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a50777c7 DM |
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 | |
37d46e15 KRW |
56 | * of the guest memory. Note, that selfballooning should be disabled by default |
57 | * if frontswap is not configured. Similarly selfballooning should be enabled | |
58 | * by default if frontswap is configured and can be disabled with the | |
59 | * "tmem.selfballooning=0" kernel boot option. Finally, when frontswap is | |
60 | * configured, frontswap-selfshrinking can be disabled with the | |
61 | * "tmem.selfshrink=0" kernel boot option. | |
a50777c7 DM |
62 | * |
63 | * Selfballooning is disallowed in domain0 and force-disabled. | |
64 | * | |
65 | */ | |
66 | ||
67 | #include <linux/kernel.h> | |
38a1ed4f DM |
68 | #include <linux/bootmem.h> |
69 | #include <linux/swap.h> | |
a50777c7 DM |
70 | #include <linux/mm.h> |
71 | #include <linux/mman.h> | |
4fec0e0b | 72 | #include <linux/module.h> |
0642d2ed | 73 | #include <linux/workqueue.h> |
cb0c05c5 | 74 | #include <linux/device.h> |
a50777c7 | 75 | #include <xen/balloon.h> |
a50777c7 | 76 | #include <xen/tmem.h> |
0642d2ed | 77 | #include <xen/xen.h> |
a50777c7 DM |
78 | |
79 | /* Enable/disable with sysfs. */ | |
80 | static int xen_selfballooning_enabled __read_mostly; | |
81 | ||
82 | /* | |
83 | * Controls rate at which memory target (this iteration) approaches | |
84 | * ultimate goal when memory need is increasing (up-hysteresis) or | |
85 | * decreasing (down-hysteresis). Higher values of hysteresis cause | |
86 | * slower increases/decreases. The default values for the various | |
87 | * parameters were deemed reasonable by experimentation, may be | |
88 | * workload-dependent, and can all be adjusted via sysfs. | |
89 | */ | |
90 | static unsigned int selfballoon_downhysteresis __read_mostly = 8; | |
91 | static unsigned int selfballoon_uphysteresis __read_mostly = 1; | |
92 | ||
93 | /* In HZ, controls frequency of worker invocation. */ | |
94 | static unsigned int selfballoon_interval __read_mostly = 5; | |
95 | ||
38a1ed4f DM |
96 | /* |
97 | * Minimum usable RAM in MB for selfballooning target for balloon. | |
98 | * If non-zero, it is added to totalreserve_pages and self-ballooning | |
99 | * will not balloon below the sum. If zero, a piecewise linear function | |
100 | * is calculated as a minimum and added to totalreserve_pages. Note that | |
101 | * setting this value indiscriminately may cause OOMs and crashes. | |
102 | */ | |
103 | static unsigned int selfballoon_min_usable_mb; | |
104 | ||
d79d5959 JS |
105 | /* |
106 | * Amount of RAM in MB to add to the target number of pages. | |
107 | * Can be used to reserve some more room for caches and the like. | |
108 | */ | |
109 | static unsigned int selfballoon_reserved_mb; | |
110 | ||
a50777c7 DM |
111 | static void selfballoon_process(struct work_struct *work); |
112 | static DECLARE_DELAYED_WORK(selfballoon_worker, selfballoon_process); | |
113 | ||
114 | #ifdef CONFIG_FRONTSWAP | |
115 | #include <linux/frontswap.h> | |
116 | ||
117 | /* Enable/disable with sysfs. */ | |
118 | static bool frontswap_selfshrinking __read_mostly; | |
