diff options
author | Dan Magenheimer <dan.magenheimer@oracle.com> | 2011-07-08 14:26:21 -0400 |
---|---|---|
committer | Dan Magenheimer <dan.magenheimer@oracle.com> | 2011-07-08 14:26:21 -0400 |
commit | a50777c791031d7345ce95785ea6220f67339d90 (patch) | |
tree | 8246cc346988df9cdaf3e2cea2b0e8eb20156fd7 /drivers/xen/xen-selfballoon.c | |
parent | 55922c9d1b84b89cb946c777fddccb3247e7df2c (diff) |
xen: tmem: self-ballooning and frontswap-selfshrinking
This patch introduces two in-kernel drivers for Xen transcendent memory
("tmem") functionality that complement cleancache and frontswap. Both
use control theory to dynamically adjust and optimize memory utilization.
Selfballooning controls the in-kernel Xen balloon driver, targeting a goal
value (vm_committed_as), thus pushing less frequently used clean
page cache pages (through the cleancache code) into Xen tmem where
Xen can balance needs across all VMs residing on the physical machine.
Frontswap-selfshrinking controls the number of pages in frontswap,
driving it towards zero (effectively doing a partial swapoff) when
in-kernel memory pressure subsides, freeing up RAM for other VMs.
More detail is provided in the header comment of xen-selfballooning.c.
Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com>
[v8: konrad.wilk@oracle.com: set default enablement depending on frontswap]
[v7: konrad.wilk@oracle.com: fix capitalization and punctuation in comments]
[v6: fix frontswap-selfshrinking initialization]
[v6: konrad.wilk@oracle.com: fix init pr_infos; add comments about swap]
[v5: konrad.wilk@oracle.com: add NULL to attr list; move inits up to decls]
[v4: dkiper@net-space.pl: use strict_strtoul plus a few syntactic nits]
[v3: konrad.wilk@oracle.com: fix potential divides-by-zero]
[v3: konrad.wilk@oracle.com: add many more comments, fix nits]
[v2: rebased to linux-3.0-rc1]
[v2: Ian.Campbell@citrix.com: reorganize as new file (xen-selfballoon.c)]
[v2: dkiper@net-space.pl: proper access to vm_committed_as]
[v2: dkiper@net-space.pl: accounting fixes]
Cc: Jan Beulich <JBeulich@novell.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: <xen-devel@lists.xensource.com>
Diffstat (limited to 'drivers/xen/xen-selfballoon.c')
-rw-r--r-- | drivers/xen/xen-selfballoon.c | 485 |
1 files changed, 485 insertions, 0 deletions
diff --git a/drivers/xen/xen-selfballoon.c b/drivers/xen/xen-selfballoon.c new file mode 100644 index 000000000000..010937b5a7c9 --- /dev/null +++ b/drivers/xen/xen-selfballoon.c | |||
@@ -0,0 +1,485 @@ | |||
1 | /****************************************************************************** | ||
2 | * Xen selfballoon driver (and optional frontswap self-shrinking driver) | ||
3 | * | ||
4 | * Copyright (c) 2009-2011, Dan Magenheimer, Oracle Corp. | ||
5 | * | ||
6 | * This code complements the cleancache and frontswap patchsets to optimize | ||
7 | * support for Xen Transcendent Memory ("tmem"). The policy it implements | ||
8 | * is rudimentary and will likely improve over time, but it does work well | ||
9 | * enough today. | ||
10 | * | ||
11 | * Two functionalities are implemented here which both use "control theory" | ||
12 | * (feedback) to optimize memory utilization. In a virtualized environment | ||
13 | * such as Xen, RAM is often a scarce resource and we would like to ensure | ||
14 | * that each of a possibly large number of virtual machines is using RAM | ||
15 | * efficiently, i.e. using as little as possible when under light load | ||
16 | * and obtaining as much as possible when memory demands are high. | ||
17 | * Since RAM needs vary highly dynamically and sometimes dramatically, | ||
18 | * "hysteresis" is used, that is, memory target is determined not just | ||
