ia64/linux-2.6.18-xen.hg

view arch/alpha/kernel/err_impl.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
children
line source
1 /*
2 * linux/arch/alpha/kernel/err_impl.h
3 *
4 * Copyright (C) 2000 Jeff Wiedemeier (Compaq Computer Corporation)
5 *
6 * Contains declarations and macros to support Alpha error handling
7 * implementations.
8 */
10 union el_timestamp;
11 struct el_subpacket;
12 struct ev7_lf_subpackets;
14 struct el_subpacket_annotation {
15 struct el_subpacket_annotation *next;
16 u16 class;
17 u16 type;
18 u16 revision;
19 char *description;
20 char **annotation;
21 };
22 #define SUBPACKET_ANNOTATION(c, t, r, d, a) {NULL, (c), (t), (r), (d), (a)}
24 struct el_subpacket_handler {
25 struct el_subpacket_handler *next;
26 u16 class;
27 struct el_subpacket *(*handler)(struct el_subpacket *);
28 };
29 #define SUBPACKET_HANDLER_INIT(c, h) {NULL, (c), (h)}
31 /*
32 * Manipulate a field from a register given it's name. defines
33 * for the LSB (__S - shift count) and bitmask (__M) are required
34 *
35 * EXTRACT(u, f) - extracts the field and places it at bit position 0
36 * GEN_MASK(f) - creates an in-position mask for the field
37 */
38 #define EXTRACT(u, f) (((u) >> f##__S) & f##__M)
39 #define GEN_MASK(f) ((u64)f##__M << f##__S)
41 /*
42 * err_common.c
43 */
44 extern char *err_print_prefix;
46 extern void mchk_dump_mem(void *, size_t, char **);
47 extern void mchk_dump_logout_frame(struct el_common *);
48 extern void el_print_timestamp(union el_timestamp *);
49 extern void el_process_subpackets(struct el_subpacket *, int);
50 extern struct el_subpacket *el_process_subpacket(struct el_subpacket *);
51 extern void el_annotate_subpacket(struct el_subpacket *);
52 extern void cdl_check_console_data_log(void);
53 extern int cdl_register_subpacket_annotation(struct el_subpacket_annotation *);
54 extern int cdl_register_subpacket_handler(struct el_subpacket_handler *);
56 /*
57 * err_ev7.c
58 */
59 extern struct ev7_lf_subpackets *
60 ev7_collect_logout_frame_subpackets(struct el_subpacket *,
61 struct ev7_lf_subpackets *);
62 extern void ev7_register_error_handlers(void);
63 extern void ev7_machine_check(u64, u64, struct pt_regs *);
65 /*
66 * err_ev6.c
67 */
68 extern void ev6_register_error_handlers(void);
69 extern int ev6_process_logout_frame(struct el_common *, int);
70 extern void ev6_machine_check(u64, u64, struct pt_regs *);
72 /*
73 * err_marvel.c
74 */
75 extern void marvel_machine_check(u64, u64, struct pt_regs *);
76 extern void marvel_register_error_handlers(void);
78 /*
79 * err_titan.c
80 */
81 extern int titan_process_logout_frame(struct el_common *, int);
82 extern void titan_machine_check(u64, u64, struct pt_regs *);
83 extern void titan_register_error_handlers(void);
84 extern int privateer_process_logout_frame(struct el_common *, int);
85 extern void privateer_machine_check(u64, u64, struct pt_regs *);