REACT™ for LINUX®

SGI has been an industry leader in the real-time arena for over a decade. SGI is actively participating in the Linux community, identifying hold-offs and submitting modifications that result in better latencies. SGI delivers expertise and support and setup information that can't be found anywhere else. A white paper is available: Real-time Capabilities for Linux (PDF 3.2K)

Now Supporting SGI® Altix® XE Systems in addition to Itanium systems

Unique to the SGI® Altix® server systems are:

  • Large memory support
  • 30 µs max interrupt response time on 2-64 cpu systems
  • Bandwidth and latency advantages with NUMAlink® technology
  • Flexible scaling, both up and down
  • Independent scaling of cpu, memory and I/O
  • Hardware dependent external interrupt capability (IO9 card required)
  • User level interrupts
  • Frame Rate Scheduler
  • High Resolution Timers/Clock
  • Kernel barrier feature (Not available for X86 systems)
  • sgi-shield - maximum isolation capability - eliminates jitter - allows users to turn off timer interrupts on the real-time cpu(s)
  • SGI Linux Trace - debug kernel with the capability of generating traces for kernel events such as interrupt handling, scheduling and system calls. The recorded trace events are then viewable with a tracevisualizer (gui) tool, allowing users to analyze how kernel behavior impacts the execution of applications
  • Dynamic reconfiguration capability
  • ligsgirt - userspace library that contains IRIX compatibility routines
  • config tools (GPL) - including dynamic reconfig capability and bootcpuset api)

REACT 5.3 Real-Time for Linux

REACT 5.3 Real-time for Linux is designed to run on SUSE® Linux Enterprise Server 10, SP1 and SGI ProPack™5, SP 3 for Linux. SUSE Linux Enterprise provide kernel support allowing for an average real-time interrupt response time of 4-6 µ with 30 µ maximum interrupt response time on a properly configured 2-64 p SGI system.

Disk space requirement for the REACT is less than 500 Mbytes.

Features in Release 5.3 include:

  • SLT Enhancements
    • Additional kernel traces, (Including FRS)
    • Tracedaemon now controlled from Tracevisualizer
    • More control of trace time and thread placement
    • Enhanced GUI
      • Examine all cpus in one graph
      • cpu filtering
      • Time Display and measuring improvements
    • Ability to be run by non-root user
  • Capabilities Support
    • The capability tools (captools) package implements Linux security capabilities access and manipulation functions, going beyond that provided by "stock" Linux. Captools enables granting of capabilities that are normally associated with root to normal.

Requirements/Dependencies

  • SUSE™ LINUX Enterprise Server 10, SP1 base and SGI ProPack™5, SP 3
  • Systems config boot-time setup

SGI Altix Real-Time Foundation

Interrupt response time is the time that passes between the instant when a hardware device raises an interrupt signal, and the instant when --interrupt service completed--the system returns control to a user process. The goal is to sustain minimum interrupt response times - maximum is 30 microseconds.

  • At system startup, each cpu designated by the customer as a real-time cpu is restricted from running any threads except those threads that are specifically assigned to it (and only it). This includes kernel threads that are bound only to that cpu, as well as any user threads that is later designated to run on that cpu.
  • Each of those cpus is isolated from the effects of scheduler load-balancing, which was found to have significant effects on latency.