19 | * on current data but also on past data stored in the system. | ||
20 | * | ||
21 | * "Selfballooning" creates memory pressure by managing the Xen balloon | ||
22 | * driver to decrease and increase available kernel memory, driven | ||
23 | * largely by the target value of "Committed_AS" (see /proc/meminfo). | ||
24 | * Since Committed_AS does not account for clean mapped pages (i.e. pages | ||
25 | * in RAM that are identical to pages on disk), selfballooning has the | ||
26 | * affect of pushing less frequently used clean pagecache pages out of | ||
27 | * kernel RAM and, presumably using cleancache, into Xen tmem where | ||
28 | * Xen can more efficiently optimize RAM utilization for such pages. | ||
29 | * | ||
30 | * When kernel memory demand unexpectedly increases faster than Xen, via | ||
31 | * the selfballoon driver, is able to (or chooses to) provide usable RAM, | ||
32 | * the kernel may invoke swapping. In most cases, frontswap is able | ||
33 | * to absorb this swapping into Xen tmem. However, due to the fact | ||
34 | * that the kernel swap subsystem assumes swapping occurs to a disk, | ||
35 | * swapped pages may sit on the disk for a very long time; even if | ||
36 | * the kernel knows the page will never be used again. This is because | ||
37 | * the disk space costs very little and can be overwritten when | ||
38 | * necessary. When such stale pages are in frontswap, however, they | ||
39 | * are taking up valuable real estate. "Frontswap selfshrinking" works | ||
40 | * to resolve this: When frontswap activity is otherwise stable | ||
41 | * and the guest kernel is not under memory pressure, the "frontswap | ||
42 | * selfshrinking" accounts for this by providing pressure to remove some | ||
43 | * pages from frontswap and return them to kernel memory. | ||
44 | * | ||
45 | * For both "selfballooning" and "frontswap-selfshrinking", a worker | ||
46 | * thread is used and sysfs tunables are provided to adjust the frequency | ||
47 | * and rate of adjustments to achieve the goal, as well as to disable one | ||
48 | * or both functions independently. | ||
49 | * | ||
50 | * While some argue that this functionality can and should be implemented | ||
51 | * in userspace, it has been observed that bad things happen (e.g. OOMs). | ||
52 | * | ||
53 | * System configuration note: Selfballooning should not be enabled on | ||
54 | * systems without a sufficiently large swap device configured; for best | ||
55 | * results, it is recommended that total swap be increased by the size | ||
56 | * of the guest memory. Also, while technically not required to be | ||
57 | * configured, it is highly recommended that frontswap also be configured | ||
58 | * and enabled when selfballooning is running. So, selfballooning | ||
59 | * is disabled by default if frontswap is not configured and can only | ||
60 | * be enabled with the "selfballooning" kernel boot option; similarly | ||
61 | * selfballooning is enabled by default if frontswap is configured and | ||
62 | * can be disabled with the "noselfballooning" kernel boot option. Finally, | ||
63 | * when frontswap is configured, frontswap-selfshrinking can be disabled | ||
64 | * with the "noselfshrink" kernel boot option. | ||
65 | * | ||
66 | * Selfballooning is disallowed in domain0 and force-disabled. | ||
67 | * | ||
68 | */ | ||
69 | |||
70 | #include <linux/kernel.h> | ||
71 | #include <linux/mm.h> | ||
72 | #include <linux/mman.h> | ||
73 | |||
74 | #include <xen/balloon.h> | ||
75 | |||
76 | #include <xen/tmem.h> | ||
77 | |||
78 | /* Enable/disable with sysfs. */ | ||
79 | static int xen_selfballooning_enabled __read_mostly; | ||
80 | |||
81 | /* | ||
82 | * Controls rate at which memory target (this iteration) approaches | ||