119 | ||
a50777c7 DM |
120 | /* |
121 | * The default values for the following parameters were deemed reasonable | |
122 | * by experimentation, may be workload-dependent, and can all be | |
123 | * adjusted via sysfs. | |
124 | */ | |
125 | ||
126 | /* Control rate for frontswap shrinking. Higher hysteresis is slower. */ | |
127 | static unsigned int frontswap_hysteresis __read_mostly = 20; | |
128 | ||
129 | /* | |
130 | * Number of selfballoon worker invocations to wait before observing that | |
131 | * frontswap selfshrinking should commence. Note that selfshrinking does | |
132 | * not use a separate worker thread. | |
133 | */ | |
134 | static unsigned int frontswap_inertia __read_mostly = 3; | |
135 | ||
136 | /* Countdown to next invocation of frontswap_shrink() */ | |
137 | static unsigned long frontswap_inertia_counter; | |
138 | ||
139 | /* | |
140 | * Invoked by the selfballoon worker thread, uses current number of pages | |
141 | * in frontswap (frontswap_curr_pages()), previous status, and control | |
142 | * values (hysteresis and inertia) to determine if frontswap should be | |
143 | * shrunk and what the new frontswap size should be. Note that | |
144 | * frontswap_shrink is essentially a partial swapoff that immediately | |
145 | * transfers pages from the "swap device" (frontswap) back into kernel | |
146 | * RAM; despite the name, frontswap "shrinking" is very different from | |
147 | * the "shrinker" interface used by the kernel MM subsystem to reclaim | |
148 | * memory. | |
149 | */ | |
150 | static void frontswap_selfshrink(void) | |
151 | { | |
152 | static unsigned long cur_frontswap_pages; | |
153 | static unsigned long last_frontswap_pages; | |
154 | static unsigned long tgt_frontswap_pages; | |
155 | ||
156 | last_frontswap_pages = cur_frontswap_pages; | |
157 | cur_frontswap_pages = frontswap_curr_pages(); | |
158 | if (!cur_frontswap_pages || | |
159 | (cur_frontswap_pages > last_frontswap_pages)) { | |
160 | frontswap_inertia_counter = frontswap_inertia; | |
161 | return; | |
162 | } | |
163 | if (frontswap_inertia_counter && --frontswap_inertia_counter) | |
164 | return; | |
165 | if (cur_frontswap_pages <= frontswap_hysteresis) | |
166 | tgt_frontswap_pages = 0; | |
167 | else | |
168 | tgt_frontswap_pages = cur_frontswap_pages - | |
169 | (cur_frontswap_pages / frontswap_hysteresis); | |
170 | frontswap_shrink(tgt_frontswap_pages); | |
171 | } | |
172 | ||
a50777c7 DM |
173 | #endif /* CONFIG_FRONTSWAP */ |
174 | ||
38a1ed4f DM |
175 | #define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT)) |
176 | ||
a50777c7 DM |
177 | /* |
178 | * Use current balloon size, the goal (vm_committed_as), and hysteresis | |
179 | * parameters to set a new target balloon size | |
180 | */ | |
181 | static void selfballoon_process(struct work_struct *work) | |
182 | { | |
38a1ed4f DM |
183 | unsigned long cur_pages, goal_pages, tgt_pages, floor_pages; |
184 | unsigned long useful_pages; | |
a50777c7 DM |
185 | bool reset_timer = false; |
186 | ||
187 | if (xen_selfballooning_enabled) { | |
38a1ed4f | 188 | cur_pages = totalram_pages; |
