After doing some reading, into old linux kernel documentation, and Solaris Internals documentation, these are my new-found understanding, please criticize if u want: a. Firstly, as shown in the different slab types in /proc/slabinfo, anonymous pages are mainly for userspace memory, whereas the non-anonymous memory slabs are reserved for the different kernel memory types. Correct? And that is why it can be swapped out, as kernel memory pages are not swappable. b. Next is the virtual memory space of the process - it is either file-backed (file in this context is not swapfile, and it can be anything that has an inode), or anonymous memory (which is swap-backed). Anonymous are for example like copy-on-write memory, stack, heap, etc. File-backed are basically linked to the inode in the filesystem. Usage of file-backed memory are like the read-only segment mappings for ELF image - the ELF's text segment are readonly, and so no need to map to swap. (Question: what if the swapfile is a ext2 file, not a partition, then can u call that anonymous memory? Or is it not worth arguing, only for academic purposes.) The intermediary that linked these two types of memory and the physical storage is the pagecache (for inode) and swapcache (for anonymous page). c. "Anonymous pages are always created in response to a request for memory from a single process (eg, using malloc()); as a result, they are never shared at creation time." This is quoted from lwn.net, but what if the memory is allocated with MAP_SHARED? There are a lot more information in these area here: http://www.opensolaris.org/os/community/edu/curriculum_development/ ==> surprisingly, a lot of the stuff here mapped to what that has been said in lwn.net, except that lwn.net is much more dispersed and difficult to find. (just switch terms and vnode and inode will help). http://lwn.net/Articles/75198/ http://linux-mm.org/PageReplacementDesign -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
