From mboxrd@z Thu Jan 1 00:00:00 1970 From: shuah Subject: Re: [PATCH for 5.1 3/3] rseq/selftests: Adapt number of threads to the number of detected cpus Date: Fri, 19 Apr 2019 08:17:48 -0600 Message-ID: <6ba0796c-8a96-f797-265c-37bfb9b4bb71@kernel.org> References: <20190305194755.2602-1-mathieu.desnoyers@efficios.com> <20190305194755.2602-4-mathieu.desnoyers@efficios.com> <20190419103847.GA111210@gmail.com> <1444419838.71.1555677682502.JavaMail.zimbra@efficios.com> <1266612341.87.1555678507226.JavaMail.zimbra@efficios.com> <614774674.134.1555681346941.JavaMail.zimbra@efficios.com> <1863599735.141.1555681723685.JavaMail.zimbra@efficios.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1863599735.141.1555681723685.JavaMail.zimbra@efficios.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Mathieu Desnoyers , Ingo Molnar Cc: Thomas Gleixner , linux-kernel , linux-api , Peter Zijlstra , "Paul E . McKenney" , Boqun Feng , Andy Lutomirski , Dave Watson , Paul Turner , Andrew Morton , Russell King , Ingo Molnar , "H. Peter Anvin" , Andi Kleen , Chris Lameter , Ben Maurer , rostedt , Josh Triplett , Linus Torvalds , Catalin Marinas , Will List-Id: linux-api@vger.kernel.org On 4/19/19 7:48 AM, Mathieu Desnoyers wrote: > ----- On Apr 19, 2019, at 9:42 AM, Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote: > >> ----- On Apr 19, 2019, at 8:55 AM, Mathieu Desnoyers >> mathieu.desnoyers@efficios.com wrote: >> >>> ----- On Apr 19, 2019, at 8:41 AM, Mathieu Desnoyers >>> mathieu.desnoyers@efficios.com wrote: >>> >>>> ----- On Apr 19, 2019, at 6:38 AM, Ingo Molnar mingo@kernel.org wrote: >>>> >>>>> * Mathieu Desnoyers 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 >>>>>> Cc: Shuah Khan >>>>>> Cc: Thomas Gleixner >>>>>> Cc: Joel Fernandes >>>>>> Cc: Peter Zijlstra >>>>>> Cc: Catalin Marinas >>>>>> Cc: Dave Watson >>>>>> Cc: Will Deacon >>>>>> Cc: Andi Kleen >>>>>> Cc: linux-kselftest@vger.kernel.org >>>>>> Cc: "H . Peter Anvin" >>>>>> Cc: Chris Lameter >>>>>> Cc: Russell King >>>>>> Cc: Michael Kerrisk >>>>>> Cc: "Paul E . McKenney" >>>>>> Cc: Paul Turner >>>>>> Cc: Boqun Feng >>>>>> Cc: Josh Triplett >>>>>> Cc: Steven Rostedt >>>>>> Cc: Ben Maurer >>>>>> Cc: Andy Lutomirski >>>>>> Cc: Andrew Morton >>>>>> Cc: Linus Torvalds >>>>>> --- >>>>>> 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. >>> >>> It looks like gcc-8 optimize away the target of asm goto labels when >>> there are more than one of them on x86-64. I'll try to come up with >>> a simpler reproducer. >> >> It appears to be related to gcc-8 mishandling combination of >> asm goto and thread-local storage input operands on x86-64. >> Here is a simple reproducer: >> >> __thread int var; >> >> static int fct(void) >> { >> asm goto ( "jmp %l[testlabel]\n\t" >> : : [var] "m" (var) : : testlabel); >> return 0; >> testlabel: > > FWIW, if I add an empty > > asm volatile (""); > > here after the label, gcc-8 -O2 builds "something" which is > a bogus assembler (an endless loop) : > > main: > .LFB24: > .cfi_startproc > .L2: > subq $8, %rsp > .cfi_def_cfa_offset 16 > #APP > # 6 "test-asm-goto.c" 1 > jmp .L2 > > # 0 "" 2 > #NO_APP > movl %fs:var@tpoff, %edx > leaq .LC0(%rip), %rsi > movl $1, %edi > xorl %eax, %eax > call __printf_chk@PLT > xorl %eax, %eax > addq $8, %rsp > .cfi_def_cfa_offset 8 > ret > .cfi_endproc > > Thoughts ? > Didn't see problems when I tested it before applying it to linux-kselftest next. I have gcc version 7.3.0 (Ubuntu 7.3.0-27ubuntu1~18.04) thanks, -- Shuah