Contents of /trunk/kernel26-magellan/patches-2.6.16-r12/0019-2.6.16-mm-swap_prefetch-30.patch
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Revision 72 -
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Mon Jun 5 09:25:38 2006 UTC (18 years, 3 months ago) by niro
File size: 28305 byte(s)
Mon Jun 5 09:25:38 2006 UTC (18 years, 3 months ago) by niro
File size: 28305 byte(s)
ver bump to 2.6.16-r12: - updated to linux-2.6.16.19 - updated to ck11
1 | Documentation/sysctl/vm.txt | 11 |
2 | include/linux/mm_inline.h | 7 |
3 | include/linux/swap-prefetch.h | 55 ++++ |
4 | include/linux/swap.h | 2 |
5 | include/linux/sysctl.h | 1 |
6 | init/Kconfig | 22 + |
7 | kernel/sysctl.c | 11 |
8 | mm/Makefile | 1 |
9 | mm/swap.c | 44 +++ |
10 | mm/swap_prefetch.c | 574 ++++++++++++++++++++++++++++++++++++++++++ |
11 | mm/swap_state.c | 11 |
12 | mm/vmscan.c | 6 |
13 | 12 files changed, 744 insertions(+), 1 deletion(-) |
14 | |
15 | Index: linux-2.6.16-ck1/Documentation/sysctl/vm.txt |
16 | =================================================================== |
17 | --- linux-2.6.16-ck1.orig/Documentation/sysctl/vm.txt 2006-03-20 20:46:24.000000000 +1100 |
18 | +++ linux-2.6.16-ck1/Documentation/sysctl/vm.txt 2006-03-20 20:46:55.000000000 +1100 |
19 | @@ -29,6 +29,7 @@ Currently, these files are in /proc/sys/ |
20 | - drop-caches |
21 | - zone_reclaim_mode |
22 | - zone_reclaim_interval |
23 | +- swap_prefetch |
24 | |
25 | ============================================================== |
26 | |
27 | @@ -178,3 +179,13 @@ Time is set in seconds and set by defaul |
28 | Reduce the interval if undesired off node allocations occur. However, too |
29 | frequent scans will have a negative impact onoff node allocation performance. |
30 | |
31 | +============================================================== |
32 | + |
33 | +swap_prefetch |
34 | + |
35 | +This enables or disables the swap prefetching feature. When the virtual |
36 | +memory subsystem has been extremely idle for at least 5 seconds it will start |
37 | +copying back pages from swap into the swapcache and keep a copy in swap. In |
38 | +practice it can take many minutes before the vm is idle enough. |
39 | + |
40 | +The default value is 1. |
41 | Index: linux-2.6.16-ck1/include/linux/swap.h |
42 | =================================================================== |
43 | --- linux-2.6.16-ck1.orig/include/linux/swap.h 2006-03-20 20:46:24.000000000 +1100 |
44 | +++ linux-2.6.16-ck1/include/linux/swap.h 2006-03-20 20:46:55.000000000 +1100 |
45 | @@ -164,6 +164,7 @@ extern unsigned int nr_free_pagecache_pa |
46 | /* linux/mm/swap.c */ |
47 | extern void FASTCALL(lru_cache_add(struct page *)); |
48 | extern void FASTCALL(lru_cache_add_active(struct page *)); |
49 | +extern void FASTCALL(lru_cache_add_tail(struct page *)); |
50 | extern void FASTCALL(activate_page(struct page *)); |
51 | extern void FASTCALL(mark_page_accessed(struct page *)); |
52 | extern void lru_add_drain(void); |
53 | @@ -235,6 +236,7 @@ extern void free_pages_and_swap_cache(st |
54 | extern struct page * lookup_swap_cache(swp_entry_t); |
55 | extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma, |
56 | unsigned long addr); |
57 | +extern int add_to_swap_cache(struct page *page, swp_entry_t entry); |
58 | /* linux/mm/swapfile.c */ |
59 | extern long total_swap_pages; |
60 | extern unsigned int nr_swapfiles; |
61 | Index: linux-2.6.16-ck1/include/linux/sysctl.h |
62 | =================================================================== |
63 | --- linux-2.6.16-ck1.orig/include/linux/sysctl.h 2006-03-20 20:46:50.000000000 +1100 |
64 | +++ linux-2.6.16-ck1/include/linux/sysctl.h 2006-03-20 20:46:55.000000000 +1100 |
65 | @@ -189,6 +189,7 @@ enum |
66 | VM_PERCPU_PAGELIST_FRACTION=30,/* int: fraction of pages in each percpu_pagelist */ |
67 | VM_ZONE_RECLAIM_MODE=31, /* reclaim local zone memory before going off node */ |
68 | VM_ZONE_RECLAIM_INTERVAL=32, /* time period to wait after reclaim failure */ |
69 | + VM_SWAP_PREFETCH=33, /* swap prefetch */ |
70 | }; |
71 | |
72 | |
73 | Index: linux-2.6.16-ck1/init/Kconfig |
74 | =================================================================== |
75 | --- linux-2.6.16-ck1.orig/init/Kconfig 2006-03-20 20:46:24.000000000 +1100 |
76 | +++ linux-2.6.16-ck1/init/Kconfig 2006-03-20 20:46:55.000000000 +1100 |
77 | @@ -92,6 +92,28 @@ config SWAP |
78 | used to provide more virtual memory than the actual RAM present |
