[LTP] [PATCH 0/7] realtime/testpi-4: code cleanup and functional changes on testpi-4

[LTP] [PATCH 0/7] realtime/testpi-4: code cleanup and functional changes on testpi-4

[Gowrishankar]

Following set of patches applies code cleanup and functional changes
in LTP realtime pi-test testpi-4. This test was not patched earlier
when other pi-tests were fixed, with the intension of removing it
from the suite due to similarity with testpi-1. But we decided to
keep this test due to dynamically created global mutex lock.

Order of applying patch is:

[PATCH 1/7] realtime/testpi-4: code cleanup on pi-test 4
[PATCH 2/7] realtime/testpi-4: reuse init_pi_mutex from librttest
[PATCH 3/7] realtime/testpi-4: add test description
[PATCH 4/7] realtime/testpi-4: threads need not set cpu affinity while main does
[PATCH 5/7] realtime/testpi-4: use busy_work_ms from librttest to burn cpu cycles
[PATCH 6/7] realtime/testpi-4: remove thread_stop which is not used anywhere
[PATCH 7/7] realtime/testpi-4: synchronization fixes for high priority noise thread

Thanks,
Gowri


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[LTP] [PATCH 1/7] realtime/testpi-4: code cleanup on pi-test 4

[Gowrishankar]

From: gowrishankar <gowrishankar.m@linux.vnet.ibm.com>

This patch cleans up the testpi-4 so as to follow the
C coding style standards.

Signed-off-by: Gowrishankar <gowrishankar.m@in.ibm.com>
Tested-by: Gowrishankar <gowrishankar.m@in.ibm.com>
Acked-by: Darren Hart <dvhltc@us.ibm.com>
---
 testcases/realtime/func/pi-tests/testpi-4.c |  356 ++++++++++++++-------------
 1 files changed, 186 insertions(+), 170 deletions(-)

diff --git a/testcases/realtime/func/pi-tests/testpi-4.c b/testcases/realtime/func/pi-tests/testpi-4.c
index 1756588..bde3ded 100644
--- a/testcases/realtime/func/pi-tests/testpi-4.c
+++ b/testcases/realtime/func/pi-tests/testpi-4.c
@@ -49,201 +49,217 @@ pthread_barrier_t barrier;
 
 void usage(void)
 {
-        rt_help();
-        printf("testpi-4 specific options:\n");
+	rt_help();
+	printf("testpi-4 specific options:\n");
 }
 
 int parse_args(int c, char *v)
 {
-
-        int handled = 1;
-        switch (c) {
-                case 'h':
-                        usage();
-                        exit(0);
-                default:
-                        handled = 0;
-                        break;
-        }
-        return handled;
+	int handled = 1;
+	switch (c) {
+	case 'h':
+		usage();
+		exit(0);
+	default:
+		handled = 0;
+		break;
+	}
+	return handled;
 }
 
 int gettid(void)
 {
-        return syscall(__NR_gettid);
+	return syscall(__NR_gettid);
 }
 
-typedef void* (*entrypoint_t)(void*);
+typedef void *(*entrypoint_t)(void *);
 
 #define THREAD_STOP    1
 
 pthread_mutex_t *glob_mutex;
 
