V Storage Manager Shahram Ghandeharizadeh Computer Science Department University of Southern California Traces Make sure your persistent BDB is configured with 256 MB of memory With a trace say 21 use its 21Objs Save to create and populate your persistent database Subsequently use its Trace21 1KGet to debug your software Start with 1 thread and expand to 2 3 and 4 Try to make your software as efficient as possible If it is too slow maybe because of low byte hit rates then you may not be able to run Trace21 1MGet Questions Questions Will there be another release of the workload generator before Friday I do not anticipate one unless there is a bug report Is there an obvious item missing from the current workload generator Mandatory Invocation of the method to report cache and byte hit rates Optional Dump the content of the cache to analyze the behavior of your cache replacement technique Hints BDB Disk is a full fledged storage manager with a buffer pool locking crash recovery index structures Configure its buffer pool size to be 256 MB V Functionalities Cache Replacement BDB Disk BDB Mem Hints Your implementation may need to keep track of different counters Example count the number of requests issued and the number of requests serviced from the main memory instance of BDB to compute the cache hit rate How to do this with multiple worker threads Hints Your implementation may need to keep track of different counters Example count the number of requests issued to compute the cache hit rate How to do this with multiple worker threads The interlocked function provides a mechanism for synchronizing access to a variable that is shared by multiple threads You may define a long variable and use InterlockedIncrement long cntr InterlockedIncrement cntr Make sure to include windows h Hints To compute byte hit rates you need to maintain two counters and increment them by the size of the referenced object Use InterlockedExchangeAdd function to perform an atomic addition of two 32 bit values Example a a b InterlockedExchangeAdd a b Other Interlocked methods might be useful to you such as InterlockedExchangePointer Hints With invocation of methods local variables are pushed on the stack of a thread 4 different threads invoking a method will have 4 different sets of mutually exclusive local variables as declared by that method Foo Char res 200 Int cntr A global variable is not part of the stack and must be protected when multiple threads are manipulating it How Hints With invocation of methods local variables are pushed on the stack of a thread 4 different threads invoking a method will have 4 different sets of mutually exclusive local variables as declared by that method Foo Char res 200 Int cntr A global variable is not part of the stack and must be protected when multiple threads are manipulating it How Consider making it a variable local to a method Ask Does this variable have to be global Use critical sections Manage memory Hints With invocation of methods local variables are pushed on the stack of a thread 4 different threads invoking a method will have 4 different sets of mutually exclusive local variables as declared by that method Foo Char res 200 Int cntr Similarly memory allocated from the heap new malloc is not a part of the stack and must be managed No memory leaks Hints Consider an admission control technique Without admission control Everytime an object is referenced and it is not in memory then you place it in memory With admission control Every time a disk resident object is referenced compare its Q value with the minimum Q value to see if it should be admitted into memory
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