CSE 237A. Prof. Tajana Simunic Rosing HW #2. Due: February 1st, 2011

Size: px

Start display at page:

Download "CSE 237A. Prof. Tajana Simunic Rosing HW #2. Due: February 1st, 2011"

Andra Brown
6 years ago
Views:

1 CSE 237A Prof. Tajana Simunic Rosing HW #2 Due: February 1st, 2011 Problem 1 Consider the following sensor network platform. A PZT device senses a wave sample (S), which is then digitized (AD) and stored for processing (MW). On board memory,, has a 16 bit address and 16 bit data port. There is one feature that the system has to detect known as feature 1. To detect feature 1 the system has to run filter 1 (F1) and filter 2 (F2) on the data. The filters can be executed concurrently. The results of the filters (16 bits of data each) are then stored at distinct memory locations. Thereafter, a detection algorithm is executed on this data, and the outcome of the detection (16 bits of data) is stored in memory. Finally, a classifier is run using the detected features to infer the state of the environment around the sensor, with its output (16 bits of data) store in memory. The tasks are listed in tables below with their labels and execution times. SENSOR BUS Performance (ms) / Power (mw) Label (perf) (mw) (perf) (mw) (perf) (mw) F1 Filter F2 Filter DF Detect Feature CL Classification Label Device Performance S Sense (all samples) 3 AD Analog to Digital (16 bits) 2 MW/MR Write/Read (16 bits) 2 B transfer (16 bits) 1

2 a) Draw the task graph for this sensing platform. Make sure to pay careful attention to dependencies between tasks and hardware platforms. You may assume that DSPs and the processor have large enough data caches to hold their input data and the results of every task they perform. Use labels provided to you in the tables. b) Draw the minimum latency schedule for detection of the feature assuming that the trigger command comes at time 0ms. Assume all data processing occurs on a single 16- bit data sample. Put appropriate task labels in the tables provided below to show which tasks run on what HW. Time is given in ms c) Draw the minimum energy schedule for detection of the feature assuming that the trigger command comes at time 0ms. Quantify the energy savings

3 Problem 2 A periodic control task C is executed on a CPU, which executes also two other tasks, A and B. Assume that period = deadline. The tasks have the following characteristics: WCET Period A 1 5 B 2 10 C 2 X a) Suppose 13% of the CPU utilization is reserved for other activities. Derive the minimum task period for the control task C that guarantees schedulability of A, B, and C with RM. Show the schedule in the table below. Time Time b) Due to special design constraints task C has to be executed every 6 time units. Assume that start times for tasks A,B & C are 2,1 and 0 respectively. From that point on they repeat with period shown in the table (e.g. if task A has the highest priority, it would be scheduled at time 2, 7, 12 etc.). Schedule the tasks with EDF. Time Time c) Discuss the advantages and disadvantages of EDF and RM scheduling with respect to complexity, overhead, and efficiency.

4 Problem 3 You are given five tasks (T1-T5) and five different hardware implementations: HW1, HW2, HW3, and HW4 (each costing $15, $25, $5, and $10 respectively) and a processor P (costing $35). The table below shows the time it takes to run each task at each HW/P unit in seconds. The task graph deadline is 50 seconds. Show a feasible partitioning of tasks among HW elements and the processor. List the minimum execution time and minimum cost schedules. Note that the minimum cost schedule may miss the deadline! What is the cheapest schedule that meets the deadline of the task graph? T1 T2 T3 T4 T5 T H1 H2 H3 H4 P Problem 4 Show the time evolution of the following distributed events using a) Lamport's logical time b) Vectored time P1 P2 P3

5 Problem 5 Your job is to design a new small (and cheap!) body-worn device for elderly patients in hospitals. It should communicate wirelessly with a Zigbee radio interface, and is capable of the following major tasks: I. Regularly monitor the patient's heart rate and report it to a centralized location II. If the heart rate is detected to be too low or high for a given patient, sound an alarm III. Detect changes in the patients posture (sitting up, lying down, etc) IV. Detect that a patient has suddenly fallen and send an alarm to the hospital staff V. Make a warning sound when the battery has less than 10% left VI. Sounding an alarm includes sending a notification to the patient s cell phone via Zigbee and sending a message that notifies the hospital staff that the patient needs help VII. If the patient is out of range and the device cannot communicate with the hospital network, dial 911 on the patient's cell phone Outline how you would perform the design process. Specifically: A. Draw a block diagram of HW components you d need to use, explain why you selected the given configuration and how communication between components should be implemented B. Discuss what SW you would need to implement and what kind of OS, if any, might you use? C. Is there a need for computation/communication scheduling? If so, what schedulers are appropriate? D. What kinds of sensors/actuators do you need? How do you interface with them? What kinds of AD/DA converters might you need? Comment on their characteristics. E. Is there a need for open and/or closed loop control in the design, and if so, describe where and how it would be implemented Problem 6 Analyze what task/thread scheduling algorithms are used in the systems listed below. Explain why particular schedulers were chosen and what applications they work best for. a) Linux kernel (2.6.35) b) RTLinux c) VxWorks d) TinyOS e) Symbian OS f) Android OS g) ios

6 Problem 7 With one other student, go through the steps detailed in compile_guide.pdf (found on the course website). During these steps you will complete the following: Make minor changes to the kernel (code/files provided to you) Compile the kernel with the modified code Compile the complete Android system As deliverables for this part of the project, each group must include screenshots of their console that clearly shows the output for each of the following steps: 1. After compiling the kernel and the file zimage has been produced 2. After compiling the Android image and update.cm-xxxxx-signed.zip is produced (where XXXXX is a version number) 3. After completing the steps to unpack, modify, and repack the Android image so that it contains your custom kernel Clearly state the name of the student you worked with at the beginning of your HW2 solutions. BOTH team members must include the screenshots in their assignment.

CSE 237A. Prof. Tajana Simunic Rosing HW #2. Due: February 1st, 2011

CSE 237A. Prof. Tajana Simunic Rosing HW #2. Due: February 1st, 2011 CSE 7A Prof. Tajana Simunic Rosing HW # Due: February st, Problem Consider the following sensor network platform. A PZT device senses a wave sample (S), which is then digitized (AD) and stored for processing