TimeSys issues position statement on MontaVista real-time
Sep 14, 2000 — by LinuxDevices Staff — from the LinuxDevices Archive — viewsTimeSys has joined the chorus of responses to MontaVista Software's recent press release entitled “MontaVista First to Deliver Hard Real-Time Linux” [story]. Following is the text of the TimeSys statement . . .
on “Hard Real-Time Extensions”
A competitor of TimeSys recently announced that they are “the first to deliver hard real-time Linux”. TimeSys would like to point out that this statement is false based on the following facts:
- TimeSys has delivered to the market in May 2000, our TimeSys Linux/RT product that incorporates direct extensions to the Linux kernel that provides a strong platform for building hard real-time applications. These kernel extensions included support for guaranteed and deadline-aware CPU reservations with enforcement, 256 levels of fixed-priority scheduling, support for priority inheritance, support for periodic tasks, and high-resolution clocks and timers. These Linux kernel extensions, called the “Resource Kernel (RK)”, have been downloadable from our web-site (www.timesys.com) since May 2000. RK extensions are binary-compatible with Linux by definition and can actually allow Linux applications to be given real-time and QoS guarantees without accessing or modifying the application source code.
- It is well-known in the real-time systems community that fixed-priority scheduling combined with priority inheritance support and high-resolution timers is sufficient to build hard real-time systems. In fact, the most popular framework for building hard real-time systems is called RMA (Rate-Monotonic Analysis), which requires only these primitives. RMA is the ONLY framework supported by all major standards in the real-time systems marketplace, including Real-Time Extensions to POSIX, Real-Time Java, Real-Time CORBA, Real-Time UML, Ada 83 and Ada95. The competition does NOT support QoS guarantees, priority inheritance, high-resolution timers or periodic tasks.
- In addition to the direct Linux kernel extensions described in (1) above, TimeSys Linux/RT 1.0 and 1.1 also includes the RTAI layer from DIAPM, Italy. The RTAI layer is an independent higher-priority real-time kernel that runs below Linux. TimeSys Linux/RT includes both this higher-performance (but non-Linux-binary-compatible RTAI) layer AND the Resource Kernel extensions. The two are mutually exclusive but both support hard real-time applications.
- TimeSys Linux/RT not only supports hard real-time applications on uniprocessor platforms but also does so on shared-memory multiprocessors. This SMP hard real-time support is currently being tested by beta-customers and is scheduled to ship by the end of September, 2000. This support was announced at LinuxWorld last month. The competition does not support hard real-time on SMP architectures.
- TimeSys has just announced extensions to the kernel to make TimeSys Linux/RT preemptable. Selected customers are currently getting a beta-preview of this product, which is scheduled to ship in the 4th quarter of 2000. The competition's uniprocessor preemptable platform (but still without necessary real-time capabilities) is not expected to ship before early 2001.
- TimeSys Linux/RT capabilities are not hidden or abstract; they can be explicitly visualized by the use of the TimeTrace product from TimeSys. The exact sequence of scheduling events and system calls occurring on multiple TimeSys Linux/RT targets can be viewed on a host and verified for strict correctness. In fact, code segments and system calls that take less than tens of nanoseconds can be measured _without_ adding any code to an application.
- TimeSys principals have long been active leaders in the real-time system industry, playing prominent roles in the invention of key protocols, scheduling policies, resource management techniques. They have also been long-term contributors to many standards in the domain including Real-Time Extensions to POSIX, Real-Time Java, Ada 95, Real-Time CORBA and Real-Time UML. A TimeSys co-founder was a co-lead of the group that developed the Real-Time Mach operating system, one of the very first general-purpose hard-real-time operating systems. In fact, TimeSys Linux/RT includes many of the innovations from Real-Time Mach.
- More innovations in TimeSys Linux/RT and tool support are available. Such tool support is necessary to significantly reduce time-to-market, a key concern for customers.It is unfortunate that one competitor is trying to confuse a growing market by making false claims. Embedded real-time extensions to Linux make it an attractive platform for developers tied to legacy platforms and tools, and it is in the best interest of embedded Linux users to know exactly what their options are so that they can make the right decision. Doing right by embedded Linux users is necessary to keep this space growing at its current high rate.
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