This article is from a FAQ concerning SCO operating systems. While some of the information may be applicable to any OS, or any Unix or Linux OS, it may be specific to SCO Xenix, Open This is an old article about SCO Unix and is only left here for historical purposes. There is lots of Linux, Mac OS X and general Unix info elsewhere on this site: Search this site is the best way to find anything.
NCALL controls the size of the kernel callout table. The kernel has the ability to schedule some action at a given real time; this is often used by device drivers and by the nap(S) system call. The size of this table is set by NCALL. If the system message "timeout table overflow" appears on your console, NCALL should be increased.
Increasing NCALL is not expensive in terms of memory or CPU overhead, as the structure is small (16 bytes per entry) and stored sorted, so it is best to be generous with these entries.Linux: you can find a list of kernel parameters in /usr/src/linux-*/Documentation/kernel-parameters.txt on recent systems. Sometimes you even get a little bit of explanation. The versions I have don't list NCALL.
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On two occasions, I have been asked [by members of Parliament], "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?"...I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. (Charles Babbage)