-void* func_nonrt(void* arg)
+void *func_nonrt(void *arg)
 {
-  struct thread*  pthr = (struct thread* )arg;	
-  int rc, i, j, tid = gettid();
-  cpu_set_t mask;
-  CPU_ZERO(&mask);
-  CPU_SET(0, &mask);
-
-  rc = sched_setaffinity(0, sizeof(mask), &mask);
-  if (rc < 0) {
-     printf("Thread %d: Can't set affinity: %d %s\n", tid, rc, strerror(rc));
-     exit(-1);
-  }
-
-  printf("Thread %d started running with priority %d\n", tid, pthr->priority);
-  pthread_mutex_lock(glob_mutex);
-  printf("Thread %d at start pthread pol %d pri %d - Got global lock\n", tid, pthr->policy, pthr->priority);
-  pthread_barrier_wait(&barrier);
-
-  for (i=0;i<10000;i++) {
-    if (i%100 == 0) {
-      printf("Thread %d loop %d pthread pol %d pri %d\n", tid, i, pthr->policy, pthr->priority);
-      fflush(NULL);
-    }
-    pthr->id++;
-    for (j=0;j<5000;j++) {
-      pthread_mutex_lock(&(pthr->mutex));
-      pthread_mutex_unlock(&(pthr->mutex));
-    }
-  }
-  pthread_mutex_unlock(glob_mutex);
-  return NULL;
+	struct thread *pthr = (struct thread *)arg;
+	int rc, i, j, tid = gettid();
+	cpu_set_t mask;
+	CPU_ZERO(&mask);
+	CPU_SET(0, &mask);
+
+	rc = sched_setaffinity(0, sizeof(mask), &mask);
+	if (rc < 0) {
+		printf("Thread %d: Can't set affinity: %d %s\n",
+			tid, rc, strerror(rc));
+		exit(-1);
+	}
+
+	printf("Thread %d started running with priority %d\n", tid,
+		pthr->priority);
+	pthread_mutex_lock(glob_mutex);
+	printf("Thread %d at start pthread pol %d pri %d - Got global lock\n",
+		tid, pthr->policy, pthr->priority);
+	pthread_barrier_wait(&barrier);
+
+	for (i = 0; i < 10000; i++) {
+		if (i%100 == 0) {
+			printf("Thread %d loop %d pthread pol %d pri %d\n",
+				tid, i, pthr->policy, pthr->priority);
+			fflush(NULL);
+		}
+		pthr->id++;
+		for (j = 0; j < 5000; j++) {
+			pthread_mutex_lock(&(pthr->mutex));
+			pthread_mutex_unlock(&(pthr->mutex));
+		}
+	}
+	pthread_mutex_unlock(glob_mutex);
+	return NULL;
 }
 
-void* func_rt(void* arg)
+void *func_rt(void *arg)
 {
-  struct thread*  pthr = (struct thread* )arg;
-  int rc, i, j, tid = gettid();
-  cpu_set_t mask;
-  CPU_ZERO(&mask);
-  CPU_SET(0, &mask);
-
-  rc = sched_setaffinity(0, sizeof(mask), &mask);
-  if (rc < 0) {
-     printf("Thread %d: Can't set affinity: %d %s\n", tid, rc, strerror(rc));
-     exit(-1);
-  }
-
-  printf("Thread %d started running with prio %d\n", tid, pthr->priority);
-  pthread_barrier_wait(&barrier);
-  pthread_mutex_lock(glob_mutex);
-  printf("Thread %d at start pthread pol %d pri %d - Got global lock\n", tid, pthr->policy, pthr->priority);
-
-  /* we just use the mutex as something to slow things down */
-  /* say who we are and then do nothing for a while.  The aim
-   * of this is to show that high priority threads make more
-   * progress than lower priority threads..
-   */
-  for (i=0;i<1000;i++) {
-    if (i%100 == 0) {
-      printf("Thread %d loop %d pthread pol %d pri %d\n", tid, i, pthr->policy, pthr->priority);
-      fflush(NULL);
-    }
-    pthr->id++;
-    for (j=0;j<5000;j++) {
-      pthread_mutex_lock(&(pthr->mutex));
-      pthread_mutex_unlock(&(pthr->mutex));
-    }
-  }
-  pthread_mutex_unlock(glob_mutex);
-  return NULL;
+	struct thread *pthr = (struct thread *)arg;
+	int rc, i, j, tid = gettid();
+	cpu_set_t mask;
+	CPU_ZERO(&mask);
+	CPU_SET(0, &mask);
+
+	rc = sched_setaffinity(0, sizeof(mask), &mask);
+	if (rc < 0) {
+		printf("Thread %d: Can't set affinity: %d %s\n",
+			tid, rc, strerror(rc));
+		exit(-1);
+	}
+
+	printf("Thread %d started running with prio %d\n", tid,
+		pthr->priority);
+	pthread_barrier_wait(&barrier);
+	pthread_mutex_lock(glob_mutex);
+	printf("Thread %d at start pthread pol %d pri %d - Got global lock\n",
+		tid, pthr->policy, pthr->priority);
+
+	/* we just use the mutex as something to slow things down,
+	 * say who we are and then do nothing for a while.  The aim
+	 * of this is to show that high priority threads make more
+	 * progress than lower priority threads..
+	 */
+	for (i = 0; i < 1000; i++) {
+		if (i%100 == 0) {
+			printf("Thread %d loop %d pthread pol %d pri %d\n",
+				tid, i, pthr->policy, pthr->priority);
+			fflush(NULL);
+		}
+		pthr->id++;
+		for (j = 0; j < 5000; j++) {
+			pthread_mutex_lock(&(pthr->mutex));
+			pthread_mutex_unlock(&(pthr->mutex));
+		}
+	}
+	pthread_mutex_unlock(glob_mutex);
+	return NULL;
 }
 
