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

[Fam Zheng]

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.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)

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.

> 
> 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