qemu-iotests: Add 093 for IO throttling

This case utilizes qemu-io command "aio_{read,write} -q" to verify the
effectiveness of IO throttling options.

It's implemented by driving the vm timer from qtest protocol, so the
throttling timers are signaled with determinied time duration. Then we
verify the completed IO requests are within 10% error of bps and iops
limits.

"null" protocol is used as the disk backend so that no actual disk IO is
performed on host, this will make the blockstats much more
deterministic. Both "null-aio" and "null-co" are covered, which is also
a simple cross validation test for the driver code.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 1422586186-9925-6-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

tests/qemu-iotests/093

@@ -0,0 +1,114 @@
+#!/usr/bin/env python
+#
+# Tests for IO throttling
+#
+# Copyright (C) 2015 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import iotests
+
+class ThrottleTestCase(iotests.QMPTestCase):
+    test_img = "null-aio://"
+
+    def blockstats(self, device):
+        result = self.vm.qmp("query-blockstats")
+        for r in result['return']:
+            if r['device'] == device:
+                stat = r['stats']
+                return stat['rd_bytes'], stat['rd_operations'], stat['wr_bytes'], stat['wr_operations']
+        raise Exception("Device not found for blockstats: %s" % device)
+
+    def setUp(self):
+        self.vm = iotests.VM().add_drive(self.test_img)
+        self.vm.launch()
+
+    def tearDown(self):
+        self.vm.shutdown()
+
+    def do_test_throttle(self, seconds, params):
+        def check_limit(limit, num):
+            # IO throttling algorithm is discrete, allow 10% error so the test
+            # is more robust
+            return limit == 0 or \
+                   (num < seconds * limit * 1.1
+                   and num > seconds * limit * 0.9)
+
+        nsec_per_sec = 1000000000
+
+        params['device'] = 'drive0'
+
+        result = self.vm.qmp("block_set_io_throttle", conv_keys=False, **params)
+        self.assert_qmp(result, 'return', {})
+
+        # Set vm clock to a known value
+        ns = seconds * nsec_per_sec
+        self.vm.qtest("clock_step %d" % ns)
+
+        # Submit enough requests. They will drain bps_max and iops_max, but the
+        # rest requests won't get executed until we advance the virtual clock
+        # with qtest interface
+        rq_size = 512
+        rd_nr = max(params['bps'] / rq_size / 2,
+                    params['bps_rd'] / rq_size,
+                    params['iops'] / 2,
+                    params['iops_rd'])
+        rd_nr *= seconds * 2
+        wr_nr = max(params['bps'] / rq_size / 2,
+                    params['bps_wr'] / rq_size,
+                    params['iops'] / 2,
+                    params['iops_wr'])
+        wr_nr *= seconds * 2
+        for i in range(rd_nr):
+            self.vm.hmp_qemu_io("drive0", "aio_read %d %d" % (i * rq_size, rq_size))
+        for i in range(wr_nr):
+            self.vm.hmp_qemu_io("drive0", "aio_write %d %d" % (i * rq_size, rq_size))
+
+        start_rd_bytes, start_rd_iops, start_wr_bytes, start_wr_iops = self.blockstats('drive0')
+
+        self.vm.qtest("clock_step %d" % ns)
+        end_rd_bytes, end_rd_iops, end_wr_bytes, end_wr_iops = self.blockstats('drive0')
+
+        rd_bytes = end_rd_bytes - start_rd_bytes
+        rd_iops = end_rd_iops - start_rd_iops
+        wr_bytes = end_wr_bytes - start_wr_bytes
+        wr_iops = end_wr_iops - start_wr_iops
+
+        self.assertTrue(check_limit(params['bps'], rd_bytes + wr_bytes))
+        self.assertTrue(check_limit(params['bps_rd'], rd_bytes))
+        self.assertTrue(check_limit(params['bps_wr'], wr_bytes))
+        self.assertTrue(check_limit(params['iops'], rd_iops + wr_iops))
+        self.assertTrue(check_limit(params['iops_rd'], rd_iops))
+        self.assertTrue(check_limit(params['iops_wr'], wr_iops))
+
+    def test_all(self):
+        params = {"bps": 4096,
+                  "bps_rd": 4096,
+                  "bps_wr": 4096,
+                  "iops": 10,
+                  "iops_rd": 10,
+                  "iops_wr": 10,
+                 }
+        # Pick each out of all possible params and test
+        for tk in params:
+            limits = dict([(k, 0) for k in params])
+            limits[tk] = params[tk]
+            self.do_test_throttle(5, limits)
+
+class ThrottleTestCoroutine(ThrottleTestCase):
+    test_img = "null-co://"
+
+if __name__ == '__main__':
+    iotests.main(supported_fmts=["raw"])

tests/qemu-iotests/093.out

@@ -0,0 +1,5 @@
+..
+----------------------------------------------------------------------
+Ran 2 tests
+
+OK

tests/qemu-iotests/group

@@ -99,6 +99,7 @@
 090 rw auto quick
 091 rw auto
 092 rw auto quick
+093 auto
 094 rw auto quick
 095 rw auto quick
 097 rw auto backing