Re: [Qemu-devel] [PATCH v3 5/6] tests: Add migration xbzrle test

[Juan Quintela <quintela@redhat.com>]

"Dr. David Alan Gilbert" <dgilbert@redhat.com> wrote:
> * Juan Quintela (quintela@redhat.com) wrote:
>> Signed-off-by: Juan Quintela <quintela@redhat.com>
>> ---
>>  tests/migration-test.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 68 insertions(+)
>> 
>> diff --git a/tests/migration-test.c b/tests/migration-test.c
>> index 841c89e28a..41dee78a9a 100644
>> --- a/tests/migration-test.c
>> +++ b/tests/migration-test.c
>> @@ -410,6 +410,20 @@ static void deprecated_set_speed(QTestState *who, const char *value)
>>      migrate_check_parameter(who, "max-bandwidth", value);
>>  }
>>  
>> +static void deprecated_set_cache_size(QTestState *who, const char *value)
>> +{
>> +    QDict *rsp;
>> +    gchar *cmd;
>> +
>> +    cmd = g_strdup_printf("{ 'execute': 'migrate-set-cache-size',"
>> +                          "'arguments': { 'value': %s } }", value);
>> +    rsp = qtest_qmp(who, cmd);
>> +    g_free(cmd);
>> +    g_assert(qdict_haskey(rsp, "return"));
>> +    QDECREF(rsp);
>> +    migrate_check_parameter(who, "xbzrle-cache-size", value);
>> +}
>> +
>>  static void migrate_set_parameter(QTestState *who, const char *parameter,
>>                                    const char *value)
>>  {
>> @@ -424,6 +438,10 @@ static void migrate_set_parameter(QTestState *who, const char *parameter,
>>          deprecated_set_speed(who, "12345");
>>      }
>>  
>> +    if (strcmp(parameter, "xbzrle-cache-size") == 0) {
>> +        deprecated_set_cache_size(who, "4096");
>> +    }
>> +
>>      cmd = g_strdup_printf("{ 'execute': 'migrate-set-parameters',"
>>                            "'arguments': { '%s': %s } }",
>>                            parameter, value);
>> @@ -673,6 +691,55 @@ static void test_precopy_tcp(void)
>>      g_free(port);
>>  }
>>  
>> +static void test_xbzrle(const char *uri)
>> +{
>> +    QTestState *from, *to;
>> +
>> +    test_migrate_start(&from, &to, uri);
>> +
>> +    /* We want to pick a speed slow enough that the test completes
>> +     * quickly, but that it doesn't complete precopy even on a slow
>> +     * machine, so also set the downtime.
>> +     */
>> +    /* 100 ms */
>> +    migrate_set_parameter(from, "downtime-limit", "1");
>
> ? That's 1 ms not 100ms as the comment says?

You are right, fixed all the comments and forget this one.
Fixed.

>> +    /* 1MB/s slow*/
>> +    migrate_set_parameter(from, "max-bandwidth", "1000000000");
>
> That's still 1GB/s isn't it?
> Don't you need to reduce that if xbzrle is actually working otherwise
> it'll complete?

I was doing it differently before:

300ms downtime
1MB/s

But this was not reliable to make me wait for it.

So, I changed it to be:

1GB/s (always full speed)
1ms downtime  (so it never converge)

and I change the downtime to something higher later.


>
>> +    migrate_set_parameter(from, "xbzrle-cache-size", "33554432");
>
> That's 32M - why?

It is a value smaller than the full amount of memory.  I want to test
the xbzrle cache size command.  I don't care about *which* value we are
using, really.

> The test continually rewrites 100M of data; only changing one byte/page
> - so actually the fun way to do the xbzrle test is to leave this as 32M
> here.....

>> +    migrate_set_capability(from, "xbzrle", "true");
>> +    migrate_set_capability(to, "xbzrle", "true");
>> +    /* Wait for the first serial output from the source */
>> +    wait_for_serial("src_serial");
>> +
>> +    migrate(from, uri);
>> +
>> +    wait_for_migration_pass(from);
>> +
>> +    /* 300ms it should converge */
>> +    migrate_set_parameter(from, "downtime-limit", "300");
>
> but first increase the xvzrle cache to 120M and give it a couple of
> seconds delay; you might even find it completes without the downtime
> limit schange; but you should still do that after a few seconds.
> You can check the stats as well, you should get some xbzrle cache hits
> as long as you raised the cache size.

ok, will think something more about this.

Thanks, Juan.


> Dave
>
>> +    if (!got_stop) {
>> +        qtest_qmp_eventwait(from, "STOP");
>> +    }
>> +    qtest_qmp_eventwait(to, "RESUME");
>> +
>> +    wait_for_serial("dest_serial");
>> +    wait_for_migration_complete(from);
>> +
>> +    test_migrate_end(from, to);
>> +}
>> +
>> +static void test_xbzrle_unix(void)
>> +{
>> +    char *uri = g_strdup_printf("unix:%s/migsocket", tmpfs);
>> +
>> +    test_xbzrle(uri);
>> +    g_free(uri);
>> +}
>> +
>> +
>>  int main(int argc, char **argv)
>>  {
>>      char template[] = "/tmp/migration-test-XXXXXX";
>> @@ -695,6 +762,7 @@ int main(int argc, char **argv)
>>      qtest_add_func("/migration/precopy/unix", test_precopy_unix);
>>      qtest_add_func("/migration/precopy/tcp", test_precopy_tcp);
>>      qtest_add_func("/migration/postcopy/unix", test_postcopy);
>> +    qtest_add_func("/migration/xbzrle/unix", test_xbzrle_unix);
>>  
>>      ret = g_test_run();
>>  
>> -- 
>> 2.14.3
>> 
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK