ia64/linux-2.6.18-xen.hg

view drivers/acpi/utilities/utcache.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 *
3 * Module Name: utcache - local cache allocation routines
4 *
5 *****************************************************************************/
7 /*
8 * Copyright (C) 2000 - 2006, R. Byron Moore
9 * All rights reserved.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions, and the following disclaimer,
16 * without modification.
17 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
18 * substantially similar to the "NO WARRANTY" disclaimer below
19 * ("Disclaimer") and any redistribution must be conditioned upon
20 * including a substantially similar Disclaimer requirement for further
21 * binary redistribution.
22 * 3. Neither the names of the above-listed copyright holders nor the names
23 * of any contributors may be used to endorse or promote products derived
24 * from this software without specific prior written permission.
25 *
26 * Alternatively, this software may be distributed under the terms of the
27 * GNU General Public License ("GPL") version 2 as published by the Free
28 * Software Foundation.
29 *
30 * NO WARRANTY
31 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
32 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
33 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
34 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
35 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
37 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
40 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
41 * POSSIBILITY OF SUCH DAMAGES.
42 */
44 #include <acpi/acpi.h>
46 #define _COMPONENT ACPI_UTILITIES
47 ACPI_MODULE_NAME("utcache")
49 #ifdef ACPI_USE_LOCAL_CACHE
50 /*******************************************************************************
51 *
52 * FUNCTION: acpi_os_create_cache
53 *
54 * PARAMETERS: cache_name - Ascii name for the cache
55 * object_size - Size of each cached object
56 * max_depth - Maximum depth of the cache (in objects)
57 * return_cache - Where the new cache object is returned
58 *
59 * RETURN: Status
60 *
61 * DESCRIPTION: Create a cache object
62 *
63 ******************************************************************************/
64 acpi_status
65 acpi_os_create_cache(char *cache_name,
66 u16 object_size,
67 u16 max_depth, struct acpi_memory_list **return_cache)
68 {
69 struct acpi_memory_list *cache;
71 ACPI_FUNCTION_ENTRY();
73 if (!cache_name || !return_cache || (object_size < 16)) {
74 return (AE_BAD_PARAMETER);
75 }
77 /* Create the cache object */
79 cache = acpi_os_allocate(sizeof(struct acpi_memory_list));
80 if (!cache) {
81 return (AE_NO_MEMORY);
82 }
84 /* Populate the cache object and return it */
86 ACPI_MEMSET(cache, 0, sizeof(struct acpi_memory_list));
87 cache->link_offset = 8;
88 cache->list_name = cache_name;
89 cache->object_size = object_size;
90 cache->max_depth = max_depth;
92 *return_cache = cache;
93 return (AE_OK);
94 }
96 /*******************************************************************************
97 *
98 * FUNCTION: acpi_os_purge_cache
99 *
100 * PARAMETERS: Cache - Handle to cache object
101 *
102 * RETURN: Status
103 *
104 * DESCRIPTION: Free all objects within the requested cache.
105 *
106 ******************************************************************************/
108 acpi_status acpi_os_purge_cache(struct acpi_memory_list * cache)
109 {
110 char *next;
112 ACPI_FUNCTION_ENTRY();
114 if (!cache) {
115 return (AE_BAD_PARAMETER);
116 }
118 /* Walk the list of objects in this cache */
120 while (cache->list_head) {
122 /* Delete and unlink one cached state object */
124 next = *(ACPI_CAST_INDIRECT_PTR(char,
125 &(((char *)cache->
126 list_head)[cache->
127 link_offset])));
128 ACPI_FREE(cache->list_head);
130 cache->list_head = next;
131 cache->current_depth--;
132 }
134 return (AE_OK);
135 }
137 /*******************************************************************************
138 *
139 * FUNCTION: acpi_os_delete_cache
140 *
141 * PARAMETERS: Cache - Handle to cache object
142 *
143 * RETURN: Status
144 *
145 * DESCRIPTION: Free all objects within the requested cache and delete the
146 * cache object.