79 | in your computer. If unsure say Y. |
80 | |
81 | +config SWAP_PREFETCH |
82 | + bool "Support for prefetching swapped memory" |
83 | + depends on SWAP |
84 | + default y |
85 | + ---help--- |
86 | + This option will allow the kernel to prefetch swapped memory pages |
87 | + when idle. The pages will be kept on both swap and in swap_cache |
88 | + thus avoiding the need for further I/O if either ram or swap space |
89 | + is required. |
90 | + |
91 | + What this will do on workstations is slowly bring back applications |
92 | + that have swapped out after memory intensive workloads back into |
93 | + physical ram if you have free ram at a later stage and the machine |
94 | + is relatively idle. This means that when you come back to your |
95 | + computer after leaving it idle for a while, applications will come |
96 | + to life faster. Note that your swap usage will appear to increase |
97 | + but these are cached pages, can be dropped freely by the vm, and it |
98 | + should stabilise around 50% swap usage maximum. |
99 | + |
100 | + Workstations and multiuser workstation servers will most likely want |
101 | + to say Y. |
102 | + |
103 | config SYSVIPC |
104 | bool "System V IPC" |
105 | ---help--- |
106 | Index: linux-2.6.16-ck1/kernel/sysctl.c |
107 | =================================================================== |
108 | --- linux-2.6.16-ck1.orig/kernel/sysctl.c 2006-03-20 20:46:50.000000000 +1100 |
109 | +++ linux-2.6.16-ck1/kernel/sysctl.c 2006-03-20 20:46:55.000000000 +1100 |
110 | @@ -23,6 +23,7 @@ |
111 | #include <linux/mm.h> |
112 | #include <linux/swap.h> |
113 | #include <linux/slab.h> |
114 | +#include <linux/swap-prefetch.h> |
115 | #include <linux/sysctl.h> |
116 | #include <linux/proc_fs.h> |
117 | #include <linux/capability.h> |
118 | @@ -942,6 +943,16 @@ static ctl_table vm_table[] = { |
119 | .strategy = &sysctl_jiffies, |
120 | }, |
121 | #endif |
122 | +#ifdef CONFIG_SWAP_PREFETCH |
123 | + { |
124 | + .ctl_name = VM_SWAP_PREFETCH, |
125 | + .procname = "swap_prefetch", |
126 | + .data = &swap_prefetch, |
127 | + .maxlen = sizeof(swap_prefetch), |
128 | + .mode = 0644, |
129 | + .proc_handler = &proc_dointvec, |
130 | + }, |
131 | +#endif |
132 | { .ctl_name = 0 } |
133 | }; |
134 | |
135 | Index: linux-2.6.16-ck1/mm/Makefile |
136 | =================================================================== |
137 | --- linux-2.6.16-ck1.orig/mm/Makefile 2006-03-20 20:46:24.000000000 +1100 |
138 | +++ linux-2.6.16-ck1/mm/Makefile 2006-03-20 20:46:55.000000000 +1100 |
139 | @@ -13,6 +13,7 @@ obj-y := bootmem.o filemap.o mempool.o |
140 | prio_tree.o util.o $(mmu-y) |
141 | |
142 | obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o thrash.o |
143 | +obj-$(CONFIG_SWAP_PREFETCH) += swap_prefetch.o |
144 | obj-$(CONFIG_HUGETLBFS) += hugetlb.o |
145 | obj-$(CONFIG_NUMA) += mempolicy.o |
146 | obj-$(CONFIG_SPARSEMEM) += sparse.o |
147 | Index: linux-2.6.16-ck1/mm/swap.c |
148 | =================================================================== |
149 | --- linux-2.6.16-ck1.orig/mm/swap.c 2006-03-20 20:46:24.000000000 +1100 |
150 | +++ linux-2.6.16-ck1/mm/swap.c 2006-03-20 20:46:55.000000000 +1100 |
151 | @@ -17,6 +17,7 @@ |
152 | #include <linux/sched.h> |
153 | #include <linux/kernel_stat.h> |
154 | #include <linux/swap.h> |
155 | +#include <linux/swap-prefetch.h> |
156 | #include <linux/mman.h> |
157 | #include <linux/pagemap.h> |
158 | #include <linux/pagevec.h> |
159 | @@ -382,6 +383,46 @@ void __pagevec_lru_add_active(struct pag |
160 | pagevec_reinit(pvec); |
161 | } |
162 | |
163 | +static inline void __pagevec_lru_add_tail(struct pagevec *pvec) |
164 | +{ |
165 | + int i; |
166 | + struct zone *zone = NULL; |
167 | + |
168 | + for (i = 0; i < pagevec_count(pvec); i++) { |
169 | + struct page *page = pvec->pages[i]; |
170 | + struct zone *pagezone = page_zone(page); |
171 | + |
172 | + if (pagezone != zone) { |
173 | + if (zone) |
174 | + spin_unlock_irq(&zone->lru_lock); |
175 | + zone = pagezone; |
176 | + spin_lock_irq(&zone->lru_lock); |
177 | + } |
178 | + BUG_ON(PageLRU(page)); |
179 | + SetPageLRU(page); |
180 | + add_page_to_inactive_list_tail(zone, page); |
181 | + } |
182 | + if (zone) |
183 | + spin_unlock_irq(&zone->lru_lock); |
184 | + release_pages(pvec->pages, pvec->nr, pvec->cold); |
185 | + pagevec_reinit(pvec); |
186 | +} |
187 | + |
188 | +/* |
189 | + * Function used uniquely to put pages back to the lru at the end of the |
