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An Embedded Linux System Based on PowerPC YE Mei yem@ihep.ac.cn Experimental Physics Center Institute of High Energy Physics. Outline. Introduction The Readout System Overview of the Testbed Design and Implementation Conclusions. Introduction.

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  1. An Embedded Linux System Based on PowerPCYE Meiyem@ihep.ac.cnExperimental Physics Center Institute of High Energy Physics

  2. Outline • Introduction • The Readout System • Overview of the Testbed • Design and Implementation • Conclusions

  3. Introduction • 12 years since the commission of the BES at BEPC • Both machine and detector have undergone the upgrade • The peak luminosity of 1033cm-2sec-1 • The estimated event rate: about 4000Hz at J/ψpeak • The new electronics will up to higher event rate and has much more noise environment. • The DAQ system will adopt embedded real time operation system(RTOS) and corresponding programming techniques to fit the readout requirement of the Front-End Electronics(FEE).

  4. The Readout System • Designed to adopt Motorola’s PowerPC • Real-time operation system : Multi-level parallel data collecting and processing schemes • Work with the readout electronics: performs initialization and calibrations of sub-systems; collect, pre-process and transfer data • Several readout crates are connected to a readout PC through fast Ethernet, thus constituting a readout branch • All the readout branches are connected to the online computer farm through gigabit switch • The events are recorded in persistent media.

  5. The Readout System • The main tasks of the readout system are: • collecting event data from the front-end electronics after Level 1 trigger • pre-processing and assembling • transferring data fragments from the VME readout crate to the readout PC

  6. Benefit from Embedded Linux • High price of the commercial RTOS: VxWorks, LynxOS • The possibility of using the embedded real-time Linux as the operating system of the readout system. In comparison with VxWorks (Single Seat) : 1:3

  7. Debug Overview of the Development Environment Online Software , Linux Gigabit Ethernet TimeSys SDK & IDE Env. RH 7.3 ~ 9.0 Readout PC RH 7.3 ~ 9.0 Host X86 100M Ethernet FEEs PowerPC: MVME5500 TimeSys Analysis Tools Windows TimeSys Linux Target Host X86

  8. The Readout System To accomplish above tasks, the testbed system must be designed to have the following functions: • To collect data from the VME readout modules (ADC and TDC) at high speed and full utilize the VME bus bandwidth; • To set up the multi-level buffering techniques that solve the “bottleneck” problem caused by the VME data fragments assembling and the network transmission; • To use the necessary task synchronization strategy and software protocols that ensure the correct parallel processing; • To build the effective channel between the kernel module and the user module; • To simulate the Front-End Electronics modules to generate the VMEbus trigger and Monte Carlo data; • To establish the APIs between the readout code and the online software.

  9. PowerPC Intro — MVME5500 • Features: • MPC7455 microprocessor at 1 GHz • 2MB of L3 cache • 100 MHz front-side bus • 256/512MB of on-board ECC SDRAM —expandable up to 1GB with optional memory expansion module • 40MB Flash memory • Dual IEEE P1386.1 compatible 32/64-bit 33/66 MHz PMC expansion slots • 64-bit PCI expansion mezzanine connector allowing up to four more PMCs • Dual serial ports • 10/100 and Gb Ethernet interfaces • Single VME slot when configured with PMC modules and memory mezzanine • MVME51xx I/O compatibility • MOTLod firmware

  10. PowerPC Intro — MVME2431 • Motorola 2400 Series:MVME2431 • CPU:MPC750 PowerPC(350MHZ) • Up to 1MB of backside L2 cache • 32MB SDRAM • 8MB of on-board Flash(bankB), 1MB of socketed Flash(bankA), • 10/100BaseT Ethernet • One serial port • PPCBug:evaluation and debugging tool

  11. JTime Add-on Standard Linux/POSIX APIs Reservations Add-on Prioritizable Interrupt Handler Fully Preemptible Linux GPL Kernel TimeSys Linux RTOS Overview … Linux App Linux App Constant Time Scheduler • RTOS Modules • POSIX Real-Time • Priority Inversion Control KLM • High Resolution Timer KLM Prioritizable Soft-IRQ (aka Bottom Half)