147 *
148 ******************************************************************************/
150 acpi_status acpi_os_delete_cache(struct acpi_memory_list * cache)
151 {
152 acpi_status status;
154 ACPI_FUNCTION_ENTRY();
156 /* Purge all objects in the cache */
158 status = acpi_os_purge_cache(cache);
159 if (ACPI_FAILURE(status)) {
160 return (status);
161 }
163 /* Now we can delete the cache object */
165 ACPI_FREE(cache);
166 return (AE_OK);
167 }
169 /*******************************************************************************
170 *
171 * FUNCTION: acpi_os_release_object
172 *
173 * PARAMETERS: Cache - Handle to cache object
174 * Object - The object to be released
175 *
176 * RETURN: None
177 *
178 * DESCRIPTION: Release an object to the specified cache. If cache is full,
179 * the object is deleted.
180 *
181 ******************************************************************************/
183 acpi_status
184 acpi_os_release_object(struct acpi_memory_list * cache, void *object)
185 {
186 acpi_status status;
188 ACPI_FUNCTION_ENTRY();
190 if (!cache || !object) {
191 return (AE_BAD_PARAMETER);
192 }
194 /* If cache is full, just free this object */
196 if (cache->current_depth >= cache->max_depth) {
197 ACPI_FREE(object);
198 ACPI_MEM_TRACKING(cache->total_freed++);
199 }
201 /* Otherwise put this object back into the cache */
203 else {
204 status = acpi_ut_acquire_mutex(ACPI_MTX_CACHES);
205 if (ACPI_FAILURE(status)) {
206 return (status);
207 }
209 /* Mark the object as cached */
211 ACPI_MEMSET(object, 0xCA, cache->object_size);
212 ACPI_SET_DESCRIPTOR_TYPE(object, ACPI_DESC_TYPE_CACHED);
214 /* Put the object at the head of the cache list */
216 *(ACPI_CAST_INDIRECT_PTR(char,
217 &(((char *)object)[cache->
218 link_offset]))) =
219 cache->list_head;
220 cache->list_head = object;
221 cache->current_depth++;
223 (void)acpi_ut_release_mutex(ACPI_MTX_CACHES);
224 }
226 return (AE_OK);
227 }
229 /*******************************************************************************
230 *
231 * FUNCTION: acpi_os_acquire_object
232 *
233 * PARAMETERS: Cache - Handle to cache object
234 *
235 * RETURN: the acquired object. NULL on error
236 *
237 * DESCRIPTION: Get an object from the specified cache. If cache is empty,
238 * the object is allocated.
239 *
240 ******************************************************************************/
242 void *acpi_os_acquire_object(struct acpi_memory_list *cache)
243 {
244 acpi_status status;
245 void *object;
247 ACPI_FUNCTION_NAME(os_acquire_object);
249 if (!cache) {
250 return (NULL);
251 }
253 status = acpi_ut_acquire_mutex(ACPI_MTX_CACHES);
254 if (ACPI_FAILURE(status)) {
255 return (NULL);
256 }
258 ACPI_MEM_TRACKING(cache->requests++);
260 /* Check the cache first */
262 if (cache->list_head) {
264 /* There is an object available, use it */
266 object = cache->list_head;
267 cache->list_head = *(ACPI_CAST_INDIRECT_PTR(char,
268 &(((char *)
269 object)[cache->
270 link_offset])));
272 cache->current_depth--;
274 ACPI_MEM_TRACKING(cache->hits++);
275 ACPI_DEBUG_PRINT((ACPI_DB_EXEC,
276 "Object %p from %s cache\n", object,
277 cache->list_name));
279 status = acpi_ut_release_mutex(ACPI_MTX_CACHES);
280 if (ACPI_FAILURE(status)) {
281 return (NULL);
282 }
284 /* Clear (zero) the previously used Object */
286 ACPI_MEMSET(object, 0, cache->object_size);
287 } else {
288 /* The cache is empty, create a new object */
290 ACPI_MEM_TRACKING(cache->total_allocated++);
292 /* Avoid deadlock with ACPI_ALLOCATE_ZEROED */
294 status = acpi_ut_release_mutex(ACPI_MTX_CACHES);
295 if (ACPI_FAILURE(status)) {
296 return (NULL);
297 }
299 object = ACPI_ALLOCATE_ZEROED(cache->object_size);
300 if (!object) {
301 return (NULL);
302 }
303 }
305 return (object);
306 }
307 #endif /* ACPI_USE_LOCAL_CACHE */