kam@titan.tsd.arlut.utexas.edu (Katherine Minister) (06/24/89)
Hello again. We're having a very technical problem with large programs causing a pagedaemon to thrash. The system is a 4/260 running SunOS 4.0.1. The problem we have been experiencing seems to occur when a single process's virtual address space grows larger than physical memory. At this point the pagedaemon runs and reclaims most of the virtual space, then immediately needs it again and brings it back in. Thrashing occurs and CPU utilization drops to between 5-15% (with no other running processes). Both the 'vmstat' and 'ps -v' commands indicate many page faults, although with 32M of physical memory I suppose much time could be wasted just in fetching pages from the freelist. Additionally, it seems as though the resident sent of the text space is being continually reduced. Thus a fairly small program with a large data space gets its resident text space reduced to near nothing (as low as 16 pages as the process gets old) and it appears that the paging might be mainly in the text segment. We think that we can modify the pagedaemon by using adb on vmunix, but we're not sure exactly what needs to be modified or how. We think that several variables need to be changed, in particular 'min_free' , 'des_free', and perhaps another. Any information or experiences in this regard would be most appreciated. Thanks in advance :-). -- Katherine Minister Hosch: kam@titan.tsd.arlut.utexas.edu