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34dc7c2f BB |
1 | /* |
2 | * CDDL HEADER START | |
3 | * | |
4 | * The contents of this file are subject to the terms of the | |
5 | * Common Development and Distribution License (the "License"). | |
6 | * You may not use this file except in compliance with the License. | |
7 | * | |
8 | * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE | |
9 | * or http://www.opensolaris.org/os/licensing. | |
10 | * See the License for the specific language governing permissions | |
11 | * and limitations under the License. | |
12 | * | |
13 | * When distributing Covered Code, include this CDDL HEADER in each | |
14 | * file and include the License file at usr/src/OPENSOLARIS.LICENSE. | |
15 | * If applicable, add the following below this CDDL HEADER, with the | |
16 | * fields enclosed by brackets "[]" replaced with your own identifying | |
17 | * information: Portions Copyright [yyyy] [name of copyright owner] | |
18 | * | |
19 | * CDDL HEADER END | |
20 | */ | |
21 | /* | |
428870ff | 22 | * Copyright 2009 Sun Microsystems, Inc. All rights reserved. |
34dc7c2f BB |
23 | * Use is subject to license terms. |
24 | */ | |
25 | ||
34dc7c2f BB |
26 | #include <sys/zfs_context.h> |
27 | #include <sys/dnode.h> | |
28 | #include <sys/dmu_objset.h> | |
29 | #include <sys/dmu_zfetch.h> | |
30 | #include <sys/dmu.h> | |
31 | #include <sys/dbuf.h> | |
428870ff | 32 | #include <sys/kstat.h> |
34dc7c2f BB |
33 | |
34 | /* | |
35 | * I'm against tune-ables, but these should probably exist as tweakable globals | |
36 | * until we can get this working the way we want it to. | |
37 | */ | |
38 | ||
39 | int zfs_prefetch_disable = 0; | |
40 | ||
41 | /* max # of streams per zfetch */ | |
42 | uint32_t zfetch_max_streams = 8; | |
43 | /* min time before stream reclaim */ | |
44 | uint32_t zfetch_min_sec_reap = 2; | |
45 | /* max number of blocks to fetch at a time */ | |
46 | uint32_t zfetch_block_cap = 256; | |
47 | /* number of bytes in a array_read at which we stop prefetching (1Mb) */ | |
48 | uint64_t zfetch_array_rd_sz = 1024 * 1024; | |
49 | ||
50 | /* forward decls for static routines */ | |
51 | static int dmu_zfetch_colinear(zfetch_t *, zstream_t *); | |
52 | static void dmu_zfetch_dofetch(zfetch_t *, zstream_t *); | |
53 | static uint64_t dmu_zfetch_fetch(dnode_t *, uint64_t, uint64_t); | |
54 | static uint64_t dmu_zfetch_fetchsz(dnode_t *, uint64_t, uint64_t); | |
55 | static int dmu_zfetch_find(zfetch_t *, zstream_t *, int); | |
56 | static int dmu_zfetch_stream_insert(zfetch_t *, zstream_t *); | |
57 | static zstream_t *dmu_zfetch_stream_reclaim(zfetch_t *); | |
58 | static void dmu_zfetch_stream_remove(zfetch_t *, zstream_t *); | |
59 | static int dmu_zfetch_streams_equal(zstream_t *, zstream_t *); | |
60 | ||
428870ff BB |
61 | typedef struct zfetch_stats { |
62 | kstat_named_t zfetchstat_hits; | |
63 | kstat_named_t zfetchstat_misses; | |
64 | kstat_named_t zfetchstat_colinear_hits; | |
65 | kstat_named_t zfetchstat_colinear_misses; | |
66 | kstat_named_t zfetchstat_stride_hits; | |
67 | kstat_named_t zfetchstat_stride_misses; | |
68 | kstat_named_t zfetchstat_reclaim_successes; | |
69 | kstat_named_t zfetchstat_reclaim_failures; | |
