lkml.org 
[lkml]   [2012]   [Sep]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [PATCH] Add a page cache-backed balloon device driver.
    Date
    Mike Waychison <mikew@google.com> writes:
    > On Mon, Sep 10, 2012 at 3:59 PM, Michael S. Tsirkin <mst@redhat.com> wrote:
    >> On Mon, Sep 10, 2012 at 01:37:06PM -0400, Mike Waychison wrote:
    >>> On Mon, Sep 10, 2012 at 5:05 AM, Michael S. Tsirkin <mst@redhat.com> wrote:
    >>> > On Tue, Jun 26, 2012 at 01:32:58PM -0700, Frank Swiderski wrote:
    >>> >> This implementation of a virtio balloon driver uses the page cache to
    >>> >> "store" pages that have been released to the host. The communication
    >>> >> (outside of target counts) is one way--the guest notifies the host when
    >>> >> it adds a page to the page cache, allowing the host to madvise(2) with
    >>> >> MADV_DONTNEED. Reclaim in the guest is therefore automatic and implicit
    >>> >> (via the regular page reclaim). This means that inflating the balloon
    >>> >> is similar to the existing balloon mechanism, but the deflate is
    >>> >> different--it re-uses existing Linux kernel functionality to
    >>> >> automatically reclaim.
    >>> >>
    >>> >> Signed-off-by: Frank Swiderski <fes@google.com>
    >>>
    >>> Hi Michael,
    >>>
    >>> I'm very sorry that Frank and I have been silent on these threads.
    >>> I've been out of the office and Frank has been been swamped :)
    >>>
    >>> I'll take a stab at answering some of your questions below, and
    >>> hopefully we can end up on the same page.

    Hi Mike, Frank, Michael,

    Thanks for the explanation and discussion. I like that this
    implementation is more dynamic: the guest can use more pages for a while
    (and the balloon kthread will furiously start trying to grab more pages
    to give back). This part is a completely reasonable implementation, and
    more sophisticated that what we have.

    It doesn't *quite* meet the spec, because we don't notify the host when
    we pull a page from the balloon, but I think that is quite possible. If
    this is a performance waster, we should add a "SILENT_DEFLATE" feature
    to tell the driver that it doesn't need to, though we should stll
    support the !SILENT_DEFLATE case.

    And Michael: thanks again for doing the heavy lifting on this!

    Cheers,
    Rusty.


    \
     
     \ /
      Last update: 2012-09-12 09:01    [W:2.405 / U:1.092 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site