[4/4] qemu-iotests: Add 080 for IO throttling

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

The "-a" option will cause qemu-io requests to be accounted.

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 110% of bps and iops limits.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 tests/qemu-iotests/080     | 164 +++++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/080.out |   5 ++
 tests/qemu-iotests/group   |   1 +
 3 files changed, 170 insertions(+)
 create mode 100755 tests/qemu-iotests/080
 create mode 100644 tests/qemu-iotests/080.out

On Wed, Jan 29, 2014 at 04:40:43PM +0800, Fam Zheng wrote:
> This case utilizes qemu-io command "aio_{read,write} -a -q" to verify
> the effectiveness of IO throttling options.
> 
> The "-a" option will cause qemu-io requests to be accounted.
> 
> It's implemented by driving the vm timer from qtest protocol, so the
> throttling timers are signaled with determinied time duration. Then we

s/determinied/determined/

> +class ThrottleTestCase(iotests.QMPTestCase):
> +    image_len = 80 * 1024 * 1024 # MB
> +
> +    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):
> +        qemu_img('create', '-f', iotests.imgfmt, test_img, "1G")
> +        #self.vm = iotests.VM().add_drive(test_img, "bps=1024,bps_max=1")

Commented out line?

> +        self.vm = iotests.VM().add_drive(test_img)
> +        self.vm.launch()
> +
> +    def tearDown(self):
> +        self.vm.shutdown()
> +        os.remove(test_img)
> +
> +    def do_test_throttle(self, seconds=10, **limits):
> +        def check_limit(limit, num):
> +            # IO throttling algorithm is discrete, allow 10% error so the test
> +            # is more deterministic
> +            return limit == 0 or num < seconds * limit * 1.1
> +
> +        nsec_per_sec = 1000000000
> +
> +        limits['bps_max'] = 1
> +        limits['iops_max'] = 1

I *think* this trick is to force throttling not to allow bursts?  Maybe
a comment would be good to clarify.  IIRC when max is 0, burst behavior
is different.

> +        ns += seconds * nsec_per_sec
> +        self.vm.qtest_cmd("clock_step %d" % ns)
> +        # wait for a while to let requests take off
> +        time.sleep(1)

sleep() is evil but I'm not sure there is a better way either... :(

On Wed, Jan 29, 2014 at 04:40:43PM +0800, Fam Zheng wrote:
> +    def do_test_throttle(self, seconds=10, **limits):
> +        def check_limit(limit, num):
> +            # IO throttling algorithm is discrete, allow 10% error so the test
> +            # is more deterministic
> +            return limit == 0 or num < seconds * limit * 1.1
> +
> +        nsec_per_sec = 1000000000
> +
> +        limits['bps_max'] = 1
> +        limits['iops_max'] = 1
> +
> +        # Enqueue many requests to throttling queue
> +        result = self.vm.qmp("block_set_io_throttle", conv_keys=False, **limits)
> +        self.assert_qmp(result, 'return', {})
> +
> +        # Set vm clock to a known value
> +        ns = nsec_per_sec
> +        self.vm.qtest_cmd("clock_step %d" % ns)
> +
> +        # Append many requests into the throttle queue
> +        # They drain bps_max and iops_max
> +        # The rest requests won't get executed until qtest clock is driven
> +        for i in range(1000):
> +            self.vm.hmp_qemu_io("drive0", "aio_read -a -q 0 512")
> +            self.vm.hmp_qemu_io("drive0", "aio_write -a -q 0 512")
> +
> +        start_rd_bytes, start_rd_iops, start_wr_bytes, start_wr_iops = self.blockstats('drive0')
> +
> +        ns += seconds * nsec_per_sec
> +        self.vm.qtest_cmd("clock_step %d" % ns)
> +        # wait for a while to let requests take off
> +        time.sleep(1)
> +        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
> +
> +        assert check_limit(limits['bps'], rd_bytes)
> +        assert check_limit(limits['bps_rd'], rd_bytes)
> +        assert check_limit(limits['bps'], wr_bytes)
> +        assert check_limit(limits['bps_wr'], wr_bytes)
> +        assert check_limit(limits['iops'], rd_iops)
> +        assert check_limit(limits['iops_rd'], rd_iops)
> +        assert check_limit(limits['iops'], wr_iops)
> +        assert check_limit(limits['iops_wr'], wr_iops)
> +
> +    def test_bps(self):
> +        self.do_test_throttle(**{
> +            'device': 'drive0',
> +            'bps': 1000,
> +            'bps_rd': 0,
> +            'bps_wr': 0,
> +            'iops': 0,
> +            'iops_rd': 0,
> +            'iops_wr': 0,
> +            })
> +
> +    def test_bps_rd(self):
> +        self.do_test_throttle(**{
> +            'device': 'drive0',
> +            'bps': 0,
> +            'bps_rd': 1000,
> +            'bps_wr': 0,
> +            'iops': 0,
> +            'iops_rd': 0,
> +            'iops_wr': 0,
> +            })