-void* func_noise(void* arg)
+void *func_noise(void *arg)
 {
-  struct thread*  pthr = (struct thread* )arg;
-  int rc, i, j, tid = gettid();
-  cpu_set_t mask;
-  CPU_ZERO(&mask);
-  CPU_SET(0, &mask);
-
-  rc = sched_setaffinity(0, sizeof(mask), &mask);
-  if (rc < 0) {
-     printf("Thread %d: Can't set affinity: %d %s\n", tid, rc, strerror(rc));
-     exit(-1);
-  }
-
-  printf("Noise Thread started running with prio %d\n", pthr->priority);
-  pthread_barrier_wait(&barrier);
-
-  for (i=0;i<10000;i++) {
-    if (i%100 == 0) {
-      printf("Noise Thread %d loop %d pthread pol %d pri %d\n", tid, i, pthr->policy, pthr->priority);
-      fflush(NULL);
-    }
-    pthr->id++;
-    for (j=0;j<5000;j++) {
-      pthread_mutex_lock(&(pthr->mutex));
-      pthread_mutex_unlock(&(pthr->mutex));
-    }
-  }
-  return NULL;
+	struct thread *pthr = (struct thread *)arg;
+	int rc, i, j, tid = gettid();
+	cpu_set_t mask;
+	CPU_ZERO(&mask);
+	CPU_SET(0, &mask);
+
+	rc = sched_setaffinity(0, sizeof(mask), &mask);
+	if (rc < 0) {
+		printf("Thread %d: Can't set affinity: %d %s\n", tid, rc,
+			strerror(rc));
+		exit(-1);
+	}
+
+	printf("Noise Thread started running with prio %d\n",
+		pthr->priority);
+	pthread_barrier_wait(&barrier);
+
+	for (i = 0; i < 10000; i++) {
+		if (i%100 == 0) {
+			printf("Noise Thread %d loop %d pthread pol %d "\
+				"pri %d\n", tid, i, pthr->policy,
+				pthr->priority);
+			fflush(NULL);
+		}
+		pthr->id++;
+		for (j = 0; j < 5000; j++) {
+			pthread_mutex_lock(&(pthr->mutex));
+			pthread_mutex_unlock(&(pthr->mutex));
+		}
+	}
+	return NULL;
 }
 
