shared-memory

问题 We have a need for multiple programs to call functions in a common library. The library functions access and update a common global memory. Each program’s function calls need to see this common global memory. That is one function call needs to see the updates of any prior function call even if called from another program. For compatibility reasons we have several design constraints on how the functions exposed by the shared library must operate: Any data items (both standard data types and

问题 We have a need for multiple programs to call functions in a common library. The library functions access and update a common global memory. Each program’s function calls need to see this common global memory. That is one function call needs to see the updates of any prior function call even if called from another program. For compatibility reasons we have several design constraints on how the functions exposed by the shared library must operate: Any data items (both standard data types and

问题 Boost provides a sample atomically reference counted shared pointer Here is the relevant code snippet and the explanation for the various orderings used: class X { public: typedef boost::intrusive_ptr<X> pointer; X() : refcount_(0) {} private: mutable boost::atomic<int> refcount_; friend void intrusive_ptr_add_ref(const X * x) { x->refcount_.fetch_add(1, boost::memory_order_relaxed); } friend void intrusive_ptr_release(const X * x) { if (x->refcount_.fetch_sub(1, boost::memory_order_release)

问题 Boost provides a sample atomically reference counted shared pointer Here is the relevant code snippet and the explanation for the various orderings used: class X { public: typedef boost::intrusive_ptr<X> pointer; X() : refcount_(0) {} private: mutable boost::atomic<int> refcount_; friend void intrusive_ptr_add_ref(const X * x) { x->refcount_.fetch_add(1, boost::memory_order_relaxed); } friend void intrusive_ptr_release(const X * x) { if (x->refcount_.fetch_sub(1, boost::memory_order_release)

问题 When using shared memory, why should we care about creating a key key_t ftok(const char *path, int id); in the following bit of code? key_t key; int shmid; key = ftok("/home/beej/somefile3", 'R'); shmid = shmget(key, 1024, 0644 | IPC_CREAT); From what I've come to understand, what is needed to access a given shared memory is the shmid , not the key. Or am I wrong? If what we need is the shmid , what is the point in not just creating a random key every time? Edit @Beej's Guide to Unix IPC one

问题 Can someone explain why ashmem was created? I'm browsing through mm/ashmem.c right now. As near as I can tell, the kernel is thinking of ashmem as file-backed memory that can be mmap'd. But then, why go to the trouble of implementing ashmem? It seems like the same functionality could be achieved by mounting a RAM fs and then using filemap/mmap to share memory. I'm sure that ashmem can do more fancy stuff -- from looking at the code, it seems to have something to do with pinning/unpinning

问题 I'm looking for a program to view and browse the (local) shared memory in Windows x32/x64. I know this exists because I've seen it in action before. For some reason Google and MSDN fail me on this one. 回答1: I think Accesschk can do this. From the commandline: accesschk.exe -osv > objects.txt Search for: "Type: Section" 来源： https://stackoverflow.com/questions/465378/program-to-view-shared-memory-in-windows

问题 I am aware of several questions and answers on this topic, but haven't found a satisfactory answer to this particular problem: What is the easiest way to do a simple shared-memory parallelisation of a python loop where numpy arrays are manipulated through numpy/scipy functions? I am not looking for the most efficient way, I just wanted something simple to implement that doesn't require a significant rewrite when the loop is not run in parallel. Just like OpenMP implements in lower level

问题 Can you use shared memory to communicate between php scripts and c program in windows? The c program runs all the time and uses memory mapped files ie: handle1 = CreateFileMapping( (HANDLE)0xFFFFFFFF, NULL, PAGE_READWRITE, 0, sizeof(byte)*BUFFER_SIZE, "my_foo" ); hView = (LPINT) MapViewOfFile(handle1, FILE_MAP_ALL_ACCESS, 0, 0, 0); For the PHP scripts can I just use the below code to open the memory mapped file created by the c program? $shmkey = @shmop_open(ftok("my_foo", 'R'), "a", 0644,

问题 I want to have a shared memory block (an ashmem region) that's mapped and accessed from native code. I also want this block to be used by several applications. I also want it to work on SDK level 7 (Android 2.1) There are two routes. I can create an ashmem region in native code; but then the question is - how do I pass an integer file descriptor to another process? You can marshal FileDescriptor objects via a Parcel , but there's no way to construct one around a raw FD. There's also