ia64/linux-2.6.18-xen.hg

view scripts/kconfig/util.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 * Copyright (C) 2002-2005 Roman Zippel <zippel@linux-m68k.org>
3 * Copyright (C) 2002-2005 Sam Ravnborg <sam@ravnborg.org>
4 *
5 * Released under the terms of the GNU GPL v2.0.
6 */
8 #include <string.h>
9 #include "lkc.h"
11 /* file already present in list? If not add it */
12 struct file *file_lookup(const char *name)
13 {
14 struct file *file;
16 for (file = file_list; file; file = file->next) {
17 if (!strcmp(name, file->name))
18 return file;
19 }
21 file = malloc(sizeof(*file));
22 memset(file, 0, sizeof(*file));
23 file->name = strdup(name);
24 file->next = file_list;
25 file_list = file;
26 return file;
27 }
29 /* write a dependency file as used by kbuild to track dependencies */
30 int file_write_dep(const char *name)
31 {
32 struct file *file;
33 FILE *out;
35 if (!name)
36 name = ".kconfig.d";
37 out = fopen("..config.tmp", "w");
38 if (!out)
39 return 1;
40 fprintf(out, "deps_config := \\\n");
41 for (file = file_list; file; file = file->next) {
42 if (file->next)
43 fprintf(out, "\t%s \\\n", file->name);
44 else
45 fprintf(out, "\t%s\n", file->name);
46 }
47 fprintf(out, "\ninclude/config/auto.conf: \\\n"
48 "\t$(deps_config)\n\n"
49 "$(deps_config): ;\n");
50 fclose(out);
51 rename("..config.tmp", name);
52 return 0;
53 }
56 /* Allocate initial growable sting */
57 struct gstr str_new(void)
58 {
59 struct gstr gs;
60 gs.s = malloc(sizeof(char) * 64);
61 gs.len = 16;
62 strcpy(gs.s, "\0");
63 return gs;
64 }
66 /* Allocate and assign growable string */
67 struct gstr str_assign(const char *s)
68 {
69 struct gstr gs;
70 gs.s = strdup(s);
71 gs.len = strlen(s) + 1;
72 return gs;
73 }
75 /* Free storage for growable string */
76 void str_free(struct gstr *gs)
77 {
78 if (gs->s)
79 free(gs->s);
80 gs->s = NULL;
81 gs->len = 0;
82 }
84 /* Append to growable string */
85 void str_append(struct gstr *gs, const char *s)
86 {
87 size_t l = strlen(gs->s) + strlen(s) + 1;
88 if (l > gs->len) {
89 gs->s = realloc(gs->s, l);
90 gs->len = l;
91 }
92 strcat(gs->s, s);
93 }
95 /* Append printf formatted string to growable string */
96 void str_printf(struct gstr *gs, const char *fmt, ...)
97 {
98 va_list ap;
99 char s[10000]; /* big enough... */
100 va_start(ap, fmt);
101 vsnprintf(s, sizeof(s), fmt, ap);
102 str_append(gs, s);
103 va_end(ap);
104 }
106 /* Retrieve value of growable string */
107 const char *str_get(struct gstr *gs)
108 {
109 return gs->s;
110 }