jcallen@Encore.COM (Jerry Callen) (01/31/91)
In article <5600@auspex.auspex.com> guy@auspex.auspex.com (Guy Harris) writes: >>Incidentally, as far as I know no USG/BSD derived Unix kernel uses a >>file cache, in the sense in which OS/360 and others use to. > >What sense is that? Caching entire files? In my dozen or so years of experience with OS/360 and its mutant children (VS1, SVS, MVS, MVS/XA) I've never heard of file caching per se. What OS/360 et al DID have is caching for: - disk addresses of heavily used exectables (something called the "BLDL list") - the entire text of REALLY heavily used executables (various mechanisms) These "caches" were staticly built when the system was booted; the system administrator had to provide a list of what to cache, and which mechanism to use (in the virtual memory systems, the caches could be in fixed or pageable storage). Constructing the lists was a bit of an art, for which companies paid big bucks. For a while there was also a patch that made the BLDL list a true, self-tuning cache; MVS/XA made the patch obsolete by caching the disk address of EVERY system-wide executable (hey, memory got cheap, right?). But aside from these schemes for dealing with executables, I never heard of anything like "file caching" for OS/360. Did I miss something? -- Jerry Callen jcallen@encore.com P.S. to IBM-literates: Yes, a "patch" is a "sysmod", an "executable" is a "load module", the system is not "booted" but "IPLed", etc. Please don't flame me about terminology; flame me about something interesting. :-)