update perf bug...

study/patch/mutex/lock_bug.c

@@ -92,14 +92,14 @@ int main(int argc,char** argv){
         pthread_t id1;
         pthread_t id2;
 
-        struct args arg1 = { .sleeptime = 1000000, .cpu = 0 };
-        struct args arg2 = { .sleeptime = 1000000, .cpu = 0 };
+        struct args arg1 = { .sleeptime = 10000000, .cpu = 0 };
+        struct args arg2 = { .sleeptime = 10000000, .cpu = 0 };
 
         LOCK_INIT( );
 
 
         printf("MAIN pid = %d\n", getpid( ));
-
+	getchar( );
 
         pthread_create(&id1, NULL, print_msg, &arg1);
         pthread_create(&id2, NULL, print_msg, &arg2);

study/patch/perf/Makefile

@@ -0,0 +1,17 @@
+target=bug_fork
+
+all:$(target)
+
+bug_fork:bug_fork.c
+	$(CC) $^ -o $@ $(LDFLAGS) -lpthread -DMUTEX -static
+	@echo "mutex lock..."
+
+%.o : %.c
+	$(CC) -c $^ -o $@  $(CFLAGS) $(DEFINES)
+
+%.o	: %.cpp
+	$(CXX) -c $^ -o $@  $(CFLAGS) $(DEFINES)
+
+clean :
+	rm -rf *.o
+	rm -rf $(target)

study/patch/perf/README.md

@@ -0,0 +1,51 @@
+
+1	perf record sched:sched_wakeup_new ./bug_fork
+
+perf/ftrace : Fix repetitious traces when specify a target task
+
+
+
+When use perf to trace the sched_wakeup and sched_wakeup_new tracepoint, there is a bug that output the same event repetitiously, It can be reproduced by :
+
+
+```cpp
+perf record -e sched:sched_wakeup ./bug_fork
+OR
+./bug_fork # pid 1052
+perf record -e sched:sched_wakeup -p 1052
+```
+
+```cpp
+swapper     0 [000]  3854.085452:     sched:sched_wakeup: comm=perf pid=1101 prio=120 target_c
+pu=000
+swapper     0 [000]  3854.085473:     sched:sched_wakeup: comm=perf pid=1101 prio=120 target_c
+pu=000
+bug_fork  1101 [000]  3854.089933: sched:sched_wakeup_new: comm=bug_fork pid=1102 prio=120 targ
+et_cpu=001
+bug_fork  1101 [000]  3854.089950: sched:sched_wakeup_new: comm=bug_fork pid=1102 prio=120 targ
+et_cpu=001
+bug_fork  1101 [000]  3854.089959: sched:sched_wakeup_new: comm=bug_fork pid=1102 prio=120 targ
+et_cpu=001
+bug_fork  1102 [001]  3854.092185:     sched:sched_wakeup: comm=rcu_sched pid=8 prio=120 target
+_cpu=001
+swapper     0 [000]  3854.665213:     sched:sched_wakeup: comm=bug_fork pid=1101 prio=120 targ
+et_cpu=000
+swapper     0 [000]  3854.665253:     sched:sched_wakeup: comm=bug_fork pid=1101 prio=120 targ
+et_cpu=000
+
+```
+
+Some events not only monitor the current task, but also specify a target task. For example, the sched_wakeup/sched_wakeup_new tracepoint will be caught when the current task wakeup the target task which we traced on.
+
+the commit bed5b2 has designed a method to trace these events which specify a target task. Due to these events are registered for each CPU(percpu), so perf_swevent_event will match the event multiple times, the number of repetitions is just the number of CPUs.
+
+On the other hand perf_tp_event will only match an event event at a time, so we will return after an event matched.
+
+
+
+2	perf sched record 支持 -p 1 但是不支持 task
+
+3	perf/trace record 显示current有时候不正常, 只显示pid, 不显示comm
+	stat_runtime	current进程不正确
+
+4	pr_debug 不支持 arm64 和 arm32

study/patch/perf/bug_fork.c

@@ -0,0 +1,32 @@
+/*
+ *  fork_test.c
+ *  version 1
+ *  Created on: 2010-5-29
+ *      Author: wangth
+ */
+#include <unistd.h>
+#include <stdio.h>
+int main ()
+{
+	pid_t fpid; //fpid表示fork函数返回的值
+	int count=0;
+
+	while( 1 ) {
+		fpid=fork();
+
+		if (fpid < 0)
+			printf("error in fork!");
+		else if (fpid == 0) {
+			printf("Child pid = %d\n", getpid( ));
+			exit(0);
+		}
+		else {
+			if (waitpid(fpid, NULL, 0) != fpid)		/* wait for first child */
+				perror("waitpid error");
+			printf("Parent PID = %d\n", getpid( ));
+			sleep(20);
+		}
+	}
+
+	return 0;
+}

study/patch/perf/sem_test.c

@@ -0,0 +1,37 @@
+// http://blog.csdn.net/jianchaolv/article/details/7544316
+#include <stdio.h>
+#include <stdlib.h>
+#include <semaphore.h>
+#include <pthread.h>
+
+
+sem_t sem_a;
+void *task1();
+
+int main(void){
+        int ret = 0;
+        pthread_t thrd1;
+        pthread_t thrd2;
+
+	printf("pid = %d\n", getpid( ));
+	sem_init(&sem_a,0,1);
+	ret=pthread_create(&thrd1,NULL,task1,NULL); //创建子线程
+	ret=pthread_create(&thrd2,NULL,task1,NULL); //创建子线程
+
+	pthread_join(thrd1,NULL); //等待子线程结束
+	pthread_join(thrd2,NULL); //等待子线程结束
+
+}
+
+void *task1()
+{
+	int sval = 0;
+	while(1)
+	{
+		sem_wait(&sem_a); //持有信号量
+		sleep(1); //do_nothing
+		sem_getvalue(&sem_a,&sval);
+		printf("tid = %ld, sem value = %d\n", pthread_self( ), sval);
+		sem_post(&sem_a); //释放信号量
+	}
+}