----- 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 mathieu.desnoyers@efficios.com 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@efficios.com Cc: Shuah Khan shuah@kernel.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Joel Fernandes joelaf@google.com Cc: Peter Zijlstra peterz@infradead.org Cc: Catalin Marinas catalin.marinas@arm.com Cc: Dave Watson davejwatson@fb.com Cc: Will Deacon will.deacon@arm.com Cc: Andi Kleen andi@firstfloor.org Cc: linux-kselftest@vger.kernel.org Cc: "H . Peter Anvin" hpa@zytor.com Cc: Chris Lameter cl@linux.com Cc: Russell King linux@arm.linux.org.uk Cc: Michael Kerrisk mtk.manpages@gmail.com Cc: "Paul E . McKenney" paulmck@linux.vnet.ibm.com Cc: Paul Turner pjt@google.com Cc: Boqun Feng boqun.feng@gmail.com Cc: Josh Triplett josh@joshtriplett.org Cc: Steven Rostedt rostedt@goodmis.org Cc: Ben Maurer bmaurer@fb.com Cc: Andy Lutomirski luto@amacapital.net Cc: Andrew Morton akpm@linux-foundation.org Cc: Linus Torvalds torvalds@linux-foundation.org
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 ?
Thanks,
Mathieu
return 1;}
int main() { return fct(); }
building with gcc-7 -O2 is fine. Building with gcc-8 -O0 is fine too. Building with gcc-8 -O1 and -O2 fails with:
/tmp/ccuXTFfs.o: In function `main': test-asm-goto.c:(.text.startup+0x1): undefined reference to `.L2' collect2: error: ld returned 1 exit status
With gcc-7 -O2, the assembly of main has the .L2 label:
main: .LFB1: .cfi_startproc #APP # 5 "test-asm-goto.c" 1 jmp .L2
# 0 "" 2 #NO_APP .L4: .L3: xorl %eax, %eax ret .L2: movl $1, %eax ret .cfi_endproc
However, with gcc-8 -O2, it's missing:
main: .LFB1: .cfi_startproc .L3: #APP # 5 "test-asm-goto.c" 1 jmp .L2
# 0 "" 2 #NO_APP xorl %eax, %eax ret .cfi_endproc
It looks like we have a compiler issue. :-/
Thanks,
Mathieu
-- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com