A Methodology for Using Traffic Generators with Real-Time Constraints. Avinash Mehta Sr. Research and Development Engineer Synopsys India Pvt. Ltd.

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1 A Methodology for Using Traffic Generators with Real-Time Constraints Avinash Mehta Sr. Research and Development Engineer Synopsys India Pvt. Ltd. 1

2 Agenda Introduction Real time traffic challenges Proposed Solution Examples Conclusions Accellera Systems Initiative 2

3 Introduction Why Early Architecture exploration and analysis? Accellera Systems Initiative 3

4 SoC Performance Analysis Methodologies in Deployment Interconnect & Memory Subsystem Introduction HW-SW Performance Validation Trace-driven Workloads SW-driven Workloads Traffic scenario Traffic scenario Software Software FRBM FRBM CA PSP CA PSP Interconnect Memory Subsystem Explore Optimize Validate Accellera Systems Initiative 4

File Reader Bus Master (FRBM) Trace-Driven Traffic

subsystems are represented by FRBM Easily configurable to

stl Assign to Simulate Traffic Files FRBM-based Performance

5 File Reader Bus Master (FRBM) Trace-Driven Traffic Generation Record traces or generate traces IPs and subsystems are represented by FRBM Easily configurable to mimic real world IPs A.stl C.stl B.stl Assign to Simulate Traffic Files FRBM-based Performance Model High Simulation early stage of development Analysis & Exploration Accellera Systems Initiative 5

6 Socket Transaction Language (STL) Socket Transaction Language (STL) is a scripting language for generating OCP input traffic. Basic commands, Macro and behavioral statements. The format for a basic command is: [cycle:] [tid[/cid]] cmd[/reqinfo] [as/]addr [(be)] [data [(mask)]] Examples read 0x0 0xFF 10: write 0x10 0xFF optional writenonpost 0x10 0xAA (0xF0) Accellera Systems Initiative 6

7 Real-time computing Systems subject to a "real-time constraint", for example operational deadlines Real-time systems must guarantee response within specified time constraints, often referred to as "deadlines". Examples: Mission critical applications Control of fly-by-wire aircraft Anti-lock brakes Image/Video Processing Accellera Systems Initiative 7

8 Real time traffic challenges RT Initiators should exhibit the following characteristics: A deadline of completing a task. A deadline to start the next task. Delay in one task does not impact the next task. To comply with the above constraints, FRBM would need to support the following: Creation of task boundaries. Constraints of start time and stop time of the task. Analysis of the missing deadlines. Accellera Systems Initiative 8

9 Proposed Solution The idea is to divide the re-playable format into frames A frame corresponds to a task Each frame will have clearly marked start and end points Each frame is associated with a timeout period & timer name Support for nested frames for analysis of finer deadlines Accellera Systems Initiative 9

10 Examples Example traffic file which can be replayed on FRBM start_timer <timer_1, +30> { bwritenonpost 0x0 0xAA idle 10 bwritenonpost 0x5 0xFF } Enhancement Enhancement Specification Accellera Systems Initiative 10

11 DUT_1 Max Outstanding Limit:3 Accellera Systems Initiative 11

12 Results Timer Activity Txn Drop Stats Accellera Systems Initiative 12

13 DUT_2 Max Outstanding Limit:10 Accellera Systems Initiative 13

14 Results Timer Activity Headroom Stats Accellera Systems Initiative 14

15 Using nested timer blocks start_timer <timer_1, +30> { bwritenonpost 0x0 0xFF bwritenonpost 0x1 0xBB } bwritenonpost 0x99 0xEE bwritenonpost 0x100 0xAA start_timer <timer_1, +30> { start_timer <timer_1.1, +10> { bwritenonpost 0x0 0xFF bwritenonpost 0x10 0xAA }. start_timer <timer_1.1, +10> { bwritenonpost 0x91 0xFF bwritenonpost 0x100 0xAA } } Accellera Systems Initiative 15

16 Single Timer Last few txns drop Accellera Systems Initiative 16

17 Nested Timers Txn drop Txn drop Txn drop Accellera Systems Initiative 17

18 Conclusions Deadline sensitive traffic generator. Easily analyze the performance of the system Headroom cycles in case where system is over designed. Number of transactions dropped in case where system is under designed. Finer deadline handling using nested frames. Easily analyze timer and traffic views, showing activity of nested timers and transaction. Accellera Systems Initiative 18

19 References [PA-MCO] Platform Architect-Multi Core Optimization [OCP-IP STL] accellera.org, Socket Transaction Language Accellera Systems Initiative 19

20 Questions Accellera Systems Initiative 20

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