 /*
  * Test pthread creation at different thread priorities.
  */
-int main(int argc, char* argv[]) {
-  pthread_mutexattr_t mutexattr;
-  int i, retc, protocol, nopi = 0;
-  cpu_set_t mask;
-  CPU_ZERO(&mask);
-  CPU_SET(0, &mask);
-  setup();
-
-  rt_init("h",parse_args,argc,argv);
-
-  if ((retc = pthread_barrier_init(&barrier, NULL, 5))) {
-    printf("pthread_barrier_init failed: %s\n", strerror(retc));
-    exit(retc);
-  }
-
-  retc = sched_setaffinity(0, sizeof(mask), &mask);
-  if (retc < 0) {
-     printf("Main Thread: Can't set affinity: %d %s\n", retc, strerror(retc));
-     exit(-1);
-  }
-  for (i=0;i<argc;i++) {
-    if (strcmp(argv[i],"nopi") == 0) nopi = 1;
-  }
-
-  printf("Start %s\n", argv[0]);
-
-  glob_mutex = malloc(sizeof(pthread_mutex_t));
-  if (glob_mutex == NULL) {
-     printf("Malloc failed\n");
-     exit(errno);
-  }
-
-  if (!nopi) {
-    if (pthread_mutexattr_init(&mutexattr) != 0) {
-      printf("Failed to init mutexattr\n");
-    }
-    if (pthread_mutexattr_setprotocol(&mutexattr, PTHREAD_PRIO_INHERIT) != 0) {
-      printf("Can't set protocol prio inherit\n");
-    }
-    if (pthread_mutexattr_getprotocol(&mutexattr, &protocol) != 0) {
-      printf("Can't get mutexattr protocol\n");
-    } else {
-      printf("protocol in mutexattr is %d\n", protocol);
-    }
-    if ((retc = pthread_mutex_init(glob_mutex, &mutexattr)) != 0) {
-      printf("Failed to init mutex: %d\n", retc);
-    }
-  }
-
-  create_other_thread(func_nonrt, NULL);
-  create_rr_thread(func_rt, NULL, 20);
-  create_rr_thread(func_rt, NULL, 30);
-  create_rr_thread(func_rt, NULL, 40);
-  create_rr_thread(func_noise, NULL, 40);
-
-  printf("Joining threads\n");
-  join_threads();
-  printf("Done\n");
-
-  return 0;
+int main(int argc, char *argv[])
+{
+	pthread_mutexattr_t mutexattr;
+	int i, retc, protocol, nopi = 0;
+	cpu_set_t mask;
+	CPU_ZERO(&mask);
+	CPU_SET(0, &mask);
+	setup();
+
+	rt_init("h", parse_args, argc, argv);
+
+	retc = pthread_barrier_init(&barrier, NULL, 5);
+	if (retc) {
+		printf("pthread_barrier_init failed: %s\n", strerror(retc));
+		exit(retc);
+	}
+
+	retc = sched_setaffinity(0, sizeof(mask), &mask);
+	if (retc < 0) {
+		printf("Main Thread: Can't set affinity: %d %s\n", retc,
+			strerror(retc));
+		exit(-1);
+	}
+	for (i = 0; i < argc; i++) {
+		if (strcmp(argv[i], "nopi") == 0)
+			nopi = 1;
+	}
+
+	printf("Start %s\n", argv[0]);
+
+	glob_mutex = malloc(sizeof(pthread_mutex_t));
+	if (glob_mutex == NULL) {
+		printf("Malloc failed\n");
+		exit(errno);
+	}
+
+	if (!nopi) {
+		if (pthread_mutexattr_init(&mutexattr) != 0)
+			printf("Failed to init mutexattr\n");
+
+		if (pthread_mutexattr_setprotocol(&mutexattr,
+			 PTHREAD_PRIO_INHERIT) != 0)
+			printf("Can't set protocol prio inherit\n");
+
+		if (pthread_mutexattr_getprotocol(&mutexattr, &protocol) != 0)
+			printf("Can't get mutexattr protocol\n");
+		else
+			printf("protocol in mutexattr is %d\n", protocol);
+
+		retc = pthread_mutex_init(glob_mutex, &mutexattr);
+		if (retc != 0)
+			printf("Failed to init mutex: %d\n", retc);
+	}
+
+	create_other_thread(func_nonrt, NULL);
+	create_rr_thread(func_rt, NULL, 20);
+	create_rr_thread(func_rt, NULL, 30);
+	create_rr_thread(func_rt, NULL, 40);
+	create_rr_thread(func_noise, NULL, 40);
+
+	printf("Joining threads\n");
+	join_threads();
+	printf("Done\n");
+
+	return 0;
 }
-- 
1.7.1


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[LTP] [PATCH 2/7] realtime/testpi-4: reuse init_pi_mutex from librttest

[Gowrishankar]

From: gowrishankar <gowrishankar.m@linux.vnet.ibm.com>

testpi-4 is initializing mutex step by step which can be done
by reusing the init_pi_mutex() funtion available in librttest.

