From: Joachim Geidel <joachim.geidel(a)onlinehome.de> Date: September 26, 2009 5:10:40 PM GMT+02:00 To: Jim Guo <jimg1968(a)gmail.com>om>, vwnc <vwnc(a)cs.uiuc.edu> Subject: Re: [vwnc] any way to automaticly set memory policy? Am 26.09.09 14:40 schrieb Jim Guo: Yes, and no. :-) You can save the configuration of the Runtime Packager, including settings for MemoryPolicy parameters, for later use, such that you don't have to enter the values every time you build an image (see page 21-21 in the Application Developers Guide). But that addresses only part of the problem. MemoryPolicy does not implement the ability to adapt its parameters to its environment. But you can write a subclass of MemoryPolicy such that - it computes memoryUpperBound dynamically instead of using a constant value - it computes growthRegimeUpperBound as e.g. 90% of memoryUpperBound or whatever seems reasonable - sets defaults for other parameters to values more appropriate to larger memory sizes and the needs of your application (e.g., if your application needs large amounts of memory, it is a good idea to set preferredGrowthIncrement to a larger value than the default of 1 MB - I tend to set it to 10 MB without thinking much about it). The MemoryPolicy has several places where it can be adapted. For example, you can tweak the permitMemoryGrowth: method, the memoryMeasurementBlock or the way memoryUpperBound is determined to achieve what you want. It is relatively easy to detect how much physical memory your computer has using the appropriate operating system calls, and it's a good idea to set memoryUpperBound lower than that. VisualWorks applications can be extremely slow when parts of their memory are swapped to disk, especially when running global garbage collections. You could also implement a SubSystem which reads parameters for the MemoryPolicy from a configuration file and installs or configures the currentMemoryPolicy accordingly in its startUp method. You should also set the ObjectMemory's sizesAtStartup to larger values, especially the sizes of eden and survivor space. My rule of thumb is to set eden and survivor space to 10 times the default size, and then run the TimeProfiler on parts of the application which are likely to produce lots of temporary objects. If it shows that there are too many scavenges (garbage collection runs in NewSpace), I increase them further until scavenges don't decrease any more or time to execute the code starts increasing. You can increase the other size parameters too, in particular stack space and compiled code cache. I usually double them. If you don't use fixed space, leave its size at the default value. Increase OldSpace headroom such that it is large enough to hold the objects created after starting and initializing your application, and a bit more. That way, your application will start a bit faster, and it doesn't have to allocate more OldSpace segments during initialization. HTH, Joachim Geidel _______________________________________________ vwnc mailing list vwnc(a)cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/vwnc