Re: [Qemu-devel] [PATCH v6 5/5] qemu-iotests: Add 093 for IO throttling

[Fam Zheng <famz@redhat.com>]

On Wed, 01/28 11:22, Max Reitz wrote:
> On 2015-01-27 at 21:28, Fam Zheng wrote:
> >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>
> >---
> >  tests/qemu-iotests/093     | 120 +++++++++++++++++++++++++++++++++++++++++++++
> >  tests/qemu-iotests/093.out |   5 ++
> >  tests/qemu-iotests/group   |   1 +
> >  3 files changed, 126 insertions(+)
> >  create mode 100755 tests/qemu-iotests/093
> >  create mode 100644 tests/qemu-iotests/093.out
> >
> >diff --git a/tests/qemu-iotests/093 b/tests/qemu-iotests/093
> >new file mode 100755
> >index 0000000..2866536
> >--- /dev/null
> >+++ b/tests/qemu-iotests/093
> >@@ -0,0 +1,120 @@
> >+#!/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']) + \
> >+                params['bps_max'] / rq_size / 2 + \
> >+                params['iops_max']
> 
> I guess the divisions by two are because those values represent read and
> write operations combined. Shouldn't iops_max be divided by two, too, then?
> 
> >+        rd_nr *= seconds * 2
> >+        wr_nr = max(params['bps'] / rq_size / 2,
> >+                    params['bps_wr'] / rq_size,
> >+                    params['iops'] / 2,
> >+                    params['iops_wr']) + \
> >+                params['bps_max'] / rq_size / 2 + \
> >+                params['iops_max']
> >+        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))
> 
> Hm, you're not checking bps_max and iops_max here. Should you be?

I never really liked these two parameters, but now that you asked, probably
yes (to this question and above). :)

Fam


> 
> Apart from these two (minor) things: Works for me! :-)
> 
> Max
> 
> >+
> >+    def test_all(self):
> >+        params = {"bps": 4096,
> >+                  "bps_rd": 4096,
> >+                  "bps_wr": 4096,
> >+                  "bps_max": 4096,
> >+                  "iops": 10,
> >+                  "iops_rd": 10,
> >+                  "iops_wr": 10,
> >+                  "iops_max": 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"])
> >diff --git a/tests/qemu-iotests/093.out b/tests/qemu-iotests/093.out
> >new file mode 100644
> >index 0000000..fbc63e6
> >--- /dev/null
> >+++ b/tests/qemu-iotests/093.out
> >@@ -0,0 +1,5 @@
> >+..
> >+----------------------------------------------------------------------
> >+Ran 2 tests
> >+
> >+OK
> >diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
> >index f8bf354..0272c9a 100644
> >--- a/tests/qemu-iotests/group
> >+++ b/tests/qemu-iotests/group
> >@@ -99,6 +99,7 @@
> >  090 rw auto quick
> >  091 rw auto
> >  092 rw auto quick
> >+093 auto
> >  095 rw auto quick
> >  097 rw auto backing
> >  098 rw auto backing quick
>