Signed-off-by: Gowrishankar <gowrishankar.m@in.ibm.com>
Tested-by: Gowrishankar <gowrishankar.m@in.ibm.com>
Acked-by: Darren Hart <dvhltc@us.ibm.com>
---
 testcases/realtime/func/pi-tests/testpi-4.c |   22 +++-------------------
 1 files changed, 3 insertions(+), 19 deletions(-)

diff --git a/testcases/realtime/func/pi-tests/testpi-4.c b/testcases/realtime/func/pi-tests/testpi-4.c
index bde3ded..53b47a8 100644
--- a/testcases/realtime/func/pi-tests/testpi-4.c
+++ b/testcases/realtime/func/pi-tests/testpi-4.c
@@ -199,8 +199,7 @@ void *func_noise(void *arg)
  */
 int main(int argc, char *argv[])
 {
-	pthread_mutexattr_t mutexattr;
-	int i, retc, protocol, nopi = 0;
+	int i, retc, nopi = 0;
 	cpu_set_t mask;
 	CPU_ZERO(&mask);
 	CPU_SET(0, &mask);
@@ -233,23 +232,8 @@ int main(int argc, char *argv[])
 		exit(errno);
 	}
 
-	if (!nopi) {
-		if (pthread_mutexattr_init(&mutexattr) != 0)
-			printf("Failed to init mutexattr\n");
-
-		if (pthread_mutexattr_setprotocol(&mutexattr,
-			 PTHREAD_PRIO_INHERIT) != 0)
-			printf("Can't set protocol prio inherit\n");
-
-		if (pthread_mutexattr_getprotocol(&mutexattr, &protocol) != 0)
-			printf("Can't get mutexattr protocol\n");
-		else
-			printf("protocol in mutexattr is %d\n", protocol);
-
-		retc = pthread_mutex_init(glob_mutex, &mutexattr);
-		if (retc != 0)
-			printf("Failed to init mutex: %d\n", retc);
-	}
+	if (!nopi)
+		init_pi_mutex(glob_mutex);
 
 	create_other_thread(func_nonrt, NULL);
 	create_rr_thread(func_rt, NULL, 20);
-- 
1.7.1


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[LTP] [PATCH 3/7] realtime/testpi-4: add test description

[Gowrishankar]

From: gowrishankar <gowrishankar.m@linux.vnet.ibm.com>

This patch adds the description to the test testpi-4.

Signed-off-by: Gowrishankar <gowrishankar.m@in.ibm.com>
Tested-by: Gowrishankar <gowrishankar.m@in.ibm.com>
Acked-by: Darren Hart <dvhltc@us.ibm.com>
---
 testcases/realtime/func/pi-tests/testpi-4.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/testcases/realtime/func/pi-tests/testpi-4.c b/testcases/realtime/func/pi-tests/testpi-4.c
index 53b47a8..6a90771 100644
--- a/testcases/realtime/func/pi-tests/testpi-4.c
+++ b/testcases/realtime/func/pi-tests/testpi-4.c
@@ -20,8 +20,8 @@
  *      testpi-4.c
  *
  * DESCRIPTION
- *
- *
+ *     This testcase verifies that the SCHED_OTHER thread can preempt
+ *     the SCHED_RR thread via priority inheritance.
  *
  * USAGE:
  *      Use run_auto.sh script in current directory to build and run test.
-- 
1.7.1


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[LTP] [PATCH 4/7] realtime/testpi-4: threads need not set cpu affinity while main does

[Gowrishankar]

From: gowrishankar <gowrishankar.m@linux.vnet.ibm.com>

Since main() sets the cpu affinity, it is not necessary for the
spawned threads to do so, as the threads inherit the cpu affinity.