  12. Reservations Add-on • Loadable kernel module • CPU and Network resource management • JTime Add-on • RTSJ compliant Java Virtual Machine • GUI-Based Tools • TimeStorm Linux Development Suite • TimeStorm IDE • TimeTrace TimeSys Linux RTOS:Software Development Kit (SDK) • 2.4.21 Linux Kernel • GPL Performance Improvements • RTOS Kernel Loadable Modules • Certified drivers for hardware • CGL and CE Linux features • Certified Toolchains • gcc/g++ 3.2, gdb 5.3, glibc 2.2.5, binutils 2.13, KGDB 5.2.1 • Windows or Linux hosting TimeSys Linux RTOS SDKs • Root File System • CGL & CE Linux Packages • 100+ Packages & 196 Tools

  13. Professional & Designer Editions: Integrated with TimeStorm IDE • Full-featured IDE for any Linux • Kernel, driver and application development, debug, and deployment • Linux & Windows based IDE • Utilizes standard tools • GCC, GDB, Make, …… • Foundation for all TimeStorm Tools • Built on Eclipse framework • Extensibility: 350+ open-source and commercial plug-ins available • Eclipse v2.1 and CDT v1.0.1 Easily create, download and debug C/C++/Java code

  14. Professional & Designer Editions: Integrated with TimeTrace • Graphically represent exactly what is happening within a system. • Critical events unfold within an application • Context switches • Mutex locks/unlocks • Scheduling events • Timer events • Many others including user defined • Dynamically instrumented on “production” code!

  15. Measurement Technique • Test the performance of the system such as: • The time spend on VME read and write operations • The speed of DMA read operation • System latency when receive interrupt • Network throughput and the CPU rate on network transfers • Integrated Test: Block/Signal • Response Jitter

  16. System Latency

  17. Online Software DATA VMEBus Shake Hand DATA DMA PACK NET RngBuf RngBuf Data Size Data Size Signal Trig. Handler MVME5500 Shake Hand Front End (MVME2431) DATA Readout Module

  18. Result with Block Module • Intr(blk) +DMA +Pack+Net • msg_q(2)+rngBuf(2) • 1 Trig. Event Rate : 10300 CPU = 72.8% • 16 Trig. Event Rate : 18157 CPU = 47.4% • VxWorks Ref. • 1 Trig. Event Rate : 11600 CPU = 88% • 16 Trig. Event Rate : 16000 CPU = 84%

  19. The Result with Signal Module • Intr(sig)+Pack+DMA+Net • msg_q(2)+rngBuf(2) • 1 Trig. Event Rate : 8190 CPU = 68.3% • 16 Trig. Event Rate : 18186 CPU = 51.4%

  20. The Result with IPC Message Queue • Intr(sig)+Pack+DMA+Net • Msg_IPC(2)+rngBuf(2) • 1 Trig. Event Rate : 8287 CPU = 68.0% • 16 Trig. Event Rate : 18100 CPU = 53.0%

  21. Jitter Tests of Real-Time OS Performance (Under Heavy Idle Task and Network Load) • Intr(sig)+DMA+Net+rngBuf(1) • Intr(blk)+DMA+Net+rngBuf(1) • Exit When the rngBuf full

  22. Desktop OS Commercial Unix Embedded Linux Real-Time Unix Widely-Used RTOS TimeSys Linux/Real-Time Benchmark from TimeSys/Linux RTOS

  23. Long Time Test Run Net: 12MB/s 8000Hz,20Hrs 10000Hz,17Hrs 18000Hz,62Hrs

  24. Conclusions • As experiment discussed above the strategy using the embedded real-time Linux as the operating system of the PowerPC is able to fit the essential requirement of the readout system. • In addition to the task of readout and net transmission there is still enough CPU idle to ensure the stabilization of the system. • Considering the nice price and performance of the TimeSys Linux/real-time the DAQ could take into account the possibility of adopting the real-time Linux.

  25. Thanks27th Sep. 2004Congress CentreInterlaken, Switzerland

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