lkml.org 
[lkml]   [2013]   [Nov]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v3 07/15] KVM: MMU: introduce nulls desc
    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@linux.vnet.ibm.com> wrote:
    > >>>
    > >>> On Nov 23, 2013, at 3:14 AM, Marcelo Tosatti <mtosatti@redhat.com> 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.



    \
     
     \ /
      Last update: 2013-11-27 00:21    [W:2.265 / U:0.020 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site