a50777c7 | 189 | tgt_pages = cur_pages; /* default is no change */ |
997071bc | 190 | goal_pages = vm_memory_committed() + |
d79d5959 JS |
191 | totalreserve_pages + |
192 | MB2PAGES(selfballoon_reserved_mb); | |
a50777c7 DM |
193 | #ifdef CONFIG_FRONTSWAP |
194 | /* allow space for frontswap pages to be repatriated */ | |
195 | if (frontswap_selfshrinking && frontswap_enabled) | |
196 | goal_pages += frontswap_curr_pages(); | |
197 | #endif | |
198 | if (cur_pages > goal_pages) | |
199 | tgt_pages = cur_pages - | |
200 | ((cur_pages - goal_pages) / | |
201 | selfballoon_downhysteresis); | |
202 | else if (cur_pages < goal_pages) | |
203 | tgt_pages = cur_pages + | |
204 | ((goal_pages - cur_pages) / | |
205 | selfballoon_uphysteresis); | |
206 | /* else if cur_pages == goal_pages, no change */ | |
38a1ed4f DM |
207 | useful_pages = max_pfn - totalreserve_pages; |
208 | if (selfballoon_min_usable_mb != 0) | |
209 | floor_pages = totalreserve_pages + | |
210 | MB2PAGES(selfballoon_min_usable_mb); | |
211 | /* piecewise linear function ending in ~3% slope */ | |
212 | else if (useful_pages < MB2PAGES(16)) | |
213 | floor_pages = max_pfn; /* not worth ballooning */ | |
214 | else if (useful_pages < MB2PAGES(64)) | |
215 | floor_pages = totalreserve_pages + MB2PAGES(16) + | |
216 | ((useful_pages - MB2PAGES(16)) >> 1); | |
217 | else if (useful_pages < MB2PAGES(512)) | |
218 | floor_pages = totalreserve_pages + MB2PAGES(40) + | |
219 | ((useful_pages - MB2PAGES(40)) >> 3); | |
220 | else /* useful_pages >= MB2PAGES(512) */ | |
221 | floor_pages = totalreserve_pages + MB2PAGES(99) + | |
222 | ((useful_pages - MB2PAGES(99)) >> 5); | |
223 | if (tgt_pages < floor_pages) | |
224 | tgt_pages = floor_pages; | |
225 | balloon_set_new_target(tgt_pages + | |
226 | balloon_stats.current_pages - totalram_pages); | |
a50777c7 DM |
227 | reset_timer = true; |
228 | } | |
229 | #ifdef CONFIG_FRONTSWAP | |
230 | if (frontswap_selfshrinking && frontswap_enabled) { | |
231 | frontswap_selfshrink(); | |
232 | reset_timer = true; | |
233 | } | |
234 | #endif | |
235 | if (reset_timer) | |
236 | schedule_delayed_work(&selfballoon_worker, | |
237 | selfballoon_interval * HZ); | |
238 | } | |
239 | ||
240 | #ifdef CONFIG_SYSFS | |
241 | ||
a50777c7 DM |
242 | #include <linux/capability.h> |
243 | ||
244 | #define SELFBALLOON_SHOW(name, format, args...) \ | |
07068021 KS |
245 | static ssize_t show_##name(struct device *dev, \ |
246 | struct device_attribute *attr, \ | |
247 | char *buf) \ | |
a50777c7 DM |
248 | { \ |
249 | return sprintf(buf, format, ##args); \ | |
250 | } | |
251 | ||
252 | SELFBALLOON_SHOW(selfballooning, "%d\n", xen_selfballooning_enabled); | |
253 | ||
07068021 KS |
254 | static ssize_t store_selfballooning(struct device *dev, |
255 | struct device_attribute *attr, | |
a50777c7 DM |
256 | const char *buf, |
257 | size_t count) | |
258 | { | |
259 | bool was_enabled = xen_selfballooning_enabled; | |
260 | unsigned long tmp; | |
261 | int err; | |
262 | ||
263 | if (!capable(CAP_SYS_ADMIN)) | |
264 | return -EPERM; | |
265 | ||
266 | err = strict_strtoul(buf, 10, &tmp); | |
267 | if (err || ((tmp != 0) && (tmp != 1))) | |
