We can use the function ios::rdbuf() to perform below two operations. If needed to reset the stream buffer of A to its previous stream buffer.Set the stream buffer of A to the stream buffer of B.
Get the stream buffer of A and store it somewhere.A embodiment of a memory device includes nonvolatile memory a memory controller and address indirection logic to provide address indirection for the nonvolatile memory, of the address indirection logic to maintain an address indirection table (AIT) in the nonvolatile. Thus, to redirect a Stream A to Stream B we need to do:- Embodiments are generally directed to accelerated address indirection table lookup for wear-leveled non-volatile memory. Similarly, output operations are first performed on the buffer, and then the buffer is flushed (written to the physical device) when needed.Ĭ++ allows us to set the stream buffer for any stream, So the task of redirecting the stream simply reduces to changing the stream buffer associated with the stream. When we read data from a stream, we don’t read it directly from the source, but instead, we read it from the buffer which is linked to the source. Simply put, streambuf object is the buffer for the stream. Thus, filestream and IO stream objects behave similarly.Īll stream objects also have an associated data member of class streambuf. iostream : Can be used for both input and output operationsĪll these classes, as well as file stream classes, derived from the classes: ios and streambuf.ostream : These objects can only be used for output operations.istream : Stream object of this type can only perform input operations from the stream While the binary tree structure was great for sequential IO performance and for keeping DRAM sizes low, it wasn't good for lowering random IO latency.ISRO CS Syllabus for Scientist/Engineer Exam.ISRO CS Original Papers and Official Keys.GATE CS Original Papers and Official Keys.However: The small performance drop must be weighed against the benefits of virtual memory, which are too numerous to list here. Perhaps you can sabotage the OS by allocating 4k chunks from mmap, in which case the TLB misses might be felt with only a few megs of working set, depending on your processor. If your operating system allows "big pages", the TLB might be able to cover a very large address space indeed. Above the size of available swap space and RAM, the application will be terminated by the OS.Above the size of available RAM, performance will drop due to swapping.(This might happen before or after you run out of L2 cache space, depending on a number of factors.) Above the size of the memory addressed by the TLB, performance will drop due to TLB misses.Above the L2 cache size, performance will drop to RAM latency.Above the L1 cache size, performance will drop due to L2 cache latency.Use a command line parameter to change the size. Give your test program a big chunk of memory and start randomly reading and writing locations in memory. You can see the effect of this in action by writing a test program. If your process accesses a page without a TLB entry, then the CPU must make an additional memory access to fetch the page table entry for that page. Parts of the page table will be cached in the translation lookaside buffer, accessing pages with entries in the buffer incur no additional penalty. While your process is running, the page table does not change very often. However, the cost of the check is very small. It's not just for pointer indirection, but any memory access (other than, say, DMA). Yes, you are paying the price for that extra check.