83 | * ultimate goal when memory need is increasing (up-hysteresis) or | ||
84 | * decreasing (down-hysteresis). Higher values of hysteresis cause | ||
85 | * slower increases/decreases. The default values for the various | ||
86 | * parameters were deemed reasonable by experimentation, may be | ||
87 | * workload-dependent, and can all be adjusted via sysfs. | ||
88 | */ | ||
89 | static unsigned int selfballoon_downhysteresis __read_mostly = 8; | ||
90 | static unsigned int selfballoon_uphysteresis __read_mostly = 1; | ||
91 | |||
92 | /* In HZ, controls frequency of worker invocation. */ | ||
93 | static unsigned int selfballoon_interval __read_mostly = 5; | ||
94 | |||
95 | static void selfballoon_process(struct work_struct *work); | ||
96 | static DECLARE_DELAYED_WORK(selfballoon_worker, selfballoon_process); | ||
97 | |||
98 | #ifdef CONFIG_FRONTSWAP | ||
99 | #include <linux/frontswap.h> | ||
100 | |||
101 | /* Enable/disable with sysfs. */ | ||
102 | static bool frontswap_selfshrinking __read_mostly; | ||
103 | |||
104 | /* Enable/disable with kernel boot option. */ | ||
105 | static bool use_frontswap_selfshrink __initdata = true; | ||
106 | |||
107 | /* | ||
108 | * The default values for the following parameters were deemed reasonable | ||
109 | * by experimentation, may be workload-dependent, and can all be | ||
110 | * adjusted via sysfs. | ||
111 | */ | ||
112 | |||
113 | /* Control rate for frontswap shrinking. Higher hysteresis is slower. */ | ||
114 | static unsigned int frontswap_hysteresis __read_mostly = 20; | ||
115 | |||
116 | /* | ||
117 | * Number of selfballoon worker invocations to wait before observing that | ||
118 | * frontswap selfshrinking should commence. Note that selfshrinking does | ||
119 | * not use a separate worker thread. | ||
120 | */ | ||
121 | static unsigned int frontswap_inertia __read_mostly = 3; | ||
122 | |||
123 | /* Countdown to next invocation of frontswap_shrink() */ | ||
124 | static unsigned long frontswap_inertia_counter; | ||
125 | |||
126 | /* | ||
127 | * Invoked by the selfballoon worker thread, uses current number of pages | ||
128 | * in frontswap (frontswap_curr_pages()), previous status, and control | ||
129 | * values (hysteresis and inertia) to determine if frontswap should be | ||
130 | * shrunk and what the new frontswap size should be. Note that | ||
131 | * frontswap_shrink is essentially a partial swapoff that immediately | ||
132 | * transfers pages from the "swap device" (frontswap) back into kernel | ||
133 | * RAM; despite the name, frontswap "shrinking" is very different from | ||
134 | * the "shrinker" interface used by the kernel MM subsystem to reclaim | ||
135 | * memory. | ||
136 | */ | ||
137 | static void frontswap_selfshrink(void) | ||
138 | { | ||
139 | static unsigned long cur_frontswap_pages; | ||
140 | static unsigned long last_frontswap_pages; | ||
141 | static unsigned long tgt_frontswap_pages; | ||
142 | |||
143 | last_frontswap_pages = cur_frontswap_pages; | ||
144 | cur_frontswap_pages = frontswap_curr_pages(); | ||
145 | if (!cur_frontswap_pages || | ||
146 | (cur_frontswap_pages > last_frontswap_pages)) { | ||
147 | frontswap_inertia_counter = frontswap_inertia; | ||
148 | return; | ||
149 | } | ||
150 | if (frontswap_inertia_counter && --frontswap_inertia_counter) | ||
151 | return; | ||
152 | if (cur_frontswap_pages <= frontswap_hysteresis) | ||
153 | tgt_frontswap_pages = 0; | ||
154 | else | ||
155 | tgt_frontswap_pages = cur_frontswap_pages - | ||
156 | (cur_frontswap_pages / frontswap_hysteresis); | ||
157 | frontswap_shrink(tgt_frontswap_pages); | ||
158 | } | ||
159 | |||
160 | static int __init xen_nofrontswap_selfshrink_setup(char *s) | ||
