mmap

来源： https://stackoverflow.com/questions/55768549/in-malloc-why-use-brk-at-all-why-not-just-use-mmap

来源： https://stackoverflow.com/questions/29883547/mmap2-function-write-in-asm-call-in-c

来源： https://stackoverflow.com/questions/60079327/how-to-mmap-a-large-file-without-risking-the-oom-killer

问题 I'm writing a userspace driver for accessing FPGA registers in Python 3.5 that mmap s the FPGA's PCI address space, obtains a memoryview to provide direct access to the memory-mapped register space, and then uses struct.pack_into("<I", ...) to write a 32-bit value into the selected 32-bit aligned address. def write_u32(address, data): assert address % 4 == 0, "Address must be 32-bit aligned" path = path.lib.Path("/dev/uio0") file_size = path.stat().st_size with path.open(mode='w+b') as f: mv

问题 I'm writing a userspace driver for accessing FPGA registers in Python 3.5 that mmap s the FPGA's PCI address space, obtains a memoryview to provide direct access to the memory-mapped register space, and then uses struct.pack_into("<I", ...) to write a 32-bit value into the selected 32-bit aligned address. def write_u32(address, data): assert address % 4 == 0, "Address must be 32-bit aligned" path = path.lib.Path("/dev/uio0") file_size = path.stat().st_size with path.open(mode='w+b') as f: mv

问题 I'm writing a userspace driver for accessing FPGA registers in Python 3.5 that mmap s the FPGA's PCI address space, obtains a memoryview to provide direct access to the memory-mapped register space, and then uses struct.pack_into("<I", ...) to write a 32-bit value into the selected 32-bit aligned address. def write_u32(address, data): assert address % 4 == 0, "Address must be 32-bit aligned" path = path.lib.Path("/dev/uio0") file_size = path.stat().st_size with path.open(mode='w+b') as f: mv

问题 I'm writing a userspace driver for accessing FPGA registers in Python 3.5 that mmap s the FPGA's PCI address space, obtains a memoryview to provide direct access to the memory-mapped register space, and then uses struct.pack_into("<I", ...) to write a 32-bit value into the selected 32-bit aligned address. def write_u32(address, data): assert address % 4 == 0, "Address must be 32-bit aligned" path = path.lib.Path("/dev/uio0") file_size = path.stat().st_size with path.open(mode='w+b') as f: mv

问题 Is there a method to save a numpy memmap array into a .npy file? Apparently, there is a method to load such an array from a .npy file as follows data = numpy.load("input.npy", mmap_mode='r') but flushing the file is not equivalent to storing it in a .npy format. If flushing is the only way to go then is there a way to infer the shape of the stored array? I would prefer to have dynamic shape which is automatically stored and retrieved (possibly as memmap again) in another script. I have

问题 I'm writing some software to deal with pretty critical data, and need to know what exactly I need to do to achieve durability. Everywhere I look is contradictory information, so I'd appreciate any insight. There are three ways I write to disk. Using O_DIRECT | O_DSYNC, and pread'ing and then pwrite'ing 512 byte - 16 MB blocks. Using O_DIRECT, pread'ing and then pwrite'ing 512 byte blocks, and calling fdatasync as regularly as necessary. Using a memory mapped file, which I call msync(..., MS

问题 I've been looking at the different flags for the mmap function, namely MAP_FIXED, MAP_SHARED, MAP_PRIVATE. Can someone explain to me the purpose of MAP_FIXED? There's no guarantee that the address space will be used in the first place. 回答1: MAP_FIXED is dup2 for memory mappings, and it's useful in exactly the same situations where dup2 is useful for file descriptors: when you want to perform a replace operation that atomically reassigns a resource identifier (memory range in the case of MAP