Hey Amar, On Thu, Aug 16, 2012 at 3:39 PM, Amarnath Revanna <amarnath.revanna@xxxxxxxxx> wrote: > Just want to add a little more for better understanding: > > When I spoke about .init section of the final kernel image, please note that > this section is going to > contain all the __init data (and functions) coming from _All_ the drivers > and modules that were included > as part of the kernel image. Hence, after initialization when we look at the > print: > > " [1.011596] Freeing unused kernel memory: 664k freed " > > we see 664k bytes being freed. > > This is a significant amount of contiguous physical memory that we can see > being released by the kernel. > > The same cannot be held true for a single loadable module which may be > releasing just a few, virtually > contiguous memory. > It's crystal clear ;-) Nice explanation. It's important to add something to clearify a bit your explanation (please correct me if I'm wrong): When Amar is talking about "virtually contiguous" kernel memory he implies that this memory is physically *dis*contiguous, i.e. based on page-entries. This is the kind of memory used for loadable modules, for instance, modules that get loaded with modprobe. On the other hand, built-in modules are compiled *inside* the kernel image (bzImage). The memory used for this image is physically contiguous: it's a big contiguous block of memory pages. Contiguous memory is important for kernel, and therefore is *very* important to spend some effort minimizing it. Regards, Ezequiel. _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