161 | { | ||
162 | use_frontswap_selfshrink = false; | ||
163 | return 1; | ||
164 | } | ||
165 | |||
166 | __setup("noselfshrink", xen_nofrontswap_selfshrink_setup); | ||
167 | |||
168 | /* Disable with kernel boot option. */ | ||
169 | static bool use_selfballooning __initdata = true; | ||
170 | |||
171 | static int __init xen_noselfballooning_setup(char *s) | ||
172 | { | ||
173 | use_selfballooning = false; | ||
174 | return 1; | ||
175 | } | ||
176 | |||
177 | __setup("noselfballooning", xen_noselfballooning_setup); | ||
178 | #else /* !CONFIG_FRONTSWAP */ | ||
179 | /* Enable with kernel boot option. */ | ||
180 | static bool use_selfballooning __initdata = false; | ||
181 | |||
182 | static int __init xen_selfballooning_setup(char *s) | ||
183 | { | ||
184 | use_selfballooning = true; | ||
185 | return 1; | ||
186 | } | ||
187 | |||
188 | __setup("selfballooning", xen_selfballooning_setup); | ||
189 | #endif /* CONFIG_FRONTSWAP */ | ||
190 | |||
191 | /* | ||
192 | * Use current balloon size, the goal (vm_committed_as), and hysteresis | ||
193 | * parameters to set a new target balloon size | ||
194 | */ | ||
195 | static void selfballoon_process(struct work_struct *work) | ||
196 | { | ||
197 | unsigned long cur_pages, goal_pages, tgt_pages; | ||
198 | bool reset_timer = false; | ||
199 | |||
200 | if (xen_selfballooning_enabled) { | ||
201 | cur_pages = balloon_stats.current_pages; | ||
202 | tgt_pages = cur_pages; /* default is no change */ | ||
203 | goal_pages = percpu_counter_read_positive(&vm_committed_as) + | ||
204 | balloon_stats.current_pages - totalram_pages; | ||
205 | #ifdef CONFIG_FRONTSWAP | ||
206 | /* allow space for frontswap pages to be repatriated */ | ||
207 | if (frontswap_selfshrinking && frontswap_enabled) | ||
208 | goal_pages += frontswap_curr_pages(); | ||
209 | #endif | ||
210 | if (cur_pages > goal_pages) | ||
211 | tgt_pages = cur_pages - | ||
212 | ((cur_pages - goal_pages) / | ||
213 | selfballoon_downhysteresis); | ||
214 | else if (cur_pages < goal_pages) | ||
215 | tgt_pages = cur_pages + | ||
216 | ((goal_pages - cur_pages) / | ||
217 | selfballoon_uphysteresis); | ||
218 | /* else if cur_pages == goal_pages, no change */ | ||
219 | balloon_set_new_target(tgt_pages); | ||
220 | reset_timer = true; | ||
221 | } | ||
222 | #ifdef CONFIG_FRONTSWAP | ||
223 | if (frontswap_selfshrinking && frontswap_enabled) { | ||
224 | frontswap_selfshrink(); | ||
225 | reset_timer = true; | ||
226 | } | ||
227 | #endif | ||
228 | if (reset_timer) | ||
229 | schedule_delayed_work(&selfballoon_worker, | ||
230 | selfballoon_interval * HZ); | ||
231 | } | ||
232 | |||
233 | #ifdef CONFIG_SYSFS | ||
234 | |||
235 | #include <linux/sysdev.h> | ||
236 | #include <linux/capability.h> | ||
237 | |||
238 | #define SELFBALLOON_SHOW(name, format, args...) \ | ||
239 | static ssize_t show_##name(struct sys_device *dev, \ | ||
240 | struct sysdev_attribute *attr, \ | ||
241 | char *buf) \ | ||
242 | { \ | ||
243 | return sprintf(buf, format, ##args); \ | ||
244 | } | ||
245 | |||
246 | SELFBALLOON_SHOW(selfballooning, "%d\n", xen_selfballooning_enabled); | ||
247 | |||
248 | static ssize_t store_selfballooning(struct sys_device *dev, | ||
249 | struct sysdev_attribute *attr, | ||
250 | const char *buf, | ||
251 | size_t count) | ||
252 | { | ||
253 | bool was_enabled = xen_selfballooning_enabled; | ||
254 | unsigned long tmp; | ||
255 | int err; | ||
256 | |||
257 | if (!capable(CAP_SYS_ADMIN)) | ||
258 | return -EPERM; | ||
259 | |||
260 | err = strict_strtoul(buf, 10, &tmp); | ||
261 | if (err || ((tmp != 0) && (tmp != 1))) | ||
262 | return -EINVAL; | ||
263 | |||
264 | xen_selfballooning_enabled = !!tmp; | ||