190 | + * inactive list to preserve the lru order. Currently only used by swap |
191 | + * prefetch. |
192 | + */ |
193 | +void fastcall lru_cache_add_tail(struct page *page) |
194 | +{ |
195 | + struct pagevec *pvec = &get_cpu_var(lru_add_pvecs); |
196 | + |
197 | + page_cache_get(page); |
198 | + if (!pagevec_add(pvec, page)) |
199 | + __pagevec_lru_add_tail(pvec); |
200 | + put_cpu_var(lru_add_pvecs); |
201 | +} |
202 | + |
203 | /* |
204 | * Try to drop buffers from the pages in a pagevec |
205 | */ |
206 | @@ -536,5 +577,8 @@ void __init swap_setup(void) |
207 | * Right now other parts of the system means that we |
208 | * _really_ don't want to cluster much more |
209 | */ |
210 | + |
211 | + prepare_swap_prefetch(); |
212 | + |
213 | hotcpu_notifier(cpu_swap_callback, 0); |
214 | } |
215 | Index: linux-2.6.16-ck1/mm/swap_prefetch.c |
216 | =================================================================== |
217 | --- /dev/null 1970-01-01 00:00:00.000000000 +0000 |
218 | +++ linux-2.6.16-ck1/mm/swap_prefetch.c 2006-03-20 20:46:55.000000000 +1100 |
219 | @@ -0,0 +1,574 @@ |
220 | +/* |
221 | + * linux/mm/swap_prefetch.c |
222 | + * |
223 | + * Copyright (C) 2005-2006 Con Kolivas |
224 | + * |
225 | + * Written by Con Kolivas <kernel@kolivas.org> |
226 | + * |
227 | + * This program is free software; you can redistribute it and/or modify |
228 | + * it under the terms of the GNU General Public License version 2 as |
229 | + * published by the Free Software Foundation. |
230 | + */ |
231 | + |
232 | +#include <linux/fs.h> |
233 | +#include <linux/mm.h> |
234 | +#include <linux/swap.h> |
235 | +#include <linux/swap-prefetch.h> |
236 | +#include <linux/ioprio.h> |
237 | +#include <linux/kthread.h> |
238 | +#include <linux/pagemap.h> |
239 | +#include <linux/syscalls.h> |
240 | +#include <linux/writeback.h> |
241 | + |
242 | +/* |
243 | + * Time to delay prefetching if vm is busy or prefetching unsuccessful. There |
244 | + * needs to be at least this duration of idle time meaning in practice it can |
245 | + * be much longer |
246 | + */ |
247 | +#define PREFETCH_DELAY (HZ * 5) |
248 | + |
249 | +/* sysctl - enable/disable swap prefetching */ |
250 | +int swap_prefetch __read_mostly = 1; |
251 | + |
252 | +struct swapped_root { |
253 | + unsigned long busy; /* vm busy */ |
254 | + spinlock_t lock; /* protects all data */ |
255 | + struct list_head list; /* MRU list of swapped pages */ |
256 | + struct radix_tree_root swap_tree; /* Lookup tree of pages */ |
257 | + unsigned int count; /* Number of entries */ |
258 | + unsigned int maxcount; /* Maximum entries allowed */ |
259 | + kmem_cache_t *cache; /* Of struct swapped_entry */ |
260 | +}; |
261 | + |
262 | +static struct swapped_root swapped = { |
263 | + .lock = SPIN_LOCK_UNLOCKED, |
264 | + .list = LIST_HEAD_INIT(swapped.list), |
265 | + .swap_tree = RADIX_TREE_INIT(GFP_ATOMIC), |
266 | +}; |
267 | + |
268 | +static task_t *kprefetchd_task; |
269 | + |
270 | +/* |
271 | + * We check to see no part of the vm is busy. If it is this will interrupt |
272 | + * trickle_swap and wait another PREFETCH_DELAY. Purposefully racy. |
273 | + */ |
274 | +inline void delay_swap_prefetch(void) |
275 | +{ |
276 | + if (!test_bit(0, &swapped.busy)) |
277 | + __set_bit(0, &swapped.busy); |
278 | +} |
279 | + |
280 | +/* |
281 | + * Drop behind accounting which keeps a list of the most recently used swap |
282 | + * entries. |
283 | + */ |
284 | +void add_to_swapped_list(struct page *page) |
285 | +{ |
286 | + struct swapped_entry *entry; |
287 | + unsigned long index; |
288 | + int wakeup; |
289 | + |
290 | + if (!swap_prefetch) |
291 | + return; |
292 | + |
293 | + wakeup = 0; |
294 | + |
295 | + spin_lock(&swapped.lock); |
296 | + if (swapped.count >= swapped.maxcount) { |
297 | + /* |
298 | + * We limit the number of entries to 2/3 of physical ram. |
299 | + * Once the number of entries exceeds this we start removing |
300 | + * the least recently used entries. |
301 | + */ |
302 | + entry = list_entry(swapped.list.next, |
303 | + struct swapped_entry, swapped_list); |
304 | + radix_tree_delete(&swapped.swap_tree, entry->swp_entry.val); |
305 | + list_del(&entry->swapped_list); |
306 | + swapped.count--; |
307 | + } else { |
308 | + entry = kmem_cache_alloc(swapped.cache, GFP_ATOMIC); |
309 | + if (unlikely(!entry)) |
310 | + /* bad, can't allocate more mem */ |
311 | + goto out_locked; |
