sasaki@HARVARD.HARVARD.EDU (Marty Sasaki) (09/05/85)
There is more to tuning VMS than just the working set stuff (limits, quotas and extents). Look in the "Guide to VAX/VMS Performance" for a complete discussion. In general, I make the limits and quotas small, and make the extent fairly large. I also make the modified list and the free list limits large. I set PFRATL to zero and PFRATH to something small, maybe 2 or 3. My rationale for this is the following: My machines are all at 8 meg, so I usually have more than enough memory, i.e. working sets can be large and not present a problem. A large image that faults a lot will grow and run fairly well. By making the free list and modified list fairly large most of the page faults don't have to go to the disk. The rationale for making working set limit and quota small is that occasionally I get a lot of users on the system. When there isn't a lot of spare pages, extention doesn't take place, and since the working sets are small, I don't end up swapping, just paging. Again, by having the free and modified lists fairly large, page faults don't have to go to the disk. Obviously, your system is different. I use my system as an example of what you can try. The best way is to experiment. Remember to change a few (ideally only one) parameters at a time, and keep notes of what you are doing. Good luck. Marty Sasaki (sasaki@harvard)