On Tue, Nov 26, 2013 at 11:10:19AM +0800, Xiao Guangrong wrote: > On 11/25/2013 10:23 PM, Marcelo Tosatti wrote: > > On Mon, Nov 25, 2013 at 02:48:37PM +0200, Avi Kivity wrote: > >> On Mon, Nov 25, 2013 at 8:11 AM, Xiao Guangrong > >> <xiaoguangrong@xxxxxxxxxxxxxxxxxx> wrote: > >>> > >>> On Nov 23, 2013, at 3:14 AM, Marcelo Tosatti <mtosatti@xxxxxxxxxx> wrote: > >> > >> <snip complicated stuff about parent_pte> > >> > >> I'm not really following, but note that parent_pte predates EPT (and > >> the use of rcu in kvm), so all the complexity that is the result of > >> trying to pack as many list entries into a cache line can be dropped. > >> Most setups now would have exactly one list entry, which is handled > >> specially antyway. > >> > >> Alternatively, the trick of storing multiple entries in one list entry > >> can be moved to generic code, it may be useful to others. > > > > Yes, can the lockless list walking code be transformed into generic > > single-linked list walking? So the correctness can be verified > > independently, and KVM becomes a simple user of that interface. > > I'am afraid the signle-entry list is not so good as we expected. In my > experience, there're too many entries on rmap, more than 300 sometimes. > (consider a case that a lib shared by all processes). single linked list was about moving singly-linked lockless walking to generic code. http://www.spinics.net/lists/linux-usb/msg39643.html http://marc.info/?l=linux-kernel&m=103305635013575&w=3 > > The simpler version is to maintain lockless walk on depth-1 rmap entries > > (and grab the lock once depth-2 entry is found). > > I still think rmap-lockless is more graceful: soft mmu can get benefit > from it also it is promising to be used in some mmu-notify functions. :) OK. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