312 | + } |
313 | + |
314 | + index = page_private(page); |
315 | + entry->swp_entry.val = index; |
316 | + /* |
317 | + * On numa we need to store the node id to ensure that we prefetch to |
318 | + * the same node it came from. |
319 | + */ |
320 | + store_swap_entry_node(entry, page); |
321 | + |
322 | + if (likely(!radix_tree_insert(&swapped.swap_tree, index, entry))) { |
323 | + /* |
324 | + * If this is the first entry, kprefetchd needs to be |
325 | + * (re)started. |
326 | + */ |
327 | + if (!swapped.count) |
328 | + wakeup = 1; |
329 | + list_add(&entry->swapped_list, &swapped.list); |
330 | + swapped.count++; |
331 | + } |
332 | + |
333 | +out_locked: |
334 | + spin_unlock(&swapped.lock); |
335 | + |
336 | + /* Do the wakeup outside the lock to shorten lock hold time. */ |
337 | + if (wakeup) |
338 | + wake_up_process(kprefetchd_task); |
339 | + |
340 | + return; |
341 | +} |
342 | + |
343 | +/* |
344 | + * Removes entries from the swapped_list. The radix tree allows us to quickly |
345 | + * look up the entry from the index without having to iterate over the whole |
346 | + * list. |
347 | + */ |
348 | +void remove_from_swapped_list(const unsigned long index) |
349 | +{ |
350 | + struct swapped_entry *entry; |
351 | + unsigned long flags; |
352 | + |
353 | + if (list_empty(&swapped.list)) |
354 | + return; |
355 | + |
356 | + spin_lock_irqsave(&swapped.lock, flags); |
357 | + entry = radix_tree_delete(&swapped.swap_tree, index); |
358 | + if (likely(entry)) { |
359 | + list_del_init(&entry->swapped_list); |
360 | + swapped.count--; |
361 | + kmem_cache_free(swapped.cache, entry); |
362 | + } |
363 | + spin_unlock_irqrestore(&swapped.lock, flags); |
364 | +} |
365 | + |
366 | +enum trickle_return { |
367 | + TRICKLE_SUCCESS, |
368 | + TRICKLE_FAILED, |
369 | + TRICKLE_DELAY, |
370 | +}; |
371 | + |
372 | +struct node_stats { |
373 | + unsigned long last_free; |
374 | + /* Free ram after a cycle of prefetching */ |
375 | + unsigned long current_free; |
376 | + /* Free ram on this cycle of checking prefetch_suitable */ |
377 | + unsigned long prefetch_watermark; |
378 | + /* Maximum amount we will prefetch to */ |
379 | + unsigned long highfree[MAX_NR_ZONES]; |
380 | + /* The amount of free ram before we start prefetching */ |
381 | + unsigned long lowfree[MAX_NR_ZONES]; |
382 | + /* The amount of free ram where we will stop prefetching */ |
383 | + unsigned long *pointfree[MAX_NR_ZONES]; |
384 | + /* highfree or lowfree depending on whether we've hit a watermark */ |
385 | +}; |
386 | + |
387 | +/* |
388 | + * prefetch_stats stores the free ram data of each node and this is used to |
389 | + * determine if a node is suitable for prefetching into. |
390 | + */ |
391 | +struct prefetch_stats { |
392 | + nodemask_t prefetch_nodes; |
393 | + /* Which nodes are currently suited to prefetching */ |
394 | + unsigned long prefetched_pages; |
395 | + /* Total pages we've prefetched on this wakeup of kprefetchd */ |
396 | + struct node_stats node[MAX_NUMNODES]; |
397 | +}; |
398 | + |
399 | +static struct prefetch_stats sp_stat; |
400 | + |
401 | +/* |
402 | + * This tries to read a swp_entry_t into swap cache for swap prefetching. |
403 | + * If it returns TRICKLE_DELAY we should delay further prefetching. |
404 | + */ |
405 | +static enum trickle_return trickle_swap_cache_async(const swp_entry_t entry, |
406 | + const int node) |
407 | +{ |
408 | + enum trickle_return ret = TRICKLE_FAILED; |
409 | + struct page *page; |
410 | + |
411 | + read_lock_irq(&swapper_space.tree_lock); |
412 | + /* Entry may already exist */ |
413 | + page = radix_tree_lookup(&swapper_space.page_tree, entry.val); |
414 | + read_unlock_irq(&swapper_space.tree_lock); |
415 | + if (page) { |
416 | + remove_from_swapped_list(entry.val); |
417 | + goto out; |
418 | + } |
419 | + |
420 | + /* |
421 | + * Get a new page to read from swap. We have already checked the |
422 | + * watermarks so __alloc_pages will not call on reclaim. |
423 | + */ |
424 | + page = alloc_pages_node(node, GFP_HIGHUSER & ~__GFP_WAIT, 0); |
425 | + if (unlikely(!page)) { |
426 | + ret = TRICKLE_DELAY; |
427 | + goto out; |
428 | + } |
429 | + |
430 | + if (add_to_swap_cache(page, entry)) { |
431 | + /* Failed to add to swap cache */ |
432 | + goto out_release; |
433 | + } |
434 | + |
435 | + /* Add them to the tail of the inactive list to preserve LRU order */ |
436 | + lru_cache_add_tail(page); |