268 | return -EINVAL; | |
269 | ||
270 | xen_selfballooning_enabled = !!tmp; | |
271 | if (!was_enabled && xen_selfballooning_enabled) | |
272 | schedule_delayed_work(&selfballoon_worker, | |
273 | selfballoon_interval * HZ); | |
274 | ||
275 | return count; | |
276 | } | |
277 | ||
07068021 | 278 | static DEVICE_ATTR(selfballooning, S_IRUGO | S_IWUSR, |
a50777c7 DM |
279 | show_selfballooning, store_selfballooning); |
280 | ||
281 | SELFBALLOON_SHOW(selfballoon_interval, "%d\n", selfballoon_interval); | |
282 | ||
07068021 KS |
283 | static ssize_t store_selfballoon_interval(struct device *dev, |
284 | struct device_attribute *attr, | |
a50777c7 DM |
285 | const char *buf, |
286 | size_t count) | |
287 | { | |
288 | unsigned long val; | |
289 | int err; | |
290 | ||
291 | if (!capable(CAP_SYS_ADMIN)) | |
292 | return -EPERM; | |
293 | err = strict_strtoul(buf, 10, &val); | |
294 | if (err || val == 0) | |
295 | return -EINVAL; | |
296 | selfballoon_interval = val; | |
297 | return count; | |
298 | } | |
299 | ||
07068021 | 300 | static DEVICE_ATTR(selfballoon_interval, S_IRUGO | S_IWUSR, |
a50777c7 DM |
301 | show_selfballoon_interval, store_selfballoon_interval); |
302 | ||
303 | SELFBALLOON_SHOW(selfballoon_downhys, "%d\n", selfballoon_downhysteresis); | |
304 | ||
07068021 KS |
305 | static ssize_t store_selfballoon_downhys(struct device *dev, |
306 | struct device_attribute *attr, | |
a50777c7 DM |
307 | const char *buf, |
308 | size_t count) | |
309 | { | |
310 | unsigned long val; | |
311 | int err; | |
312 | ||
313 | if (!capable(CAP_SYS_ADMIN)) | |
314 | return -EPERM; | |
315 | err = strict_strtoul(buf, 10, &val); | |
316 | if (err || val == 0) | |
317 | return -EINVAL; | |
318 | selfballoon_downhysteresis = val; | |
319 | return count; | |
320 | } | |
321 | ||
07068021 | 322 | static DEVICE_ATTR(selfballoon_downhysteresis, S_IRUGO | S_IWUSR, |
a50777c7 DM |
323 | show_selfballoon_downhys, store_selfballoon_downhys); |
324 | ||
325 | ||
326 | SELFBALLOON_SHOW(selfballoon_uphys, "%d\n", selfballoon_uphysteresis); | |
327 | ||
07068021 KS |
328 | static ssize_t store_selfballoon_uphys(struct device *dev, |
329 | struct device_attribute *attr, | |
a50777c7 DM |
330 | const char *buf, |
331 | size_t count) | |
332 | { | |
333 | unsigned long val; | |
334 | int err; | |
335 | ||
336 | if (!capable(CAP_SYS_ADMIN)) | |
337 | return -EPERM; | |
338 | err = strict_strtoul(buf, 10, &val); | |
339 | if (err || val == 0) | |
340 | return -EINVAL; | |
341 | selfballoon_uphysteresis = val; | |
342 | return count; | |
343 | } | |
344 | ||
07068021 | 345 | static DEVICE_ATTR(selfballoon_uphysteresis, S_IRUGO | S_IWUSR, |
a50777c7 DM |
346 | show_selfballoon_uphys, store_selfballoon_uphys); |
347 | ||
38a1ed4f DM |
348 | SELFBALLOON_SHOW(selfballoon_min_usable_mb, "%d\n", |
349 | selfballoon_min_usable_mb); | |
350 | ||
07068021 KS |
351 | static ssize_t store_selfballoon_min_usable_mb(struct device *dev, |
352 | struct device_attribute *attr, | |
38a1ed4f DM |
353 | const char *buf, |
354 | size_t count) | |
355 | { | |
356 | unsigned long val; | |
357 | int err; | |
358 | ||
359 | if (!capable(CAP_SYS_ADMIN)) | |
