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

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1 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 (MW). On board memory,, has a 6 bit address and 6 bit data port. There is one feature that the system has to detect known as feature. To detect feature the system has to run filter (F) and filter (F) on the data. The filters can be executed concurrently. The results of the filters (6 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 (6 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 (6 bits of data) store in memory. The tasks are listed in tables below with their labels and execution times. DSP SENSOR BUS Performance (ms) / Power Label Task DSP DSP F Filter F Filter 6 7 DF Detect Feature 5 6 CL Classification Label Task Device Performance S Sense (all samples) AD Analog to Digital (6 bits) MW/MR Write/Read (6 bits) B transfer (6 bits)

2 a) A variety of answers were acceptable here. b) Draw the minimum latency schedule for detection of the feature assuming that the trigger command comes at time ms. Assume all data processing occurs on a single 6- 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. There were multiple possible answers, depending on whether you had bus transfer occur during or before/after memory access. In the future, it will be better specified exactly how you should handle bus transfers S S S AD AD DSP F F F F F F F MW MW MR MR MR MR MW MW MW MW MR MR B B B B B B DF DF DSP CL CL MR MR MW MW MR MR MW MW B B B B c) Draw the minimum energy schedule for detection of the feature assuming that the trigger command comes at time ms. Quantify the energy savings S S S AD AD F F F F F F DSP F F F F F MW MW MR MR MR MR MW MW Mw MW B B B B B DSP DF DF DF CL CL MR MR MR MR MW MW MR MR MW MW B B B B B Performance-tuned power: 7mw Energy-tuned power: 58mw Savings: 7.%

3 Problem 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 5 B C X a) Suppose % 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. For n=, utilization = 78%. 78%-% = 65% = /5 + / + /X => X=8 Time Task A C C B B A C C A B B A C C Time Task A B B C A C A B C C B A 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, and 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, 7, etc.). Schedule the tasks with EDF. Time Task C C A B B C C A B A C C B A C C Time Task B A B C C A C C A B B C C A c) Discuss the advantages and disadvantages of EDF and RM scheduling with respect to complexity, overhead, and efficiency.

4 Problem You are given five tasks (T-T5) and five different hardware implementations: HW, HW, HW, and HW (each costing $5, $5, $5, and $ respectively) and a processor P (costing $5). The table below shows the time it takes to run each task at each HW/P unit in seconds. The task graph deadline is 5 seconds. Show a feasible partitioning of tasks among HW elements and the processor. List the minimum execution time and minimum cost schedules. What is the cheapest schedule that meets the deadline of the task graph? T T T T T5 T H H H H P SOLUTION Minimum Cost: Task T T T T T5 HW H H H H H Cost: $5 Time: = 86 Minimum Execution Time: Task T T T T T5 HW H H H P H Cost: $9 Time: MAX(5,) + 8 = 9 Min Cost - Meet deadline: Task T T T T T5 HW H H H H H Cost: $ Time: MAX(9,) + 8 = 5

5 Problem Show the time evolution of the following distributed events using a) Lamport's logical time b) Vectored time P P P SOLUTION Lamport P 6 P 5 P 6 Vectored time P P P 5 5

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 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