437 | + if (unlikely(swap_readpage(NULL, page))) { |
438 | + ret = TRICKLE_DELAY; |
439 | + goto out_release; |
440 | + } |
441 | + |
442 | + sp_stat.prefetched_pages++; |
443 | + sp_stat.node[node].last_free--; |
444 | + |
445 | + ret = TRICKLE_SUCCESS; |
446 | +out_release: |
447 | + page_cache_release(page); |
448 | +out: |
449 | + return ret; |
450 | +} |
451 | + |
452 | +static void clear_last_prefetch_free(void) |
453 | +{ |
454 | + int node; |
455 | + |
456 | + /* |
457 | + * Reset the nodes suitable for prefetching to all nodes. We could |
458 | + * update the data to take into account memory hotplug if desired.. |
459 | + */ |
460 | + sp_stat.prefetch_nodes = node_online_map; |
461 | + for_each_node_mask(node, sp_stat.prefetch_nodes) { |
462 | + struct node_stats *ns = &sp_stat.node[node]; |
463 | + |
464 | + ns->last_free = 0; |
465 | + } |
466 | +} |
467 | + |
468 | +static void clear_current_prefetch_free(void) |
469 | +{ |
470 | + int node; |
471 | + |
472 | + sp_stat.prefetch_nodes = node_online_map; |
473 | + for_each_node_mask(node, sp_stat.prefetch_nodes) { |
474 | + struct node_stats *ns = &sp_stat.node[node]; |
475 | + |
476 | + ns->current_free = 0; |
477 | + } |
478 | +} |
479 | + |
480 | +/* |
481 | + * This updates the high and low watermarks of amount of free ram in each |
482 | + * node used to start and stop prefetching. We prefetch from pages_high * 4 |
483 | + * down to pages_high * 3. |
484 | + */ |
485 | +static void examine_free_limits(void) |
486 | +{ |
487 | + struct zone *z; |
488 | + |
489 | + for_each_zone(z) { |
490 | + struct node_stats *ns; |
491 | + int idx; |
492 | + |
493 | + if (!populated_zone(z)) |
494 | + continue; |
495 | + |
496 | + ns = &sp_stat.node[z->zone_pgdat->node_id]; |
497 | + idx = zone_idx(z); |
498 | + ns->lowfree[idx] = z->pages_high * 3 + z->lowmem_reserve[idx]; |
499 | + ns->highfree[idx] = ns->lowfree[idx] + z->pages_high; |
500 | + |
501 | + if (z->free_pages > ns->highfree[idx]) { |
502 | + /* |
503 | + * We've gotten above the high watermark of free pages |
504 | + * so we can start prefetching till we get to the low |
505 | + * watermark. |
506 | + */ |
507 | + ns->pointfree[idx] = &ns->lowfree[idx]; |
508 | + } |
509 | + } |
510 | +} |
511 | + |
512 | +/* |
513 | + * We want to be absolutely certain it's ok to start prefetching. |
514 | + */ |
515 | +static int prefetch_suitable(void) |
516 | +{ |
517 | + unsigned long limit; |
518 | + struct zone *z; |
519 | + int node, ret = 0, test_pagestate = 0; |
520 | + |
521 | + /* Purposefully racy */ |
522 | + if (test_bit(0, &swapped.busy)) { |
523 | + __clear_bit(0, &swapped.busy); |
524 | + goto out; |
525 | + } |
526 | + |
527 | + /* |
528 | + * get_page_state and above_background_load are expensive so we only |
529 | + * perform them every SWAP_CLUSTER_MAX prefetched_pages. |
530 | + * We test to see if we're above_background_load as disk activity |
531 | + * even at low priority can cause interrupt induced scheduling |
532 | + * latencies. |
533 | + */ |
534 | + if (!(sp_stat.prefetched_pages % SWAP_CLUSTER_MAX)) { |
535 | + if (above_background_load()) |
536 | + goto out; |
537 | + test_pagestate = 1; |
538 | + } |
539 | + |
540 | + clear_current_prefetch_free(); |
541 | + |
542 | + /* |
543 | + * Have some hysteresis between where page reclaiming and prefetching |
544 | + * will occur to prevent ping-ponging between them. |
545 | + */ |
546 | + for_each_zone(z) { |
547 | + struct node_stats *ns; |
548 | + unsigned long free; |
549 | + int idx; |
550 | + |
551 | + if (!populated_zone(z)) |
552 | + continue; |
553 | + |
554 | + node = z->zone_pgdat->node_id; |
555 | + ns = &sp_stat.node[node]; |
556 | + idx = zone_idx(z); |
557 | + |
558 | + free = z->free_pages; |
559 | + if (free < *ns->pointfree[idx]) { |
560 | + /* |
561 | + * Free pages have dropped below the low watermark so |
562 | + * we won't start prefetching again till we hit the |
563 | + * high watermark of free pages. |
564 | + */ |
565 | + ns->pointfree[idx] = &ns->highfree[idx]; |
566 | + node_clear(node, sp_stat.prefetch_nodes); |
567 | + continue; |
568 | + } |
569 | + ns->current_free += free; |
570 | + } |
571 | + |
572 | + /* |
573 | + * We iterate over each node testing to see if it is suitable for |
574 | + * prefetching and clear the nodemask if it is not. |
575 | + */ |
576 | + for_each_node_mask(node, sp_stat.prefetch_nodes) { |
577 | + struct node_stats *ns = &sp_stat.node[node]; |