I guess you'll get more stable behavior with 1024 instead of 1000.  The
request themselves are 512 bytes.

As a side note, I think we'll wait for all 1000 pending requests each
time QEMU shuts down.  Probably not a huge time waste but even 100
requests exceed the I/O limits you've specified.  Perhaps using just 100
will make the test slightly faster.

Le Wednesday 29 Jan 2014 à 16:40:43 (+0800), Fam Zheng a écrit :
> This case utilizes qemu-io command "aio_{read,write} -a -q" to verify
> the effectiveness of IO throttling options.
> 
> The "-a" option will cause qemu-io requests to be accounted.
> 
> 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 110% of bps and iops limits.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  tests/qemu-iotests/080     | 164 +++++++++++++++++++++++++++++++++++++++++++++
>  tests/qemu-iotests/080.out |   5 ++
>  tests/qemu-iotests/group   |   1 +
>  3 files changed, 170 insertions(+)
>  create mode 100755 tests/qemu-iotests/080
>  create mode 100644 tests/qemu-iotests/080.out
> 
> diff --git a/tests/qemu-iotests/080 b/tests/qemu-iotests/080
> new file mode 100755
> index 0000000..222bb37
> --- /dev/null
> +++ b/tests/qemu-iotests/080
> @@ -0,0 +1,164 @@
> +#!/usr/bin/env python
> +#
> +# Tests for IO throttling
> +#
> +# Copyright (C) 2014 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 time
> +import os
> +import iotests
> +from iotests import qemu_img
> +
> +test_img = os.path.join(iotests.test_dir, 'test.img')
> +
> +class ThrottleTestCase(iotests.QMPTestCase):
> +    image_len = 80 * 1024 * 1024 # MB
> +
> +    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):
> +        qemu_img('create', '-f', iotests.imgfmt, test_img, "1G")
> +        #self.vm = iotests.VM().add_drive(test_img, "bps=1024,bps_max=1")
> +        self.vm = iotests.VM().add_drive(test_img)
> +        self.vm.launch()
> +
> +    def tearDown(self):
> +        self.vm.shutdown()
> +        os.remove(test_img)
> +
> +    def do_test_throttle(self, seconds=10, **limits):
> +        def check_limit(limit, num):
> +            # IO throttling algorithm is discrete, allow 10% error so the test
> +            # is more deterministic
> +            return limit == 0 or num < seconds * limit * 1.1
> +
> +        nsec_per_sec = 1000000000
> +
> +        limits['bps_max'] = 1
> +        limits['iops_max'] = 1
> +
> +        # Enqueue many requests to throttling queue
> +        result = self.vm.qmp("block_set_io_throttle", conv_keys=False, **limits)
> +        self.assert_qmp(result, 'return', {})
> +
> +        # Set vm clock to a known value
> +        ns = nsec_per_sec
> +        self.vm.qtest_cmd("clock_step %d" % ns)
> +
> +        # Append many requests into the throttle queue
> +        # They drain bps_max and iops_max
> +        # The rest requests won't get executed until qtest clock is driven
> +        for i in range(1000):
> +            self.vm.hmp_qemu_io("drive0", "aio_read -a -q 0 512")
> +            self.vm.hmp_qemu_io("drive0", "aio_write -a -q 0 512")
> +
> +        start_rd_bytes, start_rd_iops, start_wr_bytes, start_wr_iops = self.blockstats('drive0')
