Introduction to C. Threads. Instructor: Yin Lou 02/16/2011. Introduction to C CS 2022, Spring 2011, Lecture 11

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1 Introduction to C Threads Instructor: Yin Lou 02/16/2011

2 Processes vs. Threads Processes Multiple simultaneous programs Independent memory space Independent open file-descriptors Threads Multiple simultaneous functions Shared memory space Shared open file-descriptors

3 Threads Examples Graphical User Interfaces (GUIs) The GUI is usually put on a separate thread from the app engine GUI remains responsive even if app blocks for processing Web Browser Tabs Each tab is managed by a separate thread for rendering Web pages render simultaneously Note: Google Chrome actually uses a separate process per tab

4 Threads One copy of the heap One copy of the code Multiple stacks

5 Threads One copy of the heap One copy of the code Multiple stacks Life Cycle

6 pthread #include <pthread.h>

7 pthread #include <pthread.h> Define a worker function

8 pthread #include <pthread.h> Define a worker function void *foo(void *args) { }

9 pthread #include <pthread.h> Define a worker function void *foo(void *args) { } Initialize pthread attr t

10 pthread #include <pthread.h> Define a worker function void *foo(void *args) { } Initialize pthread attr t pthread attr t attr; pthread attr init(attr);

11 pthread #include <pthread.h> Define a worker function void *foo(void *args) { } Initialize pthread attr t pthread attr t attr; pthread attr init(attr); Create a thread

12 pthread #include <pthread.h> Define a worker function void *foo(void *args) { } Initialize pthread attr t pthread attr t attr; pthread attr init(attr); Create a thread pthread t thread; pthread create(&thread, &attr, worker function, arg);

13 pthread #include <pthread.h> Define a worker function void *foo(void *args) { } Initialize pthread attr t pthread attr t attr; pthread attr init(attr); Create a thread pthread t thread; pthread create(&thread, &attr, worker function, arg); Exit current thread

14 pthread #include <pthread.h> Define a worker function void *foo(void *args) { } Initialize pthread attr t pthread attr t attr; pthread attr init(attr); Create a thread pthread t thread; pthread create(&thread, &attr, worker function, arg); Exit current thread pthread exit(status)

15 Example #include <stdio.h> #include <pthread.h> #define NUM_THREADS 5 void *print_hello(void *threadid) { long tid; tid = (long) threadid; printf("hello World! It s me, thread #%ld!\n", tid); pthread_exit(null); } int main (int argc, char *argv[]) { pthread_t threads[num_threads]; int rc; long t; for (t = 0; t < NUM_THREADS; t++) { printf("in main: creating thread %ld\n", t); rc = pthread_create(threads + t, NULL, print_hello, (void *) t); if (rc) { printf("error; return code from pthread_create() is %d\n", rc); exit(-1); } } pthread_exit(null); }

16 Thread Management pthread join(threadid, status) pthread detach(threadid)

17 Example #include <stdio.h> #include <pthread.h> #define NUM_THREADS 5 void *print_hello(void *threadid) { long tid; tid = (long) threadid; printf("hello World! It s me, thread #%ld!\n", tid); pthread_exit(null); } int main (int argc, char *argv[]) { pthread_t threads[num_threads]; int rc; long t; for (t = 0; t < NUM_THREADS; t++) { printf("in main: creating thread %ld\n", t); rc = pthread_create(threads + t, NULL, print_hello, (void *) t); if (rc) { printf("error; return code from pthread_create() is %d\n", rc); exit(-1); } } /* wait for all threads to complete */ for (t = 0; t < NUM_THREADS; t++) { pthread_join(threads[t], NULL); } pthread_exit(null); }

18 Compiling Use -pthread

19 Compiling Use -pthread Makefile CC:=gcc OPTIONS:=-O2 LIB_PATH:=-pthread SRC_DIR:=src DST_DIR:=bin default: $(CC) $(OPTIONS) $(LIB_PATH) \ $(SRC_DIR)/*.c -o $(DST_DIR)/test clean: cd $(DST_DIR); rm test

SoC drawer: Shared resource management

Page 1 of 8 SoC drawer: Shared resource management Focus on memory and I/O Sam Siewert (Sam.Siewert@Colorado.edu), Adjunct Professor, University of Colorado Summary: The goal of a system-on-a-chip (SoC)