578 | + struct page_state ps; |
579 | + |
580 | + /* |
581 | + * We check to see that pages are not being allocated |
582 | + * elsewhere at any significant rate implying any |
583 | + * degree of memory pressure (eg during file reads) |
584 | + */ |
585 | + if (ns->last_free) { |
586 | + if (ns->current_free + SWAP_CLUSTER_MAX < |
587 | + ns->last_free) { |
588 | + ns->last_free = ns->current_free; |
589 | + node_clear(node, |
590 | + sp_stat.prefetch_nodes); |
591 | + continue; |
592 | + } |
593 | + } else |
594 | + ns->last_free = ns->current_free; |
595 | + |
596 | + if (!test_pagestate) |
597 | + continue; |
598 | + |
599 | + get_page_state_node(&ps, node); |
600 | + |
601 | + /* We shouldn't prefetch when we are doing writeback */ |
602 | + if (ps.nr_writeback) { |
603 | + node_clear(node, sp_stat.prefetch_nodes); |
604 | + continue; |
605 | + } |
606 | + |
607 | + /* |
608 | + * >2/3 of the ram on this node is mapped, slab, swapcache or |
609 | + * dirty, we need to leave some free for pagecache. |
610 | + * Note that currently nr_slab is innacurate on numa because |
611 | + * nr_slab is incremented on the node doing the accounting |
612 | + * even if the slab is being allocated on a remote node. This |
613 | + * would be expensive to fix and not of great significance. |
614 | + */ |
615 | + limit = ps.nr_mapped + ps.nr_slab + ps.nr_dirty + |
616 | + ps.nr_unstable + total_swapcache_pages; |
617 | + if (limit > ns->prefetch_watermark) { |
618 | + node_clear(node, sp_stat.prefetch_nodes); |
619 | + continue; |
620 | + } |
621 | + } |
622 | + |
623 | + if (nodes_empty(sp_stat.prefetch_nodes)) |
624 | + goto out; |
625 | + |
626 | + /* Survived all that? Hooray we can prefetch! */ |
627 | + ret = 1; |
628 | +out: |
629 | + return ret; |
630 | +} |
631 | + |
632 | +/* |
633 | + * Get previous swapped entry when iterating over all entries. swapped.lock |
634 | + * should be held and we should already ensure that entry exists. |
635 | + */ |
636 | +static inline struct swapped_entry *prev_swapped_entry |
637 | + (struct swapped_entry *entry) |
638 | +{ |
639 | + return list_entry(entry->swapped_list.prev->prev, |
640 | + struct swapped_entry, swapped_list); |
641 | +} |
642 | + |
643 | +/* |
644 | + * trickle_swap is the main function that initiates the swap prefetching. It |
645 | + * first checks to see if the busy flag is set, and does not prefetch if it |
646 | + * is, as the flag implied we are low on memory or swapping in currently. |
647 | + * Otherwise it runs until prefetch_suitable fails which occurs when the |
648 | + * vm is busy, we prefetch to the watermark, or the list is empty or we have |
649 | + * iterated over all entries |
650 | + */ |
651 | +static enum trickle_return trickle_swap(void) |
652 | +{ |
653 | + enum trickle_return ret = TRICKLE_DELAY; |
654 | + struct swapped_entry *entry; |
655 | + |
656 | + /* |
657 | + * If laptop_mode is enabled don't prefetch to avoid hard drives |
658 | + * doing unnecessary spin-ups |
659 | + */ |
660 | + if (!swap_prefetch || laptop_mode) |
661 | + return ret; |
662 | + |
663 | + examine_free_limits(); |
664 | + entry = NULL; |
665 | + |
666 | + for ( ; ; ) { |
667 | + swp_entry_t swp_entry; |
668 | + int node; |
669 | + |
670 | + if (!prefetch_suitable()) |
671 | + break; |
672 | + |
673 | + spin_lock(&swapped.lock); |
674 | + if (list_empty(&swapped.list)) { |
675 | + ret = TRICKLE_FAILED; |
676 | + spin_unlock(&swapped.lock); |
677 | + break; |
678 | + } |
679 | + |
680 | + if (!entry) { |
681 | + /* |
682 | + * This sets the entry for the first iteration. It |
683 | + * also is a safeguard against the entry disappearing |
684 | + * while the lock is not held. |
685 | + */ |
686 | + entry = list_entry(swapped.list.prev, |
687 | + struct swapped_entry, swapped_list); |
688 | + } else if (entry->swapped_list.prev == swapped.list.next) { |
689 | + /* |
690 | + * If we have iterated over all entries and there are |
691 | + * still entries that weren't swapped out there may |
692 | + * be a reason we could not swap them back in so |
693 | + * delay attempting further prefetching. |
694 | + */ |
695 | + spin_unlock(&swapped.lock); |
696 | + break; |
697 | + } |
698 | + |
699 | + node = get_swap_entry_node(entry); |
700 | + if (!node_isset(node, sp_stat.prefetch_nodes)) { |
701 | + /* |
702 | + * We found an entry that belongs to a node that is |
703 | + * not suitable for prefetching so skip it. |
