On Fri, Apr 04, 2008 at 03:06:18PM -0700, Christoph Lameter wrote: > Adds some comments. Still objectionable is the multiple ways of > invalidating pages in #v11. Callout now has similar locking to emm.
range_begin exists because range_end is called after the page has already been freed. invalidate_page is called _before_ the page is freed but _after_ the pte has been zapped. In short when working with single pages it's a waste to block the secondary-mmu page fault, because it's zero cost to invalidate_page before put_page. Not even GRU need to do that. Instead for the multiple-pte-zapping we have to call range_end _after_ the page is already freed. This is so that there is a single range_end call for an huge amount of address space. So we need a range_begin for the subsystems not using page pinning for example. When working with single pages (try_to_unmap_one, do_wp_page) invalidate_page avoids to block the secondary mmu page fault, and it's in turn faster. Besides avoiding need of serializing the secondary mmu page fault, invalidate_page also reduces the overhead when the mmu notifiers are disarmed (i.e. kvm not running). ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Register now and save $200. Hurry, offer ends at 11:59 p.m., Monday, April 7! Use priority code J8TLD2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