360 | return -EPERM; | |
361 | err = strict_strtoul(buf, 10, &val); | |
362 | if (err || val == 0) | |
363 | return -EINVAL; | |
364 | selfballoon_min_usable_mb = val; | |
365 | return count; | |
366 | } | |
367 | ||
07068021 | 368 | static DEVICE_ATTR(selfballoon_min_usable_mb, S_IRUGO | S_IWUSR, |
38a1ed4f DM |
369 | show_selfballoon_min_usable_mb, |
370 | store_selfballoon_min_usable_mb); | |
371 | ||
d79d5959 JS |
372 | SELFBALLOON_SHOW(selfballoon_reserved_mb, "%d\n", |
373 | selfballoon_reserved_mb); | |
374 | ||
375 | static ssize_t store_selfballoon_reserved_mb(struct device *dev, | |
376 | struct device_attribute *attr, | |
377 | const char *buf, | |
378 | size_t count) | |
379 | { | |
380 | unsigned long val; | |
381 | int err; | |
382 | ||
383 | if (!capable(CAP_SYS_ADMIN)) | |
384 | return -EPERM; | |
385 | err = strict_strtoul(buf, 10, &val); | |
386 | if (err || val == 0) | |
387 | return -EINVAL; | |
388 | selfballoon_reserved_mb = val; | |
389 | return count; | |
390 | } | |
391 | ||
392 | static DEVICE_ATTR(selfballoon_reserved_mb, S_IRUGO | S_IWUSR, | |
393 | show_selfballoon_reserved_mb, | |
394 | store_selfballoon_reserved_mb); | |
395 | ||
38a1ed4f | 396 | |
a50777c7 DM |
397 | #ifdef CONFIG_FRONTSWAP |
398 | SELFBALLOON_SHOW(frontswap_selfshrinking, "%d\n", frontswap_selfshrinking); | |
399 | ||
07068021 KS |
400 | static ssize_t store_frontswap_selfshrinking(struct device *dev, |
401 | struct device_attribute *attr, | |
a50777c7 DM |
402 | const char *buf, |
403 | size_t count) | |
404 | { | |
405 | bool was_enabled = frontswap_selfshrinking; | |
406 | unsigned long tmp; | |
407 | int err; | |
408 | ||
409 | if (!capable(CAP_SYS_ADMIN)) | |
410 | return -EPERM; | |
411 | err = strict_strtoul(buf, 10, &tmp); | |
412 | if (err || ((tmp != 0) && (tmp != 1))) | |
413 | return -EINVAL; | |
414 | frontswap_selfshrinking = !!tmp; | |
415 | if (!was_enabled && !xen_selfballooning_enabled && | |
416 | frontswap_selfshrinking) | |
417 | schedule_delayed_work(&selfballoon_worker, | |
418 | selfballoon_interval * HZ); | |
419 | ||
420 | return count; | |
421 | } | |
422 | ||
07068021 | 423 | static DEVICE_ATTR(frontswap_selfshrinking, S_IRUGO | S_IWUSR, |
a50777c7 DM |
424 | show_frontswap_selfshrinking, store_frontswap_selfshrinking); |
425 | ||
426 | SELFBALLOON_SHOW(frontswap_inertia, "%d\n", frontswap_inertia); | |
427 | ||
07068021 KS |
428 | static ssize_t store_frontswap_inertia(struct device *dev, |
429 | struct device_attribute *attr, | |
a50777c7 DM |
430 | const char *buf, |
431 | size_t count) | |
432 | { | |
433 | unsigned long val; | |
434 | int err; | |
435 | ||
436 | if (!capable(CAP_SYS_ADMIN)) | |
437 | return -EPERM; | |
438 | err = strict_strtoul(buf, 10, &val); | |
439 | if (err || val == 0) | |
440 | return -EINVAL; | |
441 | frontswap_inertia = val; | |
442 | frontswap_inertia_counter = val; | |
443 | return count; | |
444 | } | |
445 | ||
07068021 | 446 | static DEVICE_ATTR(frontswap_inertia, S_IRUGO | S_IWUSR, |
a50777c7 DM |
447 | show_frontswap_inertia, store_frontswap_inertia); |
448 | ||
449 | SELFBALLOON_SHOW(frontswap_hysteresis, "%d\n", frontswap_hysteresis); | |