704 | + */ |
705 | + entry = prev_swapped_entry(entry); |
706 | + spin_unlock(&swapped.lock); |
707 | + continue; |
708 | + } |
709 | + swp_entry = entry->swp_entry; |
710 | + entry = prev_swapped_entry(entry); |
711 | + spin_unlock(&swapped.lock); |
712 | + |
713 | + if (trickle_swap_cache_async(swp_entry, node) == TRICKLE_DELAY) |
714 | + break; |
715 | + } |
716 | + |
717 | + if (sp_stat.prefetched_pages) { |
718 | + lru_add_drain(); |
719 | + sp_stat.prefetched_pages = 0; |
720 | + } |
721 | + return ret; |
722 | +} |
723 | + |
724 | +static int kprefetchd(void *__unused) |
725 | +{ |
726 | + set_user_nice(current, 19); |
727 | + /* Set ioprio to lowest if supported by i/o scheduler */ |
728 | + sys_ioprio_set(IOPRIO_WHO_PROCESS, 0, IOPRIO_CLASS_IDLE); |
729 | + |
730 | + do { |
731 | + try_to_freeze(); |
732 | + |
733 | + /* |
734 | + * TRICKLE_FAILED implies no entries left - we do not schedule |
735 | + * a wakeup, and further delay the next one. |
736 | + */ |
737 | + if (trickle_swap() == TRICKLE_FAILED) { |
738 | + set_current_state(TASK_INTERRUPTIBLE); |
739 | + schedule(); |
740 | + } |
741 | + clear_last_prefetch_free(); |
742 | + schedule_timeout_interruptible(PREFETCH_DELAY); |
743 | + } while (!kthread_should_stop()); |
744 | + |
745 | + return 0; |
746 | +} |
747 | + |
748 | +/* |
749 | + * Create kmem cache for swapped entries |
750 | + */ |
751 | +void __init prepare_swap_prefetch(void) |
752 | +{ |
753 | + struct zone *zone; |
754 | + |
755 | + swapped.cache = kmem_cache_create("swapped_entry", |
756 | + sizeof(struct swapped_entry), 0, SLAB_PANIC, NULL, NULL); |
757 | + |
758 | + /* |
759 | + * Set max number of entries to 2/3 the size of physical ram as we |
760 | + * only ever prefetch to consume 2/3 of the ram. |
761 | + */ |
762 | + swapped.maxcount = nr_free_pagecache_pages() / 3 * 2; |
763 | + |
764 | + for_each_zone(zone) { |
765 | + unsigned long present; |
766 | + struct node_stats *ns; |
767 | + int idx; |
768 | + |
769 | + present = zone->present_pages; |
770 | + if (!present) |
771 | + continue; |
772 | + |
773 | + ns = &sp_stat.node[zone->zone_pgdat->node_id]; |
774 | + ns->prefetch_watermark += present / 3 * 2; |
775 | + idx = zone_idx(zone); |
776 | + ns->pointfree[idx] = &ns->highfree[idx]; |
777 | + } |
778 | +} |
779 | + |
780 | +static int __init kprefetchd_init(void) |
781 | +{ |
782 | + kprefetchd_task = kthread_run(kprefetchd, NULL, "kprefetchd"); |
783 | + |
784 | + return 0; |
785 | +} |
786 | + |
787 | +static void __exit kprefetchd_exit(void) |
788 | +{ |
789 | + kthread_stop(kprefetchd_task); |
790 | +} |
791 | + |
792 | +module_init(kprefetchd_init); |
793 | +module_exit(kprefetchd_exit); |
794 | Index: linux-2.6.16-ck1/mm/swap_state.c |
795 | =================================================================== |
796 | --- linux-2.6.16-ck1.orig/mm/swap_state.c 2006-03-20 20:46:24.000000000 +1100 |
797 | +++ linux-2.6.16-ck1/mm/swap_state.c 2006-03-20 20:46:55.000000000 +1100 |
798 | @@ -10,6 +10,7 @@ |
799 | #include <linux/mm.h> |
800 | #include <linux/kernel_stat.h> |
801 | #include <linux/swap.h> |
802 | +#include <linux/swap-prefetch.h> |
803 | #include <linux/init.h> |
804 | #include <linux/pagemap.h> |
805 | #include <linux/buffer_head.h> |
806 | @@ -81,6 +82,7 @@ static int __add_to_swap_cache(struct pa |
807 | error = radix_tree_insert(&swapper_space.page_tree, |
808 | entry.val, page); |
809 | if (!error) { |
810 | + remove_from_swapped_list(entry.val); |
811 | page_cache_get(page); |
812 | SetPageLocked(page); |
813 | SetPageSwapCache(page); |
814 | @@ -94,11 +96,12 @@ static int __add_to_swap_cache(struct pa |
815 | return error; |
816 | } |
817 | |
818 | -static int add_to_swap_cache(struct page *page, swp_entry_t entry) |
819 | +int add_to_swap_cache(struct page *page, swp_entry_t entry) |
820 | { |
821 | int error; |
822 | |
823 | if (!swap_duplicate(entry)) { |
824 | + remove_from_swapped_list(entry.val); |
825 | INC_CACHE_INFO(noent_race); |
826 | return -ENOENT; |
827 | } |
828 | @@ -147,6 +150,9 @@ int add_to_swap(struct page * page, gfp_ |
829 | swp_entry_t entry; |
830 | int err; |
831 | |
832 | + /* Swap prefetching is delayed if we're swapping pages */ |
833 | + delay_swap_prefetch(); |
834 | + |
835 | if (!PageLocked(page)) |
836 | BUG(); |
837 | |
838 | @@ -320,6 +326,9 @@ struct page *read_swap_cache_async(swp_e |
839 | struct page *found_page, *new_page = NULL; |
