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Commit 04cf65b7 authored by Harish's avatar Harish Committed by Greg Kroah-Hartman
Browse files

selftests/powerpc: Fix CPU affinity for child process 



[ 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: 00b7ec5c ("selftests/powerpc: Import Anton's context_switch2 benchmark")
Reported-by: default avatarShirisha Ganta <shiganta@in.ibm.com>
Signed-off-by: default avatarSandipan Das <sandipan@linux.ibm.com>
Signed-off-by: default avatarHarish <harish@linux.ibm.com>
Reviewed-by: default avatarKamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Reviewed-by: default avatarSatheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200609081423.529664-1-harish@linux.ibm.com


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 3e95f258

tools/testing/selftests/powerpc/benchmarks/context_switch.c

+16 −5
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#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>
@@ -104,8 +105,9 @@ 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) {
@@ -116,14 +118,23 @@ 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);