CARS@CUTHRY.BITNET (04/21/87)
Does any of the VMS documentation mention what the process state =
RWMPB shown by $ SHOW SYSTEM represents - it's not listed in
the MONITOR utility or GETJPI system service list of states.
Does anyone know off hand what it means? Thanks,
Claire Russell
cars@cuthry"MCCORE::BOLTHOUSE@ti-eg.CSNET" (04/22/87)
Resource Wait Modified Page writer Busy: This happens when the SWAPPER is trying to flush the modified list to the [pagefile, swapfile, section file ... depending upon what kind of page it is ... the swapfile is used if your pagefile(s) are too full]. If you have a program [say a Monte Carlo simulation, or a FORTRAN programmer accessing 1000 * 1000 complex * 16 arrays in the wrong order :-( ] with a working set small enough to cause paging, your modified list will quickly reach MPW_HILIMIT/MPW_WAITLIMIT. When this happens, the SWAPPER must recover enough pages to allow use of the modified list again. It does this by writing pages. Of course, this takes a while (I/O is expensive...). If a second process produces a modified page during this time, it can't be added to the already-bloated modified list, so it goes into a resource wait: RWMPB. It is especially nasty when you have a badly-behaved program on the secondary processor, and the SWAPPER madly trying to write out pages on the primary. Mr. Rogers asks, "Can *you* say 'gee, my 8800/83xx appears to be hung'"? We have had overly-zealous system managers perform @CRASH from the console because the system got *so* badly glutted with modified pages it hung for several seconds. Users then thought their processes were hung, so they did the 'logical' thing: log in again. Of course, with many users trying this simultaneously, we exceeded BALSETCNT, which made the SWAPPER work harder, which made it hang *even more*, and ... you get the picture. Several processes in RWMPB generally means your system has a problem. Usually, this can be traced to a badly-behaved application or poorly-balanced page caches (i.e., your modified list needs to be bigger!). david l. bolthouse texas instruments defense electronics information systems VAX system support ma bell: 214.952-2059 arpa: bolthouse%mccore@ti-eg.csnet csnet: bolthouse%mccore@ti-eg disclaimer: you know by now that my employer thinks i'm silly.