view arch/mips/sgi-ip27/TODO @ 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
line source
1 1. Need to figure out why PCI writes to the IOC3 hang, and if it is okay
2 not to write to the IOC3 ever.
3 2. Need to figure out RRB allocation in bridge_startup().
4 3. Need to figure out why address swaizzling is needed in inw/outw for
5 Qlogic scsi controllers.
6 4. Need to integrate ip27-klconfig.c:find_lboard and
7 ip27-init.c:find_lbaord_real. DONE
8 5. Is it okay to set calias space on all nodes as 0, instead of 8k as
9 in irix?
10 6. Investigate why things do not work without the setup_test() call
11 being invoked on all nodes in ip27-memory.c.
12 8. Too many do_page_faults invoked - investigate.
13 9. start_thread must turn off UX64 ... and define tlb_refill_debug.
14 10. Need a bad pmd table, bad pte table. __bad_pmd_table/__bad_pagetable
15 does not agree with pgd_bad/pmd_bad.
16 11. All intrs (ip27_do_irq handlers) are targetted at cpu A on the node.
17 This might need to change later. Only the timer intr is set up to be
18 received on both Cpu A and B. (ip27_do_irq()/bridge_startup())
19 13. Cache flushing (specially the SMP version) has to be investigated.