wunder@hpcea.HP (Walter R. Underwood) (07/02/86)
HP-UX is a real-time Unix. I am not a real-time wizard, but people here have a lot of experience with real-time OS's, and put a lot of careful effort into this kernel. There was a paper on the subject at the Atlanta Usenix, "Decreasing Realtime Process Dispatch Latency through Kernel Preemption." The work was done for the Spectrum kernel (HP9000 Model 840, a hot machine), and I don't know if it has made it to the 68000 kernel. The 68000 machines (HP9000 Model 320) do have real-time stuff, I just don't know whether they have kernel preemption. Walter Underwood Not an official spokesman for Hewlett-Packard
rml@hpfcdc.HP.COM (Bob Lenk) (07/08/86)
> The work > was done for the Spectrum kernel (HP9000 Model 840, a hot machine), and > I don't know if it has made it to the 68000 kernel. The 68000 machines > (HP9000 Model 320) do have real-time stuff, I just don't know whether > they have kernel preemption. I'll try to fill in enough details on the product line to clarify this, without turning this into an ad. The real-time work in HP-UX has two sides. One side is kernel preemption, as described in the Usenix paper. The other side is feature set, including SysV, 4.2BSD, and some of HP's own features (eg. non-degrading process priorities, file preallocation). The model 840 is the only machine with the whole nine yards. The series 300 and series 200 (68K family, some 10's and some 20's) machines have the full feature set (or nearly the full feature set, depending on whether a couple of features are classified as real-time), but no kernel preemption. The HP9000 series 500 (proprietary architecture) has most of the features and a preemptable kernel which has not been as well tuned for real-time as the 840, and thus does not give as predictable response in all cases. The Integral Personal computer (68000 based) has most of the features, but no kernel preemption. Bob Lenk {ihnp4, hplabs}!hpfcla!rml Standard disclaimer: The above statements are made my me personally, and do not represent any official position of my employer.
bjb@mitisft.UUCP (07/10/86)
The Mightyframe by Convergent Technologies offers several features that make many real time applications doable. The most important features are: Preemptive scheduling A correctly implemented plock() call Other interesting V.2.0.2 extensions include A bitmapped file system A method of bypassing the buffer pool for "regular" file i/o While these features alone do not make a "real time OS", they actually seem to satisfy many "real time needs." Bruce Beare Manager of Mightyframe SW Development (certainly affiliated with Convergent Technologies) ..!pyramid!ctnews!dv1!bjb (408) 435-3793