dillon@CORY.BERKELEY.EDU (Matt Dillon) (08/26/87)
This can get very dangerous. For instance, if you have three 'intelligent' programs which all release memory when it gets to low, and gets memory when it gets larger, you can get into oscillations. Perry, does your low memory server (which I haven't looked at yet) handle this situation? -Matt
perry@well.UUCP (Perry S. Kivolowitz) (08/28/87)
In article <8708261849.AA12686@cory.Berkeley.EDU> dillon@CORY.BERKELEY.EDU (Matt Dillon) writes: > > This can get very dangerous. For instance, if you have three >'intelligent' programs which all release memory when it gets to low, and >gets memory when it gets larger, you can get into oscillations. > > Perry, does your low memory server (which I haven't looked at yet) >handle this situation? The Low Memory Server does not deal at all with *surplus* memory situations but only memory shortages. It will notify registered client programs that memory is short. That's all. You're completely right about the possibility of memory thrashing. Read on: To answer Dave B: FaccII does not attempt to recoup any of the memory it surrenders to the system. FaccII makes some VERY good choices about which buffers to give up which dramatically improves cache effectiveness over the original Facc especially under low memory situations. However, FaccIII will strike out in (still) another direction to improve cache effectiveness (which bears on this topic). When FaccIII gives up say 64K it will examine cache effectiveness in the short term to see if some small incremental change would improve cache effectiveness dramatically. It might elect to increase the number of buffers by one or two but no where near as much as it would have just released. Therefore, both your comment and Matt's are covered. Low Memory handling is in its embryonic stage. You can be assured that a great deal of future effort will be invested in this area for future re- leases of Facc. As it stands right now, however, the method used in FaccII is clearly superior to some used in one potential product I have heard about. Wait! I feel memory closing in all around me. Wait! Stop! Ahhhhhyyyyaaah! Perry S. Kivolowitz ASDG Incorporated - (201) 563-0529