• Dan Magenheimer's avatar
    xen: tmem: self-ballooning and frontswap-selfshrinking · a50777c7
    Dan Magenheimer authored
    This patch introduces two in-kernel drivers for Xen transcendent memory
    ("tmem") functionality that complement cleancache and frontswap.  Both
    use control theory to dynamically adjust and optimize memory utilization.
    Selfballooning controls the in-kernel Xen balloon driver, targeting a goal
    value (vm_committed_as), thus pushing less frequently used clean
    page cache pages (through the cleancache code) into Xen tmem where
    Xen can balance needs across all VMs residing on the physical machine.
    Frontswap-selfshrinking controls the number of pages in frontswap,
    driving it towards zero (effectively doing a partial swapoff) when
    in-kernel memory pressure subsides, freeing up RAM for other VMs.
    
    More detail is provided in the header comment of xen-selfballooning.c.
    Signed-off-by: default avatarDan Magenheimer <dan.magenheimer@oracle.com>
    
    [v8: konrad.wilk@oracle.com: set default enablement depending on frontswap]
    [v7: konrad.wilk@oracle.com: fix capitalization and punctuation in comments]
    [v6: fix frontswap-selfshrinking initialization]
    [v6: konrad.wilk@oracle.com: fix init pr_infos; add comments about swap]
    [v5: konrad.wilk@oracle.com: add NULL to attr list; move inits up to decls]
    [v4: dkiper@net-space.pl: use strict_strtoul plus a few syntactic nits]
    [v3: konrad.wilk@oracle.com: fix potential divides-by-zero]
    [v3: konrad.wilk@oracle.com: add many more comments, fix nits]
    [v2: rebased to linux-3.0-rc1]
    [v2: Ian.Campbell@citrix.com: reorganize as new file (xen-selfballoon.c)]
    [v2: dkiper@net-space.pl: proper access to vm_committed_as]
    [v2: dkiper@net-space.pl: accounting fixes]
    Cc: Jan Beulich <JBeulich@novell.com>
    Cc: Jeremy Fitzhardinge <jeremy@goop.org>
    Cc: <xen-devel@lists.xensource.com>
    a50777c7
xen-selfballoon.c 15 KB