840 | int err; |
841 | |
842 | + /* Swap prefetching is delayed if we're already reading from swap */ |
843 | + delay_swap_prefetch(); |
844 | + |
845 | do { |
846 | /* |
847 | * First check the swap cache. Since this is normally |
848 | Index: linux-2.6.16-ck1/mm/vmscan.c |
849 | =================================================================== |
850 | --- linux-2.6.16-ck1.orig/mm/vmscan.c 2006-03-20 20:46:24.000000000 +1100 |
851 | +++ linux-2.6.16-ck1/mm/vmscan.c 2006-03-20 20:46:55.000000000 +1100 |
852 | @@ -16,6 +16,7 @@ |
853 | #include <linux/slab.h> |
854 | #include <linux/kernel_stat.h> |
855 | #include <linux/swap.h> |
856 | +#include <linux/swap-prefetch.h> |
857 | #include <linux/pagemap.h> |
858 | #include <linux/init.h> |
859 | #include <linux/highmem.h> |
860 | @@ -396,6 +397,7 @@ static int remove_mapping(struct address |
861 | |
862 | if (PageSwapCache(page)) { |
863 | swp_entry_t swap = { .val = page_private(page) }; |
864 | + add_to_swapped_list(page); |
865 | __delete_from_swap_cache(page); |
866 | write_unlock_irq(&mapping->tree_lock); |
867 | swap_free(swap); |
868 | @@ -1442,6 +1444,8 @@ int try_to_free_pages(struct zone **zone |
869 | sc.may_writepage = !laptop_mode; |
870 | sc.may_swap = 1; |
871 | |
872 | + delay_swap_prefetch(); |
873 | + |
874 | inc_page_state(allocstall); |
875 | |
876 | for (i = 0; zones[i] != NULL; i++) { |
877 | @@ -1788,6 +1792,8 @@ int shrink_all_memory(int nr_pages) |
878 | .reclaimed_slab = 0, |
879 | }; |
880 | |
881 | + delay_swap_prefetch(); |
882 | + |
883 | current->reclaim_state = &reclaim_state; |
884 | for_each_pgdat(pgdat) { |
885 | int freed; |
886 | Index: linux-2.6.16-ck1/include/linux/mm_inline.h |
887 | =================================================================== |
888 | --- linux-2.6.16-ck1.orig/include/linux/mm_inline.h 2006-03-20 20:46:24.000000000 +1100 |
889 | +++ linux-2.6.16-ck1/include/linux/mm_inline.h 2006-03-20 20:46:55.000000000 +1100 |
890 | @@ -14,6 +14,13 @@ add_page_to_inactive_list(struct zone *z |
891 | } |
892 | |
893 | static inline void |
894 | +add_page_to_inactive_list_tail(struct zone *zone, struct page *page) |
895 | +{ |
896 | + list_add_tail(&page->lru, &zone->inactive_list); |
897 | + zone->nr_inactive++; |
898 | +} |
899 | + |
900 | +static inline void |
901 | del_page_from_active_list(struct zone *zone, struct page *page) |
902 | { |
903 | list_del(&page->lru); |
904 | Index: linux-2.6.16-ck1/include/linux/swap-prefetch.h |
905 | =================================================================== |
906 | --- /dev/null 1970-01-01 00:00:00.000000000 +0000 |
907 | +++ linux-2.6.16-ck1/include/linux/swap-prefetch.h 2006-03-20 20:46:55.000000000 +1100 |
908 | @@ -0,0 +1,55 @@ |
909 | +#ifndef SWAP_PREFETCH_H_INCLUDED |
910 | +#define SWAP_PREFETCH_H_INCLUDED |
911 | + |
912 | +#ifdef CONFIG_SWAP_PREFETCH |
913 | +/* mm/swap_prefetch.c */ |
914 | +extern int swap_prefetch; |
915 | +struct swapped_entry { |
916 | + swp_entry_t swp_entry; /* The actual swap entry */ |
917 | + struct list_head swapped_list; /* Linked list of entries */ |
918 | +#if MAX_NUMNODES > 1 |
919 | + int node; /* Node id */ |
920 | +#endif |
921 | +} __attribute__((packed)); |
922 | + |
923 | +static inline void store_swap_entry_node(struct swapped_entry *entry, |
924 | + struct page *page) |
925 | +{ |
926 | +#if MAX_NUMNODES > 1 |
927 | + entry->node = page_to_nid(page); |
928 | +#endif |
929 | +} |
930 | + |
931 | +static inline int get_swap_entry_node(struct swapped_entry *entry) |
932 | +{ |
933 | +#if MAX_NUMNODES > 1 |
934 | + return entry->node; |
935 | +#else |
936 | + return 0; |
937 | +#endif |
938 | +} |
939 | + |
940 | +extern void add_to_swapped_list(struct page *page); |
941 | +extern void remove_from_swapped_list(const unsigned long index); |
942 | +extern void delay_swap_prefetch(void); |
943 | +extern void prepare_swap_prefetch(void); |
944 | + |
945 | +#else /* CONFIG_SWAP_PREFETCH */ |
946 | +static inline void add_to_swapped_list(struct page *__unused) |
947 | +{ |
948 | +} |
949 | + |
950 | +static inline void prepare_swap_prefetch(void) |
951 | +{ |
952 | +} |
953 | + |
954 | +static inline void remove_from_swapped_list(const unsigned long __unused) |
955 | +{ |
956 | +} |
957 | + |
958 | +static inline void delay_swap_prefetch(void) |
959 | +{ |
960 | +} |
961 | +#endif /* CONFIG_SWAP_PREFETCH */ |
962 | + |
963 | +#endif /* SWAP_PREFETCH_H_INCLUDED */ |