Posted on 04/25/2005 7:47:12 AM PDT by 1FASTGLOCK45
These days, most of the kernel is in C and the device drivers I write are in C. I was skeptical at first(surprised look)
I was skeptical with good reason. I once did an interrupt latency survey on a variety of machines, which involved installing a high-resolution real-time clock that could be configured to generate an interrupt and time the response of the operating system to that interrupt. I tested Ultrix/MIPS, OSF1/Alpha, VMS/Alpha, and VMS/VAX using it.
Ultrix and OSF/1 were horrible. Latency was all over the place. In versions of OSF/1 prior to V1.3, there was a nasty bug when a process was torn down that caused an interrupt latency glitch related to the size of the process. If a large enough process ended, an 8-byte hardware FIFO was not sufficient to prevent loss of data for a serial port running at 300(!) baud. Ultrix had a similar problem, but not as large.
VMS interrupt latency was consistently very low regardless of the workload of the machine. Oddly, interrupt latency on a VAXstation 4000/60 (12-ish MIPs machine) was noticeably better than latency on a VAXstation 4000/90 (50-ish MIPs machine).
The last time I looked at this issue, the latency of VMS had become more variable. And more of the kernel was being done in C. Coincidence?
I haven't looked at this issue in many years, so I don't know if the VMS guys have been able to climb back on top of the interrupt latency. And I'm not looking forward to latency issues on Itanium, what with its huge processor context that needs to be saved on interrupt...
You'll take a third-party out-of-state hot check, right?
I only accept third-party out-of-state hot chicks.
Oh wait, you said "check".
LOL! I had forgotten about the Alpha.
I found a ref to what I was talking about. Windows 2000 Advanced Server "Limited Edition" (shoulda dropped that part)came out in 2001 for the Itanium.
Don't know if anything ever ran on it.
http://www.entmag.com/news/article.asp?EditorialsID=1924
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