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From: | Max Reitz |
Subject: | Re: [Qemu-devel] [PATCH v5 5/5] qemu-iotests: Add 093 for IO throttling |
Date: | Tue, 27 Jan 2015 11:14:40 -0500 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 |
On 2015-01-26 at 22:03, Fam Zheng wrote:
On Mon, 01/26 15:45, Max Reitz wrote: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.outNACK. 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)Is it because of CPU or memory? 1000 requests for both read and write seem to be overkilling since we are measuring 1000 bps and 10 iops, please try if reducing to 100 requests works for you.
Probably memory, since I seem to recall you having the same model as me, but I can imagine you having more RAM...
100 requests do not work with 128,000 bps/64 iops/10 seconds (because that'd be more than 1 MB of data, whereas 100 requests of 4 kB are of course only 400 kB), but the following constellations work:
- 100 requests/128,000 bps/64 iops/1 second- 100 requests/26,214 bps/8 iops/10 seconds (26,214 is about one tenth of 262,144 which is a multiple of 4,096, so the real value will not be too far off; the iops are limited by $number_of_requests / $duration_in_seconds)
I just hope there won't be some other poor guy for whom even this is too much...
Max
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"?Yes :) Fam
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