Sure, I forgot what you said; precisely the mechanism allows to use lots of linear space without necessarily allocating physical memory (demand paging and the like). What about the rest of what I said? Is it correct or is there something wrong about it? Thanks. On 5/13/13, Valdis.Kletnieks@xxxxxx <Valdis.Kletnieks@xxxxxx> wrote: > On Mon, 13 May 2013 14:11:22 -0500, Sergio Andr said: > >> 2. When user applications allocates memory, the kernel must allocate >> virtual memory and physical memory, right? > > Wrong. If userspace allocates (say) 15M of memory, the kernel has every > right > to overcommit and not actually allocate either physical memory or backing > page > space for all 15M. It instead maps it as a non-existent virtual address, > and > if/when the application actually touches the page, it generates a page > fault, > and *then* the kernel does the allocating of physical memory and maybe swap > space. > > _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