Signed-off-by: Gowrishankar <gowrishankar.m@in.ibm.com>
Tested-by: Gowrishankar <gowrishankar.m@in.ibm.com>
Acked-by: Darren Hart <dvhltc@us.ibm.com>
---
 testcases/realtime/func/pi-tests/testpi-4.c |   36 ++------------------------
 1 files changed, 3 insertions(+), 33 deletions(-)

diff --git a/testcases/realtime/func/pi-tests/testpi-4.c b/testcases/realtime/func/pi-tests/testpi-4.c
index 6a90771..0960c91 100644
--- a/testcases/realtime/func/pi-tests/testpi-4.c
+++ b/testcases/realtime/func/pi-tests/testpi-4.c
@@ -81,17 +81,7 @@ pthread_mutex_t *glob_mutex;
 void *func_nonrt(void *arg)
 {
 	struct thread *pthr = (struct thread *)arg;
-	int rc, i, j, tid = gettid();
-	cpu_set_t mask;
-	CPU_ZERO(&mask);
-	CPU_SET(0, &mask);
-
-	rc = sched_setaffinity(0, sizeof(mask), &mask);
-	if (rc < 0) {
-		printf("Thread %d: Can't set affinity: %d %s\n",
-			tid, rc, strerror(rc));
-		exit(-1);
-	}
+	int i, j, tid = gettid();
 
 	printf("Thread %d started running with priority %d\n", tid,
 		pthr->priority);
@@ -119,17 +109,7 @@ void *func_nonrt(void *arg)
 void *func_rt(void *arg)
 {
 	struct thread *pthr = (struct thread *)arg;
-	int rc, i, j, tid = gettid();
-	cpu_set_t mask;
-	CPU_ZERO(&mask);
-	CPU_SET(0, &mask);
-
-	rc = sched_setaffinity(0, sizeof(mask), &mask);
-	if (rc < 0) {
-		printf("Thread %d: Can't set affinity: %d %s\n",
-			tid, rc, strerror(rc));
-		exit(-1);
-	}
+	int i, j, tid = gettid();
 
 	printf("Thread %d started running with prio %d\n", tid,
 		pthr->priority);
@@ -162,17 +142,7 @@ void *func_rt(void *arg)
 void *func_noise(void *arg)
 {
 	struct thread *pthr = (struct thread *)arg;
-	int rc, i, j, tid = gettid();
-	cpu_set_t mask;
-	CPU_ZERO(&mask);
-	CPU_SET(0, &mask);
-
-	rc = sched_setaffinity(0, sizeof(mask), &mask);
-	if (rc < 0) {
-		printf("Thread %d: Can't set affinity: %d %s\n", tid, rc,
-			strerror(rc));
-		exit(-1);
-	}
+	int i, j, tid = gettid();
 
 	printf("Noise Thread started running with prio %d\n",
 		pthr->priority);
-- 
1.7.1


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[LTP] [PATCH 5/7] realtime/testpi-4: use busy_work_ms from librttest to burn cpu cycles

[Gowrishankar]

From: gowrishankar <gowrishankar.m@linux.vnet.ibm.com>

Instead of lock/unlock of mutex to burn cpu cycles, we can use busy_work_ms
from librttest which is more explicit (burn cycles, not provide some
synchronization).

Also this patch removes the id increment since it is not used.

Signed-off-by: Gowrishankar <gowrishankar.m@in.ibm.com>
Tested-by: Gowrishankar <gowrishankar.m@in.ibm.com>
Acked-by: Darren Hart <dvhltc@us.ibm.com>
---
 testcases/realtime/func/pi-tests/testpi-4.c |   24 ++++++------------------
 1 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/testcases/realtime/func/pi-tests/testpi-4.c b/testcases/realtime/func/pi-tests/testpi-4.c
index 0960c91..5a39701 100644
--- a/testcases/realtime/func/pi-tests/testpi-4.c
+++ b/testcases/realtime/func/pi-tests/testpi-4.c
@@ -81,7 +81,7 @@ pthread_mutex_t *glob_mutex;
 void *func_nonrt(void *arg)
 {
 	struct thread *pthr = (struct thread *)arg;
-	int i, j, tid = gettid();
+	int i, tid = gettid();
 
