diff options
| -rw-r--r-- | tests/qtest/migration-test.c | 143 |
1 files changed, 125 insertions, 18 deletions
diff --git a/tests/qtest/migration-test.c b/tests/qtest/migration-test.c index b9cc194..efa8c72 100644 --- a/tests/qtest/migration-test.c +++ b/tests/qtest/migration-test.c @@ -47,6 +47,20 @@ static bool got_src_stop; static bool got_dst_resume; /* + * An initial 3 MB offset is used as that corresponds + * to ~1 sec of data transfer with our bandwidth setting. + */ +#define MAGIC_OFFSET_BASE (3 * 1024 * 1024) +/* + * A further 1k is added to ensure we're not a multiple + * of TEST_MEM_PAGE_SIZE, thus avoid clash with writes + * from the migration guest workload. + */ +#define MAGIC_OFFSET_SHUFFLE 1024 +#define MAGIC_OFFSET (MAGIC_OFFSET_BASE + MAGIC_OFFSET_SHUFFLE) +#define MAGIC_MARKER 0xFEED12345678CAFEULL + +/* * Dirtylimit stop working if dirty page rate error * value less than DIRTYLIMIT_TOLERANCE_RANGE */ @@ -445,6 +459,91 @@ static void migrate_ensure_converge(QTestState *who) migrate_set_parameter_int(who, "downtime-limit", 30 * 1000); } +/* + * Our goal is to ensure that we run a single full migration + * iteration, and also dirty memory, ensuring that at least + * one further iteration is required. + * + * We can't directly synchronize with the start of a migration + * so we have to apply some tricks monitoring memory that is + * transferred. + * + * Initially we set the migration bandwidth to an insanely + * low value, with tiny max downtime too. This basically + * guarantees migration will never complete. + * + * This will result in a test that is unacceptably slow though, + * so we can't let the entire migration pass run at this speed. + * Our intent is to let it run just long enough that we can + * prove data prior to the marker has been transferred *AND* + * also prove this transferred data is dirty again. + * + * Before migration starts, we write a 64-bit magic marker + * into a fixed location in the src VM RAM. + * + * Then watch dst memory until the marker appears. This is + * proof that start_address -> MAGIC_OFFSET_BASE has been + * transferred. + * + * Finally we go back to the source and read a byte just + * before the marker untill we see it flip in value. This + * is proof that start_address -> MAGIC_OFFSET_BASE + * is now dirty again. + * + * IOW, we're guaranteed at least a 2nd migration pass + * at this point. + * + * We can now let migration run at full speed to finish + * the test + */ +static void migrate_prepare_for_dirty_mem(QTestState *from) +{ + /* + * The guest workflow iterates from start_address to + * end_address, writing 1 byte every TEST_MEM_PAGE_SIZE + * bytes. + * + * IOW, if we write to mem at a point which is NOT + * a multiple of TEST_MEM_PAGE_SIZE, our write won't + * conflict with the migration workflow. + * + * We put in a marker here, that we'll use to determine + * when the data has been transferred to the dst. + */ + qtest_writeq(from, start_address + MAGIC_OFFSET, MAGIC_MARKER); +} + +static void migrate_wait_for_dirty_mem(QTestState *from, + QTestState *to) +{ + uint64_t watch_address = start_address + MAGIC_OFFSET_BASE; + uint64_t marker_address = start_address + MAGIC_OFFSET; + uint8_t watch_byte; + + /* + * Wait for the MAGIC_MARKER to get transferred, as an + * indicator that a migration pass has made some known + * amount of progress. + */ + do { + usleep(1000 * 10); + } while (qtest_readq(to, marker_address) != MAGIC_MARKER); + + /* + * Now ensure that already transferred bytes are + * dirty again from the guest workload. Note the + * guest byte value will wrap around and by chance + * match the original watch_byte. This is harmless + * as we'll eventually see a different value if we + * keep watching + */ + watch_byte = qtest_readb(from, watch_address); + do { + usleep(1000 * 10); + } while (qtest_readb(from, watch_address) == watch_byte); +} + + static void migrate_pause(QTestState *who) { qtest_qmp_assert_success(who, "{ 'execute': 'migrate-pause' }"); @@ -577,7 +676,10 @@ typedef struct { MIG_TEST_FAIL_DEST_QUIT_ERR, } result; - /* Optional: set number of migration passes to wait for, if live==true */ + /* + * Optional: set number of migration passes to wait for, if live==true. + * If zero, then merely wait for a few MB of dirty data + */ unsigned int iterations; /* @@ -1165,12 +1267,14 @@ static int migrate_postcopy_prepare(QTestState **from_ptr, migrate_ensure_non_converge(from); + migrate_prepare_for_dirty_mem(from); + /* Wait for the first serial output from the source */ wait_for_serial("src_serial"); migrate_qmp(from, uri, "{}"); - wait_for_migration_pass(from); + migrate_wait_for_dirty_mem(from, to); *from_ptr = from; *to_ptr = to; @@ -1405,14 +1509,8 @@ static void test_precopy_common(MigrateCommon *args) } if (args->live) { - /* - * Testing live migration, we want to ensure that some - * memory is re-dirtied after being transferred, so that - * we exercise logic for dirty page handling. We achieve - * this with a ridiculosly low bandwidth that guarantees - * non-convergance. - */ migrate_ensure_non_converge(from); + migrate_prepare_for_dirty_mem(from); } else { /* * Testing non-live migration, we allow it to run at @@ -1447,13 +1545,16 @@ static void test_precopy_common(MigrateCommon *args) } } else { if (args->live) { - if (args->iterations) { - while (args->iterations--) { - wait_for_migration_pass(from); - } - } else { + /* + * For initial iteration(s) we must do a full pass, + * but for the final iteration, we need only wait + * for some dirty mem before switching to converge + */ + while (args->iterations > 1) { wait_for_migration_pass(from); + args->iterations--; } + migrate_wait_for_dirty_mem(from, to); migrate_ensure_converge(from); @@ -1586,6 +1687,9 @@ static void test_ignore_shared(void) return; } + migrate_ensure_non_converge(from); + migrate_prepare_for_dirty_mem(from); + migrate_set_capability(from, "x-ignore-shared", true); migrate_set_capability(to, "x-ignore-shared", true); @@ -1594,7 +1698,7 @@ static void test_ignore_shared(void) migrate_qmp(from, uri, "{}"); - wait_for_migration_pass(from); + migrate_wait_for_dirty_mem(from, to); if (!got_src_stop) { qtest_qmp_eventwait(from, "STOP"); @@ -2325,6 +2429,7 @@ static void test_multifd_tcp_cancel(void) } migrate_ensure_non_converge(from); + migrate_prepare_for_dirty_mem(from); migrate_set_parameter_int(from, "multifd-channels", 16); migrate_set_parameter_int(to, "multifd-channels", 16); @@ -2343,7 +2448,7 @@ static void test_multifd_tcp_cancel(void) migrate_qmp(from, uri, "{}"); - wait_for_migration_pass(from); + migrate_wait_for_dirty_mem(from, to); migrate_cancel(from); @@ -2372,11 +2477,13 @@ static void test_multifd_tcp_cancel(void) wait_for_migration_status(from, "cancelled", NULL); - migrate_ensure_converge(from); + migrate_ensure_non_converge(from); migrate_qmp(from, uri, "{}"); - wait_for_migration_pass(from); + migrate_wait_for_dirty_mem(from, to); + + migrate_ensure_converge(from); if (!got_src_stop) { qtest_qmp_eventwait(from, "STOP"); |