70 | kstat_named_t zfetchstat_stream_resets; | |
71 | kstat_named_t zfetchstat_stream_noresets; | |
72 | kstat_named_t zfetchstat_bogus_streams; | |
73 | } zfetch_stats_t; | |
74 | ||
75 | static zfetch_stats_t zfetch_stats = { | |
76 | { "hits", KSTAT_DATA_UINT64 }, | |
77 | { "misses", KSTAT_DATA_UINT64 }, | |
78 | { "colinear_hits", KSTAT_DATA_UINT64 }, | |
79 | { "colinear_misses", KSTAT_DATA_UINT64 }, | |
80 | { "stride_hits", KSTAT_DATA_UINT64 }, | |
81 | { "stride_misses", KSTAT_DATA_UINT64 }, | |
82 | { "reclaim_successes", KSTAT_DATA_UINT64 }, | |
83 | { "reclaim_failures", KSTAT_DATA_UINT64 }, | |
84 | { "streams_resets", KSTAT_DATA_UINT64 }, | |
85 | { "streams_noresets", KSTAT_DATA_UINT64 }, | |
86 | { "bogus_streams", KSTAT_DATA_UINT64 }, | |
87 | }; | |
88 | ||
89 | #define ZFETCHSTAT_INCR(stat, val) \ | |
90 | atomic_add_64(&zfetch_stats.stat.value.ui64, (val)); | |
91 | ||
92 | #define ZFETCHSTAT_BUMP(stat) ZFETCHSTAT_INCR(stat, 1); | |
93 | ||
94 | kstat_t *zfetch_ksp; | |
95 | ||
34dc7c2f BB |
96 | /* |
97 | * Given a zfetch structure and a zstream structure, determine whether the | |
98 | * blocks to be read are part of a co-linear pair of existing prefetch | |
99 | * streams. If a set is found, coalesce the streams, removing one, and | |
100 | * configure the prefetch so it looks for a strided access pattern. | |
101 | * | |
102 | * In other words: if we find two sequential access streams that are | |
103 | * the same length and distance N appart, and this read is N from the | |
104 | * last stream, then we are probably in a strided access pattern. So | |
105 | * combine the two sequential streams into a single strided stream. | |
106 | * | |
107 | * If no co-linear streams are found, return NULL. | |
108 | */ | |
109 | static int | |
110 | dmu_zfetch_colinear(zfetch_t *zf, zstream_t *zh) | |
111 | { | |
112 | zstream_t *z_walk; | |
113 | zstream_t *z_comp; | |
114 | ||
115 | if (! rw_tryenter(&zf->zf_rwlock, RW_WRITER)) | |
116 | return (0); | |
117 | ||
118 | if (zh == NULL) { | |
119 | rw_exit(&zf->zf_rwlock); | |
120 | return (0); | |
121 | } | |
122 | ||
123 | for (z_walk = list_head(&zf->zf_stream); z_walk; | |
124 | z_walk = list_next(&zf->zf_stream, z_walk)) { | |
125 | for (z_comp = list_next(&zf->zf_stream, z_walk); z_comp; | |
126 | z_comp = list_next(&zf->zf_stream, z_comp)) { | |
127 | int64_t diff; | |
128 | ||
129 | if (z_walk->zst_len != z_walk->zst_stride || | |
130 | z_comp->zst_len != z_comp->zst_stride) { | |
131 | continue; | |
132 | } | |
133 | ||
134 | diff = z_comp->zst_offset - z_walk->zst_offset; | |
135 | if (z_comp->zst_offset + diff == zh->zst_offset) { | |
136 | z_walk->zst_offset = zh->zst_offset; | |
137 | z_walk->zst_direction = diff < 0 ? -1 : 1; | |
138 | z_walk->zst_stride = | |
139 | diff * z_walk->zst_direction; | |
140 | z_walk->zst_ph_offset = | |
141 | zh->zst_offset + z_walk->zst_stride; | |
142 | dmu_zfetch_stream_remove(zf, z_comp); | |
143 | mutex_destroy(&z_comp->zst_lock); | |
144 | kmem_free(z_comp, sizeof (zstream_t)); | |
145 | ||
146 | dmu_zfetch_dofetch(zf, z_walk); | |
147 | ||
148 | rw_exit(&zf->zf_rwlock); | |
149 | return (1); | |
150 | } | |
151 | ||
152 | diff = z_walk->zst_offset - z_comp->zst_offset; | |
