From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

In travis, with gcov and gprof we're seeing timeouts; hopefully fix
this by increasing the test timeouts a bit, but for xbzrle ensure it
really does get a couple of cycles through to test the cache.

I think the problem in travis is we have about 2 host CPU threads,
in the test we have at least 3:
   a) The vCPU thread (100% flat out)
   b) The source migration thread
   c) The destination migration thread

if (b) & (c) are slow for any reason - gcov+gperf or a slow host -
then they're sharing one host CPU thread so limit the migration
bandwidth.

Tested on my laptop with:
   taskset -c 0,1 ./tests/qtest/migration-test -p /x86_64/migration

Reported-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20201008160330.130431-1-dgilbert@redhat.com>
[thuth: Move the #define to the right location]
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 tests/qtest/migration-test.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c
index 00a233cd8c..f410ec5996 100644
--- a/tests/qtest/migration-test.c
+++ b/tests/qtest/migration-test.c
@@ -34,6 +34,9 @@ unsigned start_address;
 unsigned end_address;
 static bool uffd_feature_thread_id;
 
+/* A downtime where the test really should converge */
+#define CONVERGE_DOWNTIME 1000
+
 #if defined(__linux__)
 #include <sys/syscall.h>
 #include <sys/vfs.h>
@@ -864,8 +867,7 @@ static void test_precopy_unix(void)
 
     wait_for_migration_pass(from);
 
-    /* 300 ms should converge */
-    migrate_set_parameter_int(from, "downtime-limit", 300);
+    migrate_set_parameter_int(from, "downtime-limit", CONVERGE_DOWNTIME);
 
     if (!got_stop) {
         qtest_qmp_eventwait(from, "STOP");
@@ -946,10 +948,12 @@ static void test_xbzrle(const char *uri)
 
     migrate_qmp(from, uri, "{}");
 
+    wait_for_migration_pass(from);
+    /* Make sure we have 2 passes, so the xbzrle cache gets a workout */
     wait_for_migration_pass(from);
 
-    /* 300ms should converge */
-    migrate_set_parameter_int(from, "downtime-limit", 300);
+    /* 1000ms should converge */
+    migrate_set_parameter_int(from, "downtime-limit", 1000);
 
     if (!got_stop) {
         qtest_qmp_eventwait(from, "STOP");
@@ -999,8 +1003,7 @@ static void test_precopy_tcp(void)
 
     wait_for_migration_pass(from);
 
-    /* 300ms should converge */
-    migrate_set_parameter_int(from, "downtime-limit", 300);
+    migrate_set_parameter_int(from, "downtime-limit", CONVERGE_DOWNTIME);
 
     if (!got_stop) {
         qtest_qmp_eventwait(from, "STOP");
@@ -1068,8 +1071,7 @@ static void test_migrate_fd_proto(void)
 
     wait_for_migration_pass(from);
 
-    /* 300ms should converge */
-    migrate_set_parameter_int(from, "downtime-limit", 300);
+    migrate_set_parameter_int(from, "downtime-limit", CONVERGE_DOWNTIME);
 
     if (!got_stop) {
         qtest_qmp_eventwait(from, "STOP");
@@ -1304,8 +1306,7 @@ static void test_multifd_tcp(const char *method)
 
     wait_for_migration_pass(from);
 
-    /* 300ms it should converge */
-    migrate_set_parameter_int(from, "downtime-limit", 300);
+    migrate_set_parameter_int(from, "downtime-limit", CONVERGE_DOWNTIME);
 
     if (!got_stop) {
         qtest_qmp_eventwait(from, "STOP");
-- 
2.18.2