ia64/linux-2.6.18-xen.hg

view arch/mips/arc/tree.c @ 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 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * PROM component device tree code.
7 *
8 * Copyright (C) 1996 David S. Miller (dm@engr.sgi.com)
9 * Copyright (C) 1999 Ralf Baechle (ralf@gnu.org)
10 * Copyright (C) 1999 Silicon Graphics, Inc.
11 */
12 #include <linux/init.h>
13 #include <asm/arc/types.h>
14 #include <asm/sgialib.h>
16 #undef DEBUG_PROM_TREE
18 pcomponent * __init
19 ArcGetPeer(pcomponent *Current)
20 {
21 if (Current == PROM_NULL_COMPONENT)
22 return PROM_NULL_COMPONENT;
24 return (pcomponent *) ARC_CALL1(next_component, Current);
25 }
27 pcomponent * __init
28 ArcGetChild(pcomponent *Current)
29 {
30 return (pcomponent *) ARC_CALL1(child_component, Current);
31 }
33 pcomponent * __init
34 ArcGetParent(pcomponent *Current)
35 {
36 if (Current == PROM_NULL_COMPONENT)
37 return PROM_NULL_COMPONENT;
39 return (pcomponent *) ARC_CALL1(parent_component, Current);
40 }
42 LONG __init
43 ArcGetConfigurationData(VOID *Buffer, pcomponent *Current)
44 {
45 return ARC_CALL2(component_data, Buffer, Current);
46 }
48 pcomponent * __init
49 ArcAddChild(pcomponent *Current, pcomponent *Template, VOID *ConfigurationData)
50 {
51 return (pcomponent *)
52 ARC_CALL3(child_add, Current, Template, ConfigurationData);
53 }
55 LONG __init
56 ArcDeleteComponent(pcomponent *ComponentToDelete)
57 {
58 return ARC_CALL1(comp_del, ComponentToDelete);
59 }
61 pcomponent * __init
62 ArcGetComponent(CHAR *Path)
63 {
64 return (pcomponent *)ARC_CALL1(component_by_path, Path);
65 }
67 #ifdef DEBUG_PROM_TREE
69 static char *classes[] = {
70 "system", "processor", "cache", "adapter", "controller", "peripheral",
71 "memory"
72 };
74 static char *types[] = {
75 "arc", "cpu", "fpu", "picache", "pdcache", "sicache", "sdcache",
76 "sccache", "memdev", "eisa adapter", "tc adapter", "scsi adapter",
77 "dti adapter", "multi-func adapter", "disk controller",
78 "tp controller", "cdrom controller", "worm controller",
79 "serial controller", "net controller", "display controller",
80 "parallel controller", "pointer controller", "keyboard controller",
81 "audio controller", "misc controller", "disk peripheral",
82 "floppy peripheral", "tp peripheral", "modem peripheral",
83 "monitor peripheral", "printer peripheral", "pointer peripheral",
84 "keyboard peripheral", "terminal peripheral", "line peripheral",
85 "net peripheral", "misc peripheral", "anonymous"
86 };
88 static char *iflags[] = {
89 "bogus", "read only", "removable", "console in", "console out",
90 "input", "output"
91 };
93 static void __init
94 dump_component(pcomponent *p)
95 {
96 prom_printf("[%p]:class<%s>type<%s>flags<%s>ver<%d>rev<%d>",
97 p, classes[p->class], types[p->type],
98 iflags[p->iflags], p->vers, p->rev);
99 prom_printf("key<%08lx>\n\tamask<%08lx>cdsize<%d>ilen<%d>iname<%s>\n",
100 p->key, p->amask, (int)p->cdsize, (int)p->ilen, p->iname);
101 }
103 static void __init
104 traverse(pcomponent *p, int op)
105 {
106 dump_component(p);
107 if(ArcGetChild(p))
108 traverse(ArcGetChild(p), 1);
109 if(ArcGetPeer(p) && op)
110 traverse(ArcGetPeer(p), 1);
111 }
113 void __init
114 prom_testtree(void)
115 {
116 pcomponent *p;
118 p = ArcGetChild(PROM_NULL_COMPONENT);
119 dump_component(p);
120 p = ArcGetChild(p);
121 while(p) {
122 dump_component(p);
123 p = ArcGetPeer(p);
124 }
125 }
127 #endif /* DEBUG_PROM_TREE */