listen("after discard");
+
     /*
      * Sensitise RAM - can now generate requests for blocks that don't exist
      * However, at this point the CPU shouldn't be running, and the IO
@@ -1977,6 +1980,8 @@ static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
         }
     }
 
+    trace_loadvm_postcopy_handle_listen("after uffd");
+
     if (postcopy_notify(POSTCOPY_NOTIFY_INBOUND_LISTEN, &local_err)) {
         error_report_err(local_err);
         return -1;
@@ -1991,6 +1996,8 @@ static int loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
     qemu_sem_wait(&mis->listen_thread_sem);
     qemu_sem_destroy(&mis->listen_thread_sem);
 
+    trace_loadvm_postcopy_handle_listen("return");
+
     return 0;
 }