 	printf("Thread %d started running with priority %d\n", tid,
 		pthr->priority);
@@ -96,11 +96,7 @@ void *func_nonrt(void *arg)
 				tid, i, pthr->policy, pthr->priority);
 			fflush(NULL);
 		}
-		pthr->id++;
-		for (j = 0; j < 5000; j++) {
-			pthread_mutex_lock(&(pthr->mutex));
-			pthread_mutex_unlock(&(pthr->mutex));
-		}
+		busy_work_ms(1);
 	}
 	pthread_mutex_unlock(glob_mutex);
 	return NULL;
@@ -109,7 +105,7 @@ void *func_nonrt(void *arg)
 void *func_rt(void *arg)
 {
 	struct thread *pthr = (struct thread *)arg;
-	int i, j, tid = gettid();
+	int i, tid = gettid();
 
 	printf("Thread %d started running with prio %d\n", tid,
 		pthr->priority);
@@ -129,11 +125,7 @@ void *func_rt(void *arg)
 				tid, i, pthr->policy, pthr->priority);
 			fflush(NULL);
 		}
-		pthr->id++;
-		for (j = 0; j < 5000; j++) {
-			pthread_mutex_lock(&(pthr->mutex));
-			pthread_mutex_unlock(&(pthr->mutex));
-		}
+		busy_work_ms(1);
 	}
 	pthread_mutex_unlock(glob_mutex);
 	return NULL;
@@ -142,7 +134,7 @@ void *func_rt(void *arg)
 void *func_noise(void *arg)
 {
 	struct thread *pthr = (struct thread *)arg;
-	int i, j, tid = gettid();
+	int i, tid = gettid();
 
 	printf("Noise Thread started running with prio %d\n",
 		pthr->priority);
@@ -155,11 +147,7 @@ void *func_noise(void *arg)
 				pthr->priority);
 			fflush(NULL);
 		}
-		pthr->id++;
-		for (j = 0; j < 5000; j++) {
-			pthread_mutex_lock(&(pthr->mutex));
-			pthread_mutex_unlock(&(pthr->mutex));
-		}
+		busy_work_ms(1);
 	}
 	return NULL;
 }
-- 
1.7.1


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[LTP] [PATCH 6/7] realtime/testpi-4: remove thread_stop which is not used anywhere

[Gowrishankar]

From: gowrishankar <gowrishankar.m@linux.vnet.ibm.com>

testpi-4 defines THREAD_STOP which is not used anywhere in
the program.

Signed-off-by: Gowrishankar <gowrishankar.m@in.ibm.com>
Tested-by: Gowrishankar <gowrishankar.m@in.ibm.com>
Acked-by: Darren Hart <dvhltc@us.ibm.com>
---
 testcases/realtime/func/pi-tests/testpi-4.c |    3 ---
 1 files changed, 0 insertions(+), 3 deletions(-)

diff --git a/testcases/realtime/func/pi-tests/testpi-4.c b/testcases/realtime/func/pi-tests/testpi-4.c
index 5a39701..3bd5d77 100644
--- a/testcases/realtime/func/pi-tests/testpi-4.c
+++ b/testcases/realtime/func/pi-tests/testpi-4.c
@@ -73,9 +73,6 @@ int gettid(void)
 }
 
 typedef void *(*entrypoint_t)(void *);
-
-#define THREAD_STOP    1
-
 pthread_mutex_t *glob_mutex;
 
 void *func_nonrt(void *arg)
-- 
1.7.1


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[LTP] [PATCH 7/7] realtime/testpi-4: synchronization fixes for high priority noise thread

[Gowrishankar]

From: gowrishankar <gowrishankar.m@linux.vnet.ibm.com>

In a scenario where a thread other than high priority noise thread is
scheduled after the barrier, a priority inversion will not occur, defeating
the purpose of test. We need to tightly synchronize the threads so that the
noise thread always begins the test and gets preempted by the low prio thread
through the PI logic.