265 | if (!was_enabled && xen_selfballooning_enabled) | ||
266 | schedule_delayed_work(&selfballoon_worker, | ||
267 | selfballoon_interval * HZ); | ||
268 | |||
269 | return count; | ||
270 | } | ||
271 | |||
272 | static SYSDEV_ATTR(selfballooning, S_IRUGO | S_IWUSR, | ||
273 | show_selfballooning, store_selfballooning); | ||
274 | |||
275 | SELFBALLOON_SHOW(selfballoon_interval, "%d\n", selfballoon_interval); | ||
276 | |||
277 | static ssize_t store_selfballoon_interval(struct sys_device *dev, | ||
278 | struct sysdev_attribute *attr, | ||
279 | const char *buf, | ||
280 | size_t count) | ||
281 | { | ||
282 | unsigned long val; | ||
283 | int err; | ||
284 | |||
285 | if (!capable(CAP_SYS_ADMIN)) | ||
286 | return -EPERM; | ||
287 | err = strict_strtoul(buf, 10, &val); | ||
288 | if (err || val == 0) | ||
289 | return -EINVAL; | ||
290 | selfballoon_interval = val; | ||
291 | return count; | ||
292 | } | ||
293 | |||
294 | static SYSDEV_ATTR(selfballoon_interval, S_IRUGO | S_IWUSR, | ||
295 | show_selfballoon_interval, store_selfballoon_interval); | ||
296 | |||
297 | SELFBALLOON_SHOW(selfballoon_downhys, "%d\n", selfballoon_downhysteresis); | ||
298 | |||
299 | static ssize_t store_selfballoon_downhys(struct sys_device *dev, | ||
300 | struct sysdev_attribute *attr, | ||
301 | const char *buf, | ||
302 | size_t count) | ||
303 | { | ||
304 | unsigned long val; | ||
305 | int err; | ||
306 | |||
307 | if (!capable(CAP_SYS_ADMIN)) | ||
308 | return -EPERM; | ||
309 | err = strict_strtoul(buf, 10, &val); | ||
310 | if (err || val == 0) | ||
311 | return -EINVAL; | ||
312 | selfballoon_downhysteresis = val; | ||
313 | return count; | ||
314 | } | ||
315 | |||
316 | static SYSDEV_ATTR(selfballoon_downhysteresis, S_IRUGO | S_IWUSR, | ||
317 | show_selfballoon_downhys, store_selfballoon_downhys); | ||
318 | |||
319 | |||
320 | SELFBALLOON_SHOW(selfballoon_uphys, "%d\n", selfballoon_uphysteresis); | ||
321 | |||
322 | static ssize_t store_selfballoon_uphys(struct sys_device *dev, | ||
323 | struct sysdev_attribute *attr, | ||
324 | const char *buf, | ||
325 | size_t count) | ||
326 | { | ||
327 | unsigned long val; | ||
328 | int err; | ||
329 | |||
330 | if (!capable(CAP_SYS_ADMIN)) | ||
331 | return -EPERM; | ||
332 | err = strict_strtoul(buf, 10, &val); | ||
333 | if (err || val == 0) | ||
334 | return -EINVAL; | ||
335 | selfballoon_uphysteresis = val; | ||
336 | return count; | ||
337 | } | ||
338 | |||
339 | static SYSDEV_ATTR(selfballoon_uphysteresis, S_IRUGO | S_IWUSR, | ||
340 | show_selfballoon_uphys, store_selfballoon_uphys); | ||
341 | |||
342 | #ifdef CONFIG_FRONTSWAP | ||
343 | SELFBALLOON_SHOW(frontswap_selfshrinking, "%d\n", frontswap_selfshrinking); | ||
344 | |||
345 | static ssize_t store_frontswap_selfshrinking(struct sys_device *dev, | ||
346 | struct sysdev_attribute *attr, | ||
347 | const char *buf, | ||
348 | size_t count) | ||
349 | { | ||
350 | bool was_enabled = frontswap_selfshrinking; | ||
351 | unsigned long tmp; | ||
352 | int err; | ||
353 | |||
354 | if (!capable(CAP_SYS_ADMIN)) | ||
355 | return -EPERM; | ||
356 | err = strict_strtoul(buf, 10, &tmp); | ||
357 | if (err || ((tmp != 0) && (tmp != 1))) | ||
358 | return -EINVAL; | ||
359 | frontswap_selfshrinking = !!tmp; | ||
360 | if (!was_enabled && !xen_selfballooning_enabled && | ||
361 | frontswap_selfshrinking) | ||
362 | schedule_delayed_work(&selfballoon_worker, | ||
363 | selfballoon_interval * HZ); | ||
364 | |||
365 | return count; | ||
366 | } | ||
367 | |||
368 | static SYSDEV_ATTR(frontswap_selfshrinking, S_IRUGO | S_IWUSR, | ||
369 | show_frontswap_selfshrinking, store_frontswap_selfshrinking); | ||
370 | |||
371 | SELFBALLOON_SHOW(frontswap_inertia, "%d\n", frontswap_inertia); | ||
