ia64/linux-2.6.18-xen.hg

view arch/mips/tx4938/Kconfig @ 897:329ea0ccb344

balloon: try harder to balloon up under memory pressure.

Currently if the balloon driver is unable to increase the guest's
reservation it assumes the failure was due to reaching its full
allocation, gives up on the ballooning operation and records the limit
it reached as the "hard limit". The driver will not try again until
the target is set again (even to the same value).

However it is possible that ballooning has in fact failed due to
memory pressure in the host and therefore it is desirable to keep
attempting to reach the target in case memory becomes available. The
most likely scenario is that some guests are ballooning down while
others are ballooning up and therefore there is temporary memory
pressure while things stabilise. You would not expect a well behaved
toolstack to ask a domain to balloon to more than its allocation nor
would you expect it to deliberately over-commit memory by setting
balloon targets which exceed the total host memory.

This patch drops the concept of a hard limit and causes the balloon
driver to retry increasing the reservation on a timer in the same
manner as when decreasing the reservation.

Also if we partially succeed in increasing the reservation
(i.e. receive less pages than we asked for) then we may as well keep
those pages rather than returning them to Xen.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Fri Jun 05 14:01:20 2009 +0100 (2009-06-05)
parents 831230e53067
children
line source
1 if TOSHIBA_RBTX4938
3 comment "Multiplex Pin Select"
4 choice
5 prompt "PIO[58:61]"
6 default TOSHIBA_RBTX4938_MPLEX_PIO58_61
8 config TOSHIBA_RBTX4938_MPLEX_PIO58_61
9 bool "PIO"
10 config TOSHIBA_RBTX4938_MPLEX_NAND
11 bool "NAND"
12 config TOSHIBA_RBTX4938_MPLEX_ATA
13 bool "ATA"
15 endchoice
17 config TX4938_NAND_BOOT
18 depends on EXPERIMENTAL && TOSHIBA_RBTX4938_MPLEX_NAND
19 bool "NAND Boot Support (EXPERIMENTAL)"
20 help
21 This is only for Toshiba RBTX4938 reference board, which has NAND IPL.
22 Select this option if you need to use NAND boot.
24 endif