This change is applied on testpi-4.
Signed-off-by: Gowrishankar<gowrishankar.m@in.ibm.com>
Tested-by: Gowrishankar<gowrishankar.m@in.ibm.com>
Acked-by: Darren Hart <dvhltc@us.ibm.com>
---
 testcases/realtime/func/pi-tests/testpi-4.c |   24 +++++++++++++++++++++++-
 1 files changed, 23 insertions(+), 1 deletions(-)

diff --git a/testcases/realtime/func/pi-tests/testpi-4.c b/testcases/realtime/func/pi-tests/testpi-4.c
index 3bd5d77..63f8430 100644
--- a/testcases/realtime/func/pi-tests/testpi-4.c
+++ b/testcases/realtime/func/pi-tests/testpi-4.c
@@ -30,7 +30,9 @@
  *
  *
  * HISTORY
- *
+ *      2010-06-29 Thread synchronization changes by using
+ *                 conditional variables by Gowrishankar.
+ *                 by Gowrishankar <gowrishankar.m@in.ibm.com>
  *
  *****************************************************************************/
 
@@ -74,6 +76,8 @@ int gettid(void)
 
 typedef void *(*entrypoint_t)(void *);
 pthread_mutex_t *glob_mutex;
+static pthread_mutex_t cond_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t cond_var = PTHREAD_COND_INITIALIZER;
 
 void *func_nonrt(void *arg)
 {
@@ -85,8 +89,15 @@ void *func_nonrt(void *arg)
 	pthread_mutex_lock(glob_mutex);
 	printf("Thread %d at start pthread pol %d pri %d - Got global lock\n",
 		tid, pthr->policy, pthr->priority);
+
+	/* Wait for other RT threads to start up */
 	pthread_barrier_wait(&barrier);
 
+	/* Wait for the high priority noise thread to start and signal us */
+	pthread_mutex_lock(&cond_mutex);
+	pthread_cond_wait(&cond_var, &cond_mutex);
+	pthread_mutex_unlock(&cond_mutex);
+
 	for (i = 0; i < 10000; i++) {
 		if (i%100 == 0) {
 			printf("Thread %d loop %d pthread pol %d pri %d\n",
@@ -137,6 +148,14 @@ void *func_noise(void *arg)
 		pthr->priority);
 	pthread_barrier_wait(&barrier);
 
+	/* Give the other threads time to wait on the condition variable.*/
+	usleep(1000);
+
+	/* Noise thread begins the test */
+	pthread_mutex_lock(&cond_mutex);
+	pthread_cond_broadcast(&cond_var);
+	pthread_mutex_unlock(&cond_mutex);
+
 	for (i = 0; i < 10000; i++) {
 		if (i%100 == 0) {
 			printf("Noise Thread %d loop %d pthread pol %d "\
@@ -200,5 +219,8 @@ int main(int argc, char *argv[])
 	join_threads();
 	printf("Done\n");
 
+	pthread_mutex_destroy(glob_mutex);
+	pthread_mutex_destroy(&cond_mutex);
+	pthread_cond_destroy(&cond_var);
 	return 0;
 }
-- 
1.7.1


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Re: [LTP] [PATCH 0/7] realtime/testpi-4: code cleanup and functional changes on testpi-4

[Subrata Modak]

On Fri, 2010-07-02 at 11:55 +0530, Gowrishankar wrote: 
> Following set of patches applies code cleanup and functional changes
> in LTP realtime pi-test testpi-4. This test was not patched earlier
> when other pi-tests were fixed, with the intension of removing it
> from the suite due to similarity with testpi-1. But we decided to
> keep this test due to dynamically created global mutex lock.
> 
> Order of applying patch is:
> 
> [PATCH 1/7] realtime/testpi-4: code cleanup on pi-test 4
> [PATCH 2/7] realtime/testpi-4: reuse init_pi_mutex from librttest
> [PATCH 3/7] realtime/testpi-4: add test description
> [PATCH 4/7] realtime/testpi-4: threads need not set cpu affinity while main does
> [PATCH 5/7] realtime/testpi-4: use busy_work_ms from librttest to burn cpu cycles
> [PATCH 6/7] realtime/testpi-4: remove thread_stop which is not used anywhere
> [PATCH 7/7] realtime/testpi-4: synchronization fixes for high priority noise thread

Applied in order. Thanks.

Regards--
Subrata

> 
> Thanks,
> Gowri
> 


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