From c1f4bba6b2576f42bf0ad0c24ac13c35b5ee1964 Mon Sep 17 00:00:00 2001
From: Ajay Mohan <ajmohan@ucsd.edu>
Date: Sun, 6 Mar 2016 21:17:18 -0800
Subject: [PATCH] Thread Ctx Switches

---
 memory/thd_ctx_mtx.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 memory/thd_ctxsw.c   | 53 +++++++++++++++++++++++++++++++
 rasperf.h            | 15 +++++++--
 3 files changed, 155 insertions(+), 2 deletions(-)
 create mode 100644 memory/thd_ctx_mtx.c
 create mode 100644 memory/thd_ctxsw.c

diff --git a/memory/thd_ctx_mtx.c b/memory/thd_ctx_mtx.c
new file mode 100644
index 0000000..7dafb9a
--- /dev/null
+++ b/memory/thd_ctx_mtx.c
@@ -0,0 +1,89 @@
+#include<stdio.h>
+#include<stdlib.h>
+#include<unistd.h>
+#include<pthread.h>
+#include<sys/time.h>
+#include "rasperf.h"
+#define NUM_THREADS 2
+#define ITERATIONS 1000
+
+pthread_mutex_t LOCK;
+pthread_mutex_t TRIGGER;
+pthread_cond_t COND;
+volatile unsigned int cs_count = 0;
+
+// Uptil now TRIGGER WAS LOCKED AND THEN RELEASED
+void * function(void *id){
+    int t_id = *(int *)id;
+
+    // Wait for trigger from parent
+    pthread_mutex_lock(&TRIGGER);
+    pthread_mutex_unlock(&TRIGGER);		// So that both start at the same time
+    // Get lock
+    pthread_mutex_lock(&LOCK);			//only one thread passes in
+
+    // Wake up other thread if context switch count is greater than 0
+    if (cs_count > 0){
+        pthread_cond_signal(&COND);
+    }
+
+    while(cs_count < ITERATIONS) {
+
+        // Wait for other thread to wake up us
+        cs_count++;					//Increment cs count
+        pthread_cond_wait(&COND, &LOCK);		//release LOCK and wait for COND
+
+        // wake up other thread
+        pthread_cond_signal(&COND);        
+    }
+    pthread_mutex_unlock(&LOCK);
+    pthread_exit(NULL);
+}
+
+
+int main(){
+
+    pthread_t threads[NUM_THREADS];
+    int rc, i,id1=1, id2=2;
+    time start, end;
+    int t;
+    
+    pthread_mutex_init(&LOCK, NULL); 		// to protect CS
+    pthread_mutex_init(&TRIGGER, NULL);		//This is to start at the same time
+    pthread_cond_init(&COND, NULL);		// to wake each other
+
+    pthread_mutex_lock(&TRIGGER);		//to stop the threads we are going to create		
+					
+
+    rc = pthread_create(&threads[0], NULL, function, (void*)&id1);	//create first thread
+    if (rc){
+        perror("Thread creation failed!");
+    }
+    rc = pthread_create(&threads[1], NULL, function, (void*)&id2);	//create second thread
+    if (rc){
+        perror("Thread creation failed!");
+    }
+
+    getTime(start);				// start time
+    pthread_mutex_unlock(&TRIGGER);		// by releasing the trigger start the threads
+
+    // Wait for threads to finish
+    for(i=0; i<NUM_THREADS; i++) {
+        pthread_join(threads[i], NULL);
+    }
+
+    getTime(end);
+    t = diff(end, start);
+    //printf("%f\n",(t/(CPU_FREQ*ITERATIONS)) - TIME_MEASUREMENT_OVERHEAD);
+    
+    printf("Time Taken %d",t);
+    // Clean up
+    pthread_mutex_destroy(&LOCK);
+    pthread_mutex_destroy(&TRIGGER);
+    pthread_cond_destroy(&COND);
+    pthread_exit(NULL);
+}
+
+
+ 
+
diff --git a/memory/thd_ctxsw.c b/memory/thd_ctxsw.c
new file mode 100644
index 0000000..593d101
--- /dev/null
+++ b/memory/thd_ctxsw.c
@@ -0,0 +1,53 @@
+#define _GNU_SOURCE
+#include<sched.h>
+#include "rasperf.h"
+#include<stdio.h>
+#include<unistd.h>
+#include<stdlib.h>
+#include<signal.h>
+#define STACK_SIZE 4096
+int pipe_fd[2], tid1, tid2;
+char buffer[10];
+int reader(void* arg);
+int writer(void* arg);
+int controller(void *arg)
+{
+    void *tid1_stack = malloc(STACK_SIZE);
+    void *tid2_stack = malloc(STACK_SIZE);
+    tid1 = clone(&writer, tid1_stack+STACK_SIZE, SIGCHLD|CLONE_SIGHAND|CLONE_FS|CLONE_VM|CLONE_FILES|CLONE_THREAD, NULL);
+    tid2 = clone(&reader, tid2_stack+STACK_SIZE, SIGCHLD|CLONE_SIGHAND|CLONE_FS|CLONE_VM|CLONE_FILES|CLONE_THREAD, NULL); 
+    return 0;
+}
+int reader(void* arg)
+{
+    read(pipe_fd[0], buffer, 1);
+    return 0;
+}
+int writer(void* arg)
+{
+    write(pipe_fd[1], "a", 1);
+    return 0;
+}
+int main(){
+
+	unsigned int regr;
+	time start, end;
+	unsigned int avg;
+	int status, i;
+	void *child_stack = malloc(STACK_SIZE);
+	int thread_pid;
+
+	//asm volatile("mrc p15, 0, %0, c9, c14, 0" : "=r" (regr));
+	//printf("regr: %x\n", regr);
+	
+	//initialize communication pipe
+	for (i = 0; i < 1000; i++)
+	{
+		getTime(start);
+		thread_pid = clone(&controller, child_stack+STACK_SIZE, SIGCHLD|CLONE_SIGHAND|CLONE_FS|CLONE_VM|CLONE_FILES|CLONE_THREAD, NULL);
+		waitpid(thread_pid, 0, 0);
+		getTime(end);
+		printf("\nTime Taken %d", diff(end,start));
+	}
+	return 0; 
+}    
diff --git a/rasperf.h b/rasperf.h
index 57422ad..e0e76b4 100644
--- a/rasperf.h
+++ b/rasperf.h
@@ -1,6 +1,9 @@
 #ifndef __RASPERF_H__
 #define __RASPERF_H__
-
+#define PI 1
+#define x86 0
+#if defined(PI) && PI
+#define time unsigned int
 #define getTime(var) \
 	asm volatile (\
 	"mrc p15, 0, %0, c9, c13, 0":\
@@ -9,5 +12,13 @@
 	asm volatile (\
 	"mrc p15, 0, %0, c9, c14, 0":\
 	"=r" (var));
-
+#define diff(end, begin) (end - begin)
+#endif
+#if defined(x86) && x86
+#define time struct timeval
+#define getTime(var) gettimeofday(&var, NULL)
+#define diff(end, begin) \
+	(end.tv_sec*1e6+end.tv_usec - begin.tv_sec*1e6+ begin.tv_usec)
+#endif
+#endif
 
-- 
1.9.1