xen: tmem: self-ballooning and frontswap-selfshrinking

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: Dan Magenheimer <[email protected]>

[v8: [email protected]: set default enablement depending on frontswap]
[v7: [email protected]: fix capitalization and punctuation in comments]
[v6: fix frontswap-selfshrinking initialization]
[v6: [email protected]: fix init pr_infos; add comments about swap]
[v5: [email protected]: add NULL to attr list; move inits up to decls]
[v4: [email protected]: use strict_strtoul plus a few syntactic nits]
[v3: [email protected]: fix potential divides-by-zero]
[v3: [email protected]: add many more comments, fix nits]
[v2: rebased to linux-3.0-rc1]
[v2: [email protected]: reorganize as new file (xen-selfballoon.c)]
[v2: [email protected]: proper access to vm_committed_as]
[v2: [email protected]: accounting fixes]
Cc: Jan Beulich <[email protected]>
Cc: Jeremy Fitzhardinge <[email protected]>
Cc: <[email protected]>

0 files changed, 0 insertions, 0 deletions