On Nov 13, 2007 8:58 PM, Jacky(GuangXiang Lee) <gxli@xxxxxxxxxxx> wrote: > hi , > what is "flat" memory and "sparse" memory, and their difference? > > thanks. > Sorry, I did not read the source code, neither any paper/article on this feature yet for lack of time...just purely my guess: Normally sparse filesystem means that not every bytes need to have a physical storage available, so to store a 2TB sparse file, u may theoretically just need 1KB file, if the content of the 2TB sparse just access max 1KB of data, but u will need some metadata to map the data to its exact location within the 2TB storage space. Similarly for memory - if u maintain many different pagetable for CR3 mapping, it is possible to setup the CPU to map to a large memory, given that the physical memory is only much smaller. Contrast this to uniform flat virtual memory - whereby ONE pagetable is use to map the memory, and so every bytes that theoretically can be accessed have to have a physical byte to account for. -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
