From: Harish harish@linux.ibm.com
[ Upstream commit 854eb5022be04f81e318765f089f41a57c8e5d83 ]
On systems with large number of cpus, test fails trying to set affinity by calling sched_setaffinity() with smaller size for affinity mask. This patch fixes it by making sure that the size of allocated affinity mask is dependent on the number of CPUs as reported by get_nprocs().
Fixes: 00b7ec5c9cf3 ("selftests/powerpc: Import Anton's context_switch2 benchmark") Reported-by: Shirisha Ganta shiganta@in.ibm.com Signed-off-by: Sandipan Das sandipan@linux.ibm.com Signed-off-by: Harish harish@linux.ibm.com Reviewed-by: Kamalesh Babulal kamalesh@linux.vnet.ibm.com Reviewed-by: Satheesh Rajendran sathnaga@linux.vnet.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20200609081423.529664-1-harish@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- .../powerpc/benchmarks/context_switch.c | 21 ++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-)
diff --git a/tools/testing/selftests/powerpc/benchmarks/context_switch.c b/tools/testing/selftests/powerpc/benchmarks/context_switch.c index f4241339edd2a..7136eae2170b7 100644 --- a/tools/testing/selftests/powerpc/benchmarks/context_switch.c +++ b/tools/testing/selftests/powerpc/benchmarks/context_switch.c @@ -22,6 +22,7 @@ #include <limits.h> #include <sys/time.h> #include <sys/syscall.h> +#include <sys/sysinfo.h> #include <sys/types.h> #include <sys/shm.h> #include <linux/futex.h> @@ -97,8 +98,9 @@ static void start_thread_on(void *(*fn)(void *), void *arg, unsigned long cpu)
static void start_process_on(void *(*fn)(void *), void *arg, unsigned long cpu) { - int pid; - cpu_set_t cpuset; + int pid, ncpus; + cpu_set_t *cpuset; + size_t size;
pid = fork(); if (pid == -1) { @@ -109,14 +111,23 @@ static void start_process_on(void *(*fn)(void *), void *arg, unsigned long cpu) if (pid) return;
- CPU_ZERO(&cpuset); - CPU_SET(cpu, &cpuset); + ncpus = get_nprocs(); + size = CPU_ALLOC_SIZE(ncpus); + cpuset = CPU_ALLOC(ncpus); + if (!cpuset) { + perror("malloc"); + exit(1); + } + CPU_ZERO_S(size, cpuset); + CPU_SET_S(cpu, size, cpuset);
- if (sched_setaffinity(0, sizeof(cpuset), &cpuset)) { + if (sched_setaffinity(0, size, cpuset)) { perror("sched_setaffinity"); + CPU_FREE(cpuset); exit(1); }
+ CPU_FREE(cpuset); fn(arg);
exit(0);