450 | ||
07068021 KS |
451 | static ssize_t store_frontswap_hysteresis(struct device *dev, |
452 | struct device_attribute *attr, | |
a50777c7 DM |
453 | const char *buf, |
454 | size_t count) | |
455 | { | |
456 | unsigned long val; | |
457 | int err; | |
458 | ||
459 | if (!capable(CAP_SYS_ADMIN)) | |
460 | return -EPERM; | |
461 | err = strict_strtoul(buf, 10, &val); | |
462 | if (err || val == 0) | |
463 | return -EINVAL; | |
464 | frontswap_hysteresis = val; | |
465 | return count; | |
466 | } | |
467 | ||
07068021 | 468 | static DEVICE_ATTR(frontswap_hysteresis, S_IRUGO | S_IWUSR, |
a50777c7 DM |
469 | show_frontswap_hysteresis, store_frontswap_hysteresis); |
470 | ||
471 | #endif /* CONFIG_FRONTSWAP */ | |
472 | ||
473 | static struct attribute *selfballoon_attrs[] = { | |
07068021 KS |
474 | &dev_attr_selfballooning.attr, |
475 | &dev_attr_selfballoon_interval.attr, | |
476 | &dev_attr_selfballoon_downhysteresis.attr, | |
477 | &dev_attr_selfballoon_uphysteresis.attr, | |
478 | &dev_attr_selfballoon_min_usable_mb.attr, | |
d79d5959 | 479 | &dev_attr_selfballoon_reserved_mb.attr, |
a50777c7 | 480 | #ifdef CONFIG_FRONTSWAP |
07068021 KS |
481 | &dev_attr_frontswap_selfshrinking.attr, |
482 | &dev_attr_frontswap_hysteresis.attr, | |
483 | &dev_attr_frontswap_inertia.attr, | |
a50777c7 DM |
484 | #endif |
485 | NULL | |
486 | }; | |
487 | ||
ead1d014 | 488 | static const struct attribute_group selfballoon_group = { |
a50777c7 DM |
489 | .name = "selfballoon", |
490 | .attrs = selfballoon_attrs | |
491 | }; | |
492 | #endif | |
493 | ||
07068021 | 494 | int register_xen_selfballooning(struct device *dev) |
a50777c7 DM |
495 | { |
496 | int error = -1; | |
497 | ||
498 | #ifdef CONFIG_SYSFS | |
07068021 | 499 | error = sysfs_create_group(&dev->kobj, &selfballoon_group); |
a50777c7 DM |
500 | #endif |
501 | return error; | |
502 | } | |
503 | EXPORT_SYMBOL(register_xen_selfballooning); | |
504 | ||
10a7a077 | 505 | int xen_selfballoon_init(bool use_selfballooning, bool use_frontswap_selfshrink) |
a50777c7 DM |
506 | { |
507 | bool enable = false; | |
508 | ||
509 | if (!xen_domain()) | |
510 | return -ENODEV; | |
511 | ||
512 | if (xen_initial_domain()) { | |
513 | pr_info("xen/balloon: Xen selfballooning driver " | |
514 | "disabled for domain0.\n"); | |
515 | return -ENODEV; | |
516 | } | |
517 | ||
518 | xen_selfballooning_enabled = tmem_enabled && use_selfballooning; | |
519 | if (xen_selfballooning_enabled) { | |
520 | pr_info("xen/balloon: Initializing Xen " | |
521 | "selfballooning driver.\n"); | |
522 | enable = true; | |
523 | } | |
524 | #ifdef CONFIG_FRONTSWAP | |
525 | frontswap_selfshrinking = tmem_enabled && use_frontswap_selfshrink; | |
526 | if (frontswap_selfshrinking) { | |
527 | pr_info("xen/balloon: Initializing frontswap " | |
528 | "selfshrinking driver.\n"); | |
529 | enable = true; | |
530 | } | |
531 | #endif | |
532 | if (!enable) | |
533 | return -ENODEV; | |
534 | ||
535 | schedule_delayed_work(&selfballoon_worker, selfballoon_interval * HZ); | |
536 | ||
537 | return 0; | |
538 | } | |
10a7a077 | 539 | EXPORT_SYMBOL(xen_selfballoon_init); |