153 | if (z_walk->zst_offset + diff == zh->zst_offset) { | |
154 | z_walk->zst_offset = zh->zst_offset; | |
155 | z_walk->zst_direction = diff < 0 ? -1 : 1; | |
156 | z_walk->zst_stride = | |
157 | diff * z_walk->zst_direction; | |
158 | z_walk->zst_ph_offset = | |
159 | zh->zst_offset + z_walk->zst_stride; | |
160 | dmu_zfetch_stream_remove(zf, z_comp); | |
161 | mutex_destroy(&z_comp->zst_lock); | |
162 | kmem_free(z_comp, sizeof (zstream_t)); | |
163 | ||
164 | dmu_zfetch_dofetch(zf, z_walk); | |
165 | ||
166 | rw_exit(&zf->zf_rwlock); | |
167 | return (1); | |
168 | } | |
169 | } | |
170 | } | |
171 | ||
172 | rw_exit(&zf->zf_rwlock); | |
173 | return (0); | |
174 | } | |
175 | ||
176 | /* | |
177 | * Given a zstream_t, determine the bounds of the prefetch. Then call the | |
178 | * routine that actually prefetches the individual blocks. | |
179 | */ | |
180 | static void | |
181 | dmu_zfetch_dofetch(zfetch_t *zf, zstream_t *zs) | |
182 | { | |
183 | uint64_t prefetch_tail; | |
184 | uint64_t prefetch_limit; | |
185 | uint64_t prefetch_ofst; | |
186 | uint64_t prefetch_len; | |
187 | uint64_t blocks_fetched; | |
188 | ||
189 | zs->zst_stride = MAX((int64_t)zs->zst_stride, zs->zst_len); | |
190 | zs->zst_cap = MIN(zfetch_block_cap, 2 * zs->zst_cap); | |
191 | ||
192 | prefetch_tail = MAX((int64_t)zs->zst_ph_offset, | |
193 | (int64_t)(zs->zst_offset + zs->zst_stride)); | |
194 | /* | |
195 | * XXX: use a faster division method? | |
196 | */ | |
197 | prefetch_limit = zs->zst_offset + zs->zst_len + | |
198 | (zs->zst_cap * zs->zst_stride) / zs->zst_len; | |
199 | ||
200 | while (prefetch_tail < prefetch_limit) { | |
201 | prefetch_ofst = zs->zst_offset + zs->zst_direction * | |
202 | (prefetch_tail - zs->zst_offset); | |
203 | ||
204 | prefetch_len = zs->zst_len; | |
205 | ||
206 | /* | |
207 | * Don't prefetch beyond the end of the file, if working | |
208 | * backwards. | |
209 | */ | |
210 | if ((zs->zst_direction == ZFETCH_BACKWARD) && | |
211 | (prefetch_ofst > prefetch_tail)) { | |
212 | prefetch_len += prefetch_ofst; | |
213 | prefetch_ofst = 0; | |
214 | } | |
215 | ||
216 | /* don't prefetch more than we're supposed to */ | |
217 | if (prefetch_len > zs->zst_len) | |
218 | break; | |
219 | ||
220 | blocks_fetched = dmu_zfetch_fetch(zf->zf_dnode, | |
221 | prefetch_ofst, zs->zst_len); | |
222 | ||
223 | prefetch_tail += zs->zst_stride; | |
224 | /* stop if we've run out of stuff to prefetch */ | |
225 | if (blocks_fetched < zs->zst_len) | |
226 | break; | |
227 | } | |
228 | zs->zst_ph_offset = prefetch_tail; | |
428870ff BB |
229 | zs->zst_last = ddi_get_lbolt(); |
230 | } | |
231 | ||
232 | void | |
233 | zfetch_init(void) | |
234 | { | |
235 | ||
236 | zfetch_ksp = kstat_create("zfs", 0, "zfetchstats", "misc", | |
237 | KSTAT_TYPE_NAMED, sizeof (zfetch_stats) / sizeof (kstat_named_t), | |
238 | KSTAT_FLAG_VIRTUAL); | |
239 | ||
240 | if (zfetch_ksp != NULL) { | |
241 | zfetch_ksp->ks_data = &zfetch_stats; | |
242 | kstat_install(zfetch_ksp); | |
243 | } | |
244 | } | |
245 | ||
246 | void | |
247 | zfetch_fini(void) | |
248 | { | |
249 | if (zfetch_ksp != NULL) { | |
250 | kstat_delete(zfetch_ksp); | |
251 | zfetch_ksp = NULL; | |
252 | } | |
34dc7c2f BB |
253 | } |
