view drivers/net/ixp2000/pm3386.h @ 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 /*
2 * Helper functions for the PM3386s on the Radisys ENP2611
3 * Copyright (C) 2004, 2005 Lennert Buytenhek <buytenh@wantstofly.org>
4 * Dedicated to Marija Kulikova.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 */
12 #ifndef __PM3386_H
13 #define __PM3386_H
15 void pm3386_reset(void);
16 int pm3386_port_count(void);
17 void pm3386_init_port(int port);
18 void pm3386_get_mac(int port, u8 *mac);
19 void pm3386_set_mac(int port, u8 *mac);
20 void pm3386_get_stats(int port, struct net_device_stats *stats);
21 void pm3386_set_carrier(int port, int state);
22 int pm3386_is_link_up(int port);
23 void pm3386_enable_rx(int port);
24 void pm3386_disable_rx(int port);
25 void pm3386_enable_tx(int port);
26 void pm3386_disable_tx(int port);
29 #endif