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authorNicholas Piggin <npiggin@gmail.com>2017-06-04 15:06:22 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2017-06-05 09:55:01 +0300
commitb27ce776852078df9e14a223b375db6507096963 (patch)
treeeb984dbaed913df3437a0faec2e32023dc3564d1 /tools/testing/selftests/powerpc/benchmarks
parentb802ab46ba12c617fd55b072f1906627e636947b (diff)
downloadlinux-b27ce776852078df9e14a223b375db6507096963.tar.xz
selftests/powerpc: context_switch use private futexes with threads
This reduces overhead of mutex locking and increases context switch rate significantly (which helps to measure and profile the context switch path). Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'tools/testing/selftests/powerpc/benchmarks')
-rw-r--r--tools/testing/selftests/powerpc/benchmarks/context_switch.c53
1 files changed, 33 insertions, 20 deletions
diff --git a/tools/testing/selftests/powerpc/benchmarks/context_switch.c b/tools/testing/selftests/powerpc/benchmarks/context_switch.c
index 778f5fbfd784..f4241339edd2 100644
--- a/tools/testing/selftests/powerpc/benchmarks/context_switch.c
+++ b/tools/testing/selftests/powerpc/benchmarks/context_switch.c
@@ -258,9 +258,14 @@ static unsigned long xchg(unsigned long *p, unsigned long val)
return __atomic_exchange_n(p, val, __ATOMIC_SEQ_CST);
}
+static int processes;
+
static int mutex_lock(unsigned long *m)
{
int c;
+ int flags = FUTEX_WAIT;
+ if (!processes)
+ flags |= FUTEX_PRIVATE_FLAG;
c = cmpxchg(m, 0, 1);
if (!c)
@@ -270,7 +275,7 @@ static int mutex_lock(unsigned long *m)
c = xchg(m, 2);
while (c) {
- sys_futex(m, FUTEX_WAIT, 2, NULL, NULL, 0);
+ sys_futex(m, flags, 2, NULL, NULL, 0);
c = xchg(m, 2);
}
@@ -279,12 +284,16 @@ static int mutex_lock(unsigned long *m)
static int mutex_unlock(unsigned long *m)
{
+ int flags = FUTEX_WAKE;
+ if (!processes)
+ flags |= FUTEX_PRIVATE_FLAG;
+
if (*m == 2)
*m = 0;
else if (xchg(m, 0) == 1)
return 0;
- sys_futex(m, FUTEX_WAKE, 1, NULL, NULL, 0);
+ sys_futex(m, flags, 1, NULL, NULL, 0);
return 0;
}
@@ -293,26 +302,32 @@ static unsigned long *m1, *m2;
static void futex_setup(int cpu1, int cpu2)
{
- int shmid;
- void *shmaddr;
+ if (!processes) {
+ static unsigned long _m1, _m2;
+ m1 = &_m1;
+ m2 = &_m2;
+ } else {
+ int shmid;
+ void *shmaddr;
- shmid = shmget(IPC_PRIVATE, getpagesize(), SHM_R | SHM_W);
- if (shmid < 0) {
- perror("shmget");
- exit(1);
- }
+ shmid = shmget(IPC_PRIVATE, getpagesize(), SHM_R | SHM_W);
+ if (shmid < 0) {
+ perror("shmget");
+ exit(1);
+ }
- shmaddr = shmat(shmid, NULL, 0);
- if (shmaddr == (char *)-1) {
- perror("shmat");
- shmctl(shmid, IPC_RMID, NULL);
- exit(1);
- }
+ shmaddr = shmat(shmid, NULL, 0);
+ if (shmaddr == (char *)-1) {
+ perror("shmat");
+ shmctl(shmid, IPC_RMID, NULL);
+ exit(1);
+ }
- shmctl(shmid, IPC_RMID, NULL);
+ shmctl(shmid, IPC_RMID, NULL);
- m1 = shmaddr;
- m2 = shmaddr + sizeof(*m1);
+ m1 = shmaddr;
+ m2 = shmaddr + sizeof(*m1);
+ }
*m1 = 0;
*m2 = 0;
@@ -352,8 +367,6 @@ static struct actions futex_actions = {
.thread2 = futex_thread2,
};
-static int processes;
-
static struct option options[] = {
{ "test", required_argument, 0, 't' },
{ "process", no_argument, &processes, 1 },