On 06/27/2017 02:58 AM, Omar Sandoval wrote: > Hi, James, thanks for sending this in. Sorry for the delay, I've been > out of the office for a couple of weeks. A few comments below. > > On Thu, Jun 08, 2017 at 08:28:12PM +0800, James Wang wrote: >> Add a regression testing for loop device. when an unbound device >> be close that take too long time. kernel will consume serveral orders >> of magnitude more wall time than it does for a mounted device. >> >> Signed-off-by: James Wang <jnwang@xxxxxxxx> >> --- >> tests/loop/002 | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ >> tests/loop/002.out | 2 ++ >> 2 files changed, 79 insertions(+) >> >> diff --git a/tests/loop/002 b/tests/loop/002 >> new file mode 100755 >> index 0000000..fd607d1 >> --- /dev/null >> +++ b/tests/loop/002 >> @@ -0,0 +1,77 @@ >> +#!/bin/bash >> +# >> +# Test if close()ing a unbound loop device is too slow >> +# Copyright (C) 2017 James Wang >> +# >> +# 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 3 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/>. >> + >> +DESCRIPTION="Test if close()ing a unbound loop device is too slow" >> + >> +QUICK=1 >> + >> +function run_test() { > For consistency with everything else in blktests, please don't use > "function" when defining a function. I will fix it. >> + TIMEFORMAT='%5R' >> + time { >> + for f in `ls /dev/loop[0-9]*|sort`; do dd if=$f of=/dev/null bs=512 count=1 >/dev/null 2>&1; done >> + } >> +} >> +function clean_up() { >> + if lsmod | grep loop >/dev/null 2>&1; then >> + umount /dev/loop* >/dev/null 2>&1 >> + losetup -D >> + sleep 5 >> + >> + if ! rmmod loop;then >> + return 2; >> + fi >> + fi >> +} >> + >> +function prepare() { >> + modprobe loop max_loop=64 > If loop is already loaded, this won't work, right? Actually, I could use clean_up() first , but due to My testing machine has a bug causes clean_up() very slow...... I use call clean_up() before prepare(), make sense? > >> + dd if=/dev/zero of=${TMPDIR}/disk bs=512 count=200K >/dev/null 2>&1 >> + for((i=0;i<4;i++)) >> + do >> + losetup -f ${TMPDIR}/disk; >> + done >> + mkfs.ext4 -F /dev/loop0 >/dev/null 2>&1 > Hm, so if I happened to have something I care about on /dev/loop0, > running blktests will destroy it? This is a no-go. Yes, but due to our insert loop module and create a fake-disk and bound to loop0, so format loop0 should doesn't matter. >> + for((i=0;i<4;i++)) >> + do >> + mkdir -p t$i; >> + mount /dev/loop$i t$i; >> + done >> + >> +} >> + >> + >> +test() { >> + echo "Running ${TEST_NAME}" >> + >> + prepare >> + SECONDS=0 >> + run_test >/dev/null 2>&1 >> + DURATION=${SECONDS} > Nifty, I didn't know about $SECONDS. SECONDS is a built-in variable in bash, it will automatic increase. > >> + >> + clean_up >> + if ! clean_up; then >> + echo "Test complete" >> + return 2 >> + fi >> + echo "Test complete" >> + if [[ "${DURATION}" -gt 1 ]]; then >> + return 1 >> + else >> + return 0 >> + fi > I'd really like a meaningful output if this test fails, so something > like this instead of the if/else > > if [[ "${DURATION}" -gt 1 ]]; then > echo "test took too long ($DURATION seconds)" > fi I will fix this. >> +} >> diff --git a/tests/loop/002.out b/tests/loop/002.out >> new file mode 100644 >> index 0000000..5c34a37 >> --- /dev/null >> +++ b/tests/loop/002.out >> @@ -0,0 +1,2 @@ >> +Running loop/002 >> +Test complete >> -- >> 2.12.3 >> > Overall, is there an easier way to test this than setting up 64 loop > devices at modprobe time? E.g., can you losetup -f and run it on a > single loop device many times to measure the same issue? Use many loop devices for get a enough long time to compare with 1 second. if we only create 1 loop device, I afraid it can't be measured. In this scenario, I could get the duration of unbound and bound loop device takes. OK, I could try your suggestion. I will send patch later. James > > Thanks again! > > -- SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
