Re: [Qemu-devel] [PATCH v5 5/5] qemu-iotests: Add 093 for IO throttling

[Max Reitz]

On 2015-01-16 at 03:46, 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 <address@hidden>
> ---
>   tests/qemu-iotests/093     | 103 +++++++++++++++++++++++++++++++++++++++++++++
>   tests/qemu-iotests/093.out |   5 +++
>   tests/qemu-iotests/group   |   1 +
>   3 files changed, 109 insertions(+)
>   create mode 100755 tests/qemu-iotests/093
>   create mode 100644 tests/qemu-iotests/093.out

NACK. This literally kills my laptop (I can recover when running this 
test in tmpfs (for some reason inexplicable to me, since this uses the 
null block drivers...), but I cannot when running it on my HDD).

Would it be possible to use larger requests and smaller iops? (Or just 
the same request size but smaller bps as well)

PS: Feel free to tell me I'm doing something wrong, of course. But just 
./check -T -raw -c writethrough 093 just killed my laptop, and simply 
./check -raw 093 would have probably killed it, too, if I wouldn't have 
held down ^C after some seconds (I'm listening to music and that's when 
it began stuttering...).

> diff --git a/tests/qemu-iotests/093 b/tests/qemu-iotests/093
> new file mode 100755
> index 0000000..d12cc25
> --- /dev/null
> +++ b/tests/qemu-iotests/093
> @@ -0,0 +1,103 @@
> +#!/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

"more robust"?

Max