Re: [PATCH for 5.1 3/3] rseq/selftests: Adapt number of threads to the number of detected cpus

From: Mathieu Desnoyers
Date: Fri Apr 19 2019 - 14:40:08 EST


----- On Apr 19, 2019, at 6:38 AM, Ingo Molnar mingo@xxxxxxxxxx wrote:

> * Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> wrote:
>
>> On smaller systems, running a test with 200 threads can take a long
>> time on machines with smaller number of CPUs.
>>
>> Detect the number of online cpus at test runtime, and multiply that
>> by 6 to have 6 rseq threads per cpu preempting each other.
>>
>> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
>> Cc: Shuah Khan <shuah@xxxxxxxxxx>
>> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>> Cc: Joel Fernandes <joelaf@xxxxxxxxxx>
>> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
>> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
>> Cc: Dave Watson <davejwatson@xxxxxx>
>> Cc: Will Deacon <will.deacon@xxxxxxx>
>> Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
>> Cc: linux-kselftest@xxxxxxxxxxxxxxx
>> Cc: "H . Peter Anvin" <hpa@xxxxxxxxx>
>> Cc: Chris Lameter <cl@xxxxxxxxx>
>> Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
>> Cc: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
>> Cc: "Paul E . McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
>> Cc: Paul Turner <pjt@xxxxxxxxxx>
>> Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
>> Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
>> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
>> Cc: Ben Maurer <bmaurer@xxxxxx>
>> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
>> ---
>> tools/testing/selftests/rseq/run_param_test.sh | 7 +++++--
>> 1 file changed, 5 insertions(+), 2 deletions(-)
>>
>> diff --git a/tools/testing/selftests/rseq/run_param_test.sh
>> b/tools/testing/selftests/rseq/run_param_test.sh
>> index 3acd6d75ff9f..e426304fd4a0 100755
>> --- a/tools/testing/selftests/rseq/run_param_test.sh
>> +++ b/tools/testing/selftests/rseq/run_param_test.sh
>> @@ -1,6 +1,8 @@
>> #!/bin/bash
>> # SPDX-License-Identifier: GPL-2.0+ or MIT
>>
>> +NR_CPUS=`grep '^processor' /proc/cpuinfo | wc -l`
>> +
>> EXTRA_ARGS=${@}
>>
>> OLDIFS="$IFS"
>> @@ -28,15 +30,16 @@ IFS="$OLDIFS"
>>
>> REPS=1000
>> SLOW_REPS=100
>> +NR_THREADS=$((6*${NR_CPUS}))
>>
>> function do_tests()
>> {
>> local i=0
>> while [ "$i" -lt "${#TEST_LIST[@]}" ]; do
>> echo "Running test ${TEST_NAME[$i]}"
>> - ./param_test ${TEST_LIST[$i]} -r ${REPS} ${@} ${EXTRA_ARGS} || exit 1
>> + ./param_test ${TEST_LIST[$i]} -r ${REPS} -t ${NR_THREADS} ${@} ${EXTRA_ARGS}
>> || exit 1
>> echo "Running compare-twice test ${TEST_NAME[$i]}"
>> - ./param_test_compare_twice ${TEST_LIST[$i]} -r ${REPS} ${@} ${EXTRA_ARGS} ||
>> exit 1
>> + ./param_test_compare_twice ${TEST_LIST[$i]} -r ${REPS} -t ${NR_THREADS} ${@}
>> ${EXTRA_ARGS} || exit 1
>> let "i++"
>> done
>> }
>
> BTW., when trying to build the rseq self-tests I get this build failure:
>
> dagon:~/tip/tools/testing/selftests/rseq> make
> gcc -O2 -Wall -g -I./ -I../../../../usr/include/ -L./ -Wl,-rpath=./ -shared
> -fPIC rseq.c -lpthread -o
> /home/mingo/tip/tools/testing/selftests/rseq/librseq.so
> gcc -O2 -Wall -g -I./ -I../../../../usr/include/ -L./ -Wl,-rpath=./ basic_test.c
> -lpthread -lrseq -o /home/mingo/tip/tools/testing/selftests/rseq/basic_test
> gcc -O2 -Wall -g -I./ -I../../../../usr/include/ -L./ -Wl,-rpath=./
> basic_percpu_ops_test.c -lpthread -lrseq -o
> /home/mingo/tip/tools/testing/selftests/rseq/basic_percpu_ops_test
> /usr/bin/ld: /tmp/ccuHTWnZ.o: in function `rseq_cmpeqv_storev':
> /home/mingo/tip/tools/testing/selftests/rseq/./rseq-x86.h:84: undefined
> reference to `.L8'
> /usr/bin/ld: /home/mingo/tip/tools/testing/selftests/rseq/./rseq-x86.h:84:
> undefined reference to `.L49'
> /usr/bin/ld: /tmp/ccuHTWnZ.o: in function `rseq_cmpnev_storeoffp_load':
> /home/mingo/tip/tools/testing/selftests/rseq/./rseq-x86.h:141: undefined
> reference to `.L57'
> /usr/bin/ld: /tmp/ccuHTWnZ.o:(__rseq_failure+0x8): undefined reference to `.L8'
> /usr/bin/ld: /tmp/ccuHTWnZ.o:(__rseq_failure+0x14): undefined reference to
> `.L49'
> /usr/bin/ld: /tmp/ccuHTWnZ.o:(__rseq_failure+0x20): undefined reference to
> `.L55'
> collect2: error: ld returned 1 exit status
> make: *** [Makefile:22:
> /home/mingo/tip/tools/testing/selftests/rseq/basic_percpu_ops_test] Error 1
>
> Is this a known problem, or do I miss something from my build environment
> perhaps? Vanilla 64-bit Ubuntu 18.10 (Cosmic).

It works fine with gcc-7 (gcc version 7.3.0 (Ubuntu 7.3.0-16ubuntu3))
but indeed I get the same failure with gcc-8 (gcc version 8.0.1 20180414
(experimental) [trunk revision 259383] (Ubuntu 8-20180414-1ubuntu2)).

Thanks for reporting! I will investigate.

Mathieu


>
> Thanks,
>
> Ingo

--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com