> +
> +        ns += seconds * nsec_per_sec
> +        self.vm.qtest_cmd("clock_step %d" % ns)
> +        # wait for a while to let requests take off
> +        time.sleep(1)
> +        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
> +
> +        assert check_limit(limits['bps'], rd_bytes)
> +        assert check_limit(limits['bps_rd'], rd_bytes)
> +        assert check_limit(limits['bps'], wr_bytes)
> +        assert check_limit(limits['bps_wr'], wr_bytes)
> +        assert check_limit(limits['iops'], rd_iops)
> +        assert check_limit(limits['iops_rd'], rd_iops)
> +        assert check_limit(limits['iops'], wr_iops)
> +        assert check_limit(limits['iops_wr'], wr_iops)
> +
> +    def test_bps(self):
> +        self.do_test_throttle(**{
> +            'device': 'drive0',
> +            'bps': 1000,
> +            'bps_rd': 0,
> +            'bps_wr': 0,
> +            'iops': 0,
> +            'iops_rd': 0,
> +            'iops_wr': 0,
> +            })
> +
> +    def test_bps_rd(self):
> +        self.do_test_throttle(**{
> +            'device': 'drive0',
> +            'bps': 0,
> +            'bps_rd': 1000,
> +            'bps_wr': 0,
> +            'iops': 0,
> +            'iops_rd': 0,
> +            'iops_wr': 0,
> +            })
> +
> +    def test_bps_wr(self):
> +        self.do_test_throttle(**{
> +            'device': 'drive0',
> +            'bps': 0,
> +            'bps_rd': 0,
> +            'bps_wr': 1000,
> +            'iops': 0,
> +            'iops_rd': 0,
> +            'iops_wr': 0,
> +            })
> +
> +    def test_iops(self):
> +        self.do_test_throttle(**{
> +            'device': 'drive0',
> +            'bps': 0,
> +            'bps_rd': 0,
> +            'bps_wr': 0,
> +            'iops': 10,
> +            'iops_rd': 0,
> +            'iops_wr': 0,
> +            })
> +
> +    def test_iops_rd(self):
> +        self.do_test_throttle(**{
> +            'device': 'drive0',
> +            'bps': 0,
> +            'bps_rd': 0,
> +            'bps_wr': 0,
> +            'iops': 0,
> +            'iops_rd': 10,
> +            'iops_wr': 0,
> +            })
> +
> +    def test_iops_wr(self):
> +        self.do_test_throttle(**{
> +            'device': 'drive0',
> +            'bps': 0,
> +            'bps_rd': 0,
> +            'bps_wr': 0,
> +            'iops': 0,
> +            'iops_rd': 0,
> +            'iops_wr': 10,
> +            })
> +
> +if __name__ == '__main__':
> +    iotests.main()
> diff --git a/tests/qemu-iotests/080.out b/tests/qemu-iotests/080.out
> new file mode 100644
> index 0000000..3f8a935
> --- /dev/null
> +++ b/tests/qemu-iotests/080.out
> @@ -0,0 +1,5 @@
> +......
> +----------------------------------------------------------------------
> +Ran 6 tests
> +
> +OK
> diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
> index 03c762f..013a7ef 100644
> --- a/tests/qemu-iotests/group
> +++ b/tests/qemu-iotests/group
> @@ -82,3 +82,4 @@
>  073 rw auto
>  074 rw auto
>  077 rw auto
> +080 rw auto
> -- 
> 1.8.5.3
> 
> 

I like the way it's done.
Reviewed-by: Benoit Canet <benoit@irqsave.net>