[PATCH for 5.1 3/3] rseq/selftests: Adapt number of threads to the number of detected cpus
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} ${@} ${EXTRA_ARGS} || exit 1 let "i++" done }
* Mathieu Desnoyers mathieu.desnoyers@efficios.com wrote:
On smaller systems, running a test with 200 threads can take a long time on machines with smaller number of CPUs.
Detect the number of online cpus at test runtime, and multiply that by 6 to have 6 rseq threads per cpu preempting each other.
Signed-off-by: Mathieu Desnoyers mathieu.desnoyers@efficios.com Cc: Shuah Khan shuah@kernel.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Joel Fernandes joelaf@google.com Cc: Peter Zijlstra peterz@infradead.org Cc: Catalin Marinas catalin.marinas@arm.com Cc: Dave Watson davejwatson@fb.com Cc: Will Deacon will.deacon@arm.com Cc: Andi Kleen andi@firstfloor.org Cc: linux-kselftest@vger.kernel.org Cc: "H . Peter Anvin" hpa@zytor.com Cc: Chris Lameter cl@linux.com Cc: Russell King linux@arm.linux.org.uk Cc: Michael Kerrisk mtk.manpages@gmail.com Cc: "Paul E . McKenney" paulmck@linux.vnet.ibm.com Cc: Paul Turner pjt@google.com Cc: Boqun Feng boqun.feng@gmail.com Cc: Josh Triplett josh@joshtriplett.org Cc: Steven Rostedt rostedt@goodmis.org Cc: Ben Maurer bmaurer@fb.com Cc: Andy Lutomirski luto@amacapital.net Cc: Andrew Morton akpm@linux-foundation.org Cc: Linus Torvalds torvalds@linux-foundation.org
tools/testing/selftests/rseq/run_param_test.sh | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/rseq/run_param_test.sh b/tools/testing/selftests/rseq/run_param_test.sh index 3acd6d75ff9f..e426304fd4a0 100755 --- a/tools/testing/selftests/rseq/run_param_test.sh +++ b/tools/testing/selftests/rseq/run_param_test.sh @@ -1,6 +1,8 @@ #!/bin/bash # SPDX-License-Identifier: GPL-2.0+ or MIT +NR_CPUS=`grep '^processor' /proc/cpuinfo | wc -l`
EXTRA_ARGS=${@} 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
./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}
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).
Thanks,
Ingo
----- 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.
Mathieu
Thanks,
Ingo
----- 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.
Thanks,
Mathieu
----- 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: 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
----- 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
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 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 ?
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
----- On Apr 19, 2019, at 10:17 AM, shuah shuah@kernel.org wrote:
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 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 ?
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)
It really appears to be an optimization bug in gcc-8. Considering that bogus compilers are released in the wild, we can hardly justify using the compiler feature that triggers the bogus behavior, even if it gets fixed in the future.
I've prepared a patch that changes the way the __rseq_abi fields are passed to the inline asm. I pass the address of the __rseq_abi TLS as a register input operand rather than each individual field as "m" operand.
I will submit it in a separate thread.
By the way, it affects both x86-32 (building with gcc-8 -m32) and x86-64.
Thanks,
Mathieu
On 4/19/19 8:40 AM, Mathieu Desnoyers wrote:
----- On Apr 19, 2019, at 10:17 AM, shuah shuah@kernel.org wrote:
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 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 ?
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)
It really appears to be an optimization bug in gcc-8. Considering that bogus compilers are released in the wild, we can hardly justify using the compiler feature that triggers the bogus behavior, even if it gets fixed in the future.
I've prepared a patch that changes the way the __rseq_abi fields are passed to the inline asm. I pass the address of the __rseq_abi TLS as a register input operand rather than each individual field as "m" operand.
I will submit it in a separate thread.
By the way, it affects both x86-32 (building with gcc-8 -m32) and x86-64.
Should I drop this patch that is currently in linux-kseltest next? Just confirming if your new patch is supposed to be applied on top of this one or not?
thanks, -- Shuah
----- On Apr 19, 2019, at 2:57 PM, shuah shuah@kernel.org wrote: [...]
Should I drop this patch that is currently in linux-kseltest next? Just confirming if your new patch is supposed to be applied on top of this one or not?
We should keep this patch in linux-kselftest next. The fix applies on top of it.
Thanks,
Mathieu
On 4/19/19 2:59 PM, Mathieu Desnoyers wrote:
----- On Apr 19, 2019, at 2:57 PM, shuah shuah@kernel.org wrote: [...]
Should I drop this patch that is currently in linux-kseltest next? Just confirming if your new patch is supposed to be applied on top of this one or not?
We should keep this patch in linux-kselftest next. The fix applies on top of it.
Will do. Thanks for a quick response.
-- Shuah
linux-kselftest-mirror@lists.linaro.org
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Ingo Molnar -
Mathieu Desnoyers -
shuah