372 | |||
373 | static ssize_t store_frontswap_inertia(struct sys_device *dev, | ||
374 | struct sysdev_attribute *attr, | ||
375 | const char *buf, | ||
376 | size_t count) | ||
377 | { | ||
378 | unsigned long val; | ||
379 | int err; | ||
380 | |||
381 | if (!capable(CAP_SYS_ADMIN)) | ||
382 | return -EPERM; | ||
383 | err = strict_strtoul(buf, 10, &val); | ||
384 | if (err || val == 0) | ||
385 | return -EINVAL; | ||
386 | frontswap_inertia = val; | ||
387 | frontswap_inertia_counter = val; | ||
388 | return count; | ||
389 | } | ||
390 | |||
391 | static SYSDEV_ATTR(frontswap_inertia, S_IRUGO | S_IWUSR, | ||
392 | show_frontswap_inertia, store_frontswap_inertia); | ||
393 | |||
394 | SELFBALLOON_SHOW(frontswap_hysteresis, "%d\n", frontswap_hysteresis); | ||
395 | |||
396 | static ssize_t store_frontswap_hysteresis(struct sys_device *dev, | ||
397 | struct sysdev_attribute *attr, | ||
398 | const char *buf, | ||
399 | size_t count) | ||
400 | { | ||
401 | unsigned long val; | ||
402 | int err; | ||
403 | |||
404 | if (!capable(CAP_SYS_ADMIN)) | ||
405 | return -EPERM; | ||
406 | err = strict_strtoul(buf, 10, &val); | ||
407 | if (err || val == 0) | ||
408 | return -EINVAL; | ||
409 | frontswap_hysteresis = val; | ||
410 | return count; | ||
411 | } | ||
412 | |||
413 | static SYSDEV_ATTR(frontswap_hysteresis, S_IRUGO | S_IWUSR, | ||
414 | show_frontswap_hysteresis, store_frontswap_hysteresis); | ||
415 | |||
416 | #endif /* CONFIG_FRONTSWAP */ | ||
417 | |||
418 | static struct attribute *selfballoon_attrs[] = { | ||
419 | &attr_selfballooning.attr, | ||
420 | &attr_selfballoon_interval.attr, | ||
421 | &attr_selfballoon_downhysteresis.attr, | ||
422 | &attr_selfballoon_uphysteresis.attr, | ||
423 | #ifdef CONFIG_FRONTSWAP | ||
424 | &attr_frontswap_selfshrinking.attr, | ||
425 | &attr_frontswap_hysteresis.attr, | ||
426 | &attr_frontswap_inertia.attr, | ||
427 | #endif | ||
428 | NULL | ||
429 | }; | ||
430 | |||
431 | static struct attribute_group selfballoon_group = { | ||
432 | .name = "selfballoon", | ||
433 | .attrs = selfballoon_attrs | ||
434 | }; | ||
435 | #endif | ||
436 | |||
437 | int register_xen_selfballooning(struct sys_device *sysdev) | ||
438 | { | ||
439 | int error = -1; | ||
440 | |||
441 | #ifdef CONFIG_SYSFS | ||
442 | error = sysfs_create_group(&sysdev->kobj, &selfballoon_group); | ||
443 | #endif | ||
444 | return error; | ||
445 | } | ||
446 | EXPORT_SYMBOL(register_xen_selfballooning); | ||
447 | |||
448 | static int __init xen_selfballoon_init(void) | ||
449 | { | ||
450 | bool enable = false; | ||
451 | |||
452 | if (!xen_domain()) | ||
453 | return -ENODEV; | ||
454 | |||
455 | if (xen_initial_domain()) { | ||
456 | pr_info("xen/balloon: Xen selfballooning driver " | ||
457 | "disabled for domain0.\n"); | ||
458 | return -ENODEV; | ||
459 | } | ||
460 | |||
461 | xen_selfballooning_enabled = tmem_enabled && use_selfballooning; | ||
462 | if (xen_selfballooning_enabled) { | ||
463 | pr_info("xen/balloon: Initializing Xen " | ||
464 | "selfballooning driver.\n"); | ||
465 | enable = true; | ||
466 | } | ||
467 | #ifdef CONFIG_FRONTSWAP | ||
468 | frontswap_selfshrinking = tmem_enabled && use_frontswap_selfshrink; | ||
469 | if (frontswap_selfshrinking) { | ||
470 | pr_info("xen/balloon: Initializing frontswap " | ||
471 | "selfshrinking driver.\n"); | ||
472 | enable = true; | ||
473 | } | ||
474 | #endif | ||
475 | if (!enable) | ||
476 | return -ENODEV; | ||
477 | |||
478 | schedule_delayed_work(&selfballoon_worker, selfballoon_interval * HZ); | ||
479 | |||
480 | return 0; | ||
481 | } | ||
482 | |||
483 | subsys_initcall(xen_selfballoon_init); | ||
484 | |||
485 | MODULE_LICENSE("GPL"); | ||