254 | ||
255 | /* | |
256 | * This takes a pointer to a zfetch structure and a dnode. It performs the | |
257 | * necessary setup for the zfetch structure, grokking data from the | |
258 | * associated dnode. | |
259 | */ | |
260 | void | |
261 | dmu_zfetch_init(zfetch_t *zf, dnode_t *dno) | |
262 | { | |
263 | if (zf == NULL) { | |
264 | return; | |
265 | } | |
266 | ||
267 | zf->zf_dnode = dno; | |
268 | zf->zf_stream_cnt = 0; | |
269 | zf->zf_alloc_fail = 0; | |
270 | ||
271 | list_create(&zf->zf_stream, sizeof (zstream_t), | |
272 | offsetof(zstream_t, zst_node)); | |
273 | ||
274 | rw_init(&zf->zf_rwlock, NULL, RW_DEFAULT, NULL); | |
275 | } | |
276 | ||
277 | /* | |
278 | * This function computes the actual size, in blocks, that can be prefetched, | |
279 | * and fetches it. | |
280 | */ | |
281 | static uint64_t | |
282 | dmu_zfetch_fetch(dnode_t *dn, uint64_t blkid, uint64_t nblks) | |
283 | { | |
284 | uint64_t fetchsz; | |
285 | uint64_t i; | |
286 | ||
287 | fetchsz = dmu_zfetch_fetchsz(dn, blkid, nblks); | |
288 | ||
289 | for (i = 0; i < fetchsz; i++) { | |
290 | dbuf_prefetch(dn, blkid + i); | |
291 | } | |
292 | ||
293 | return (fetchsz); | |
294 | } | |
295 | ||
296 | /* | |
297 | * this function returns the number of blocks that would be prefetched, based | |
298 | * upon the supplied dnode, blockid, and nblks. This is used so that we can | |
299 | * update streams in place, and then prefetch with their old value after the | |
300 | * fact. This way, we can delay the prefetch, but subsequent accesses to the | |
301 | * stream won't result in the same data being prefetched multiple times. | |
302 | */ | |
303 | static uint64_t | |
304 | dmu_zfetch_fetchsz(dnode_t *dn, uint64_t blkid, uint64_t nblks) | |
305 | { | |
306 | uint64_t fetchsz; | |
307 | ||
308 | if (blkid > dn->dn_maxblkid) { | |
309 | return (0); | |
310 | } | |
311 | ||
312 | /* compute fetch size */ | |
313 | if (blkid + nblks + 1 > dn->dn_maxblkid) { | |
314 | fetchsz = (dn->dn_maxblkid - blkid) + 1; | |
315 | ASSERT(blkid + fetchsz - 1 <= dn->dn_maxblkid); | |
316 | } else { | |
317 | fetchsz = nblks; | |
318 | } | |
319 | ||
320 | ||
321 | return (fetchsz); | |
322 | } | |
323 | ||
324 | /* | |
428870ff | 325 | * given a zfetch and a zstream structure, see if there is an associated zstream |
34dc7c2f BB |
326 | * for this block read. If so, it starts a prefetch for the stream it |
327 | * located and returns true, otherwise it returns false | |
328 | */ | |
329 | static int | |
330 | dmu_zfetch_find(zfetch_t *zf, zstream_t *zh, int prefetched) | |
331 | { | |
332 | zstream_t *zs; | |
333 | int64_t diff; | |
334 | int reset = !prefetched; | |
335 | int rc = 0; | |
336 | ||
337 | if (zh == NULL) | |
338 | return (0); | |
339 | ||
340 | /* | |
341 | * XXX: This locking strategy is a bit coarse; however, it's impact has | |
342 | * yet to be tested. If this turns out to be an issue, it can be | |
343 | * modified in a number of different ways. | |
344 | */ | |
345 | ||
346 | rw_enter(&zf->zf_rwlock, RW_READER); | |
347 | top: | |
348 | ||
349 | for (zs = list_head(&zf->zf_stream); zs; | |
350 | zs = list_next(&zf->zf_stream, zs)) { | |
351 | ||
352 | /* | |
353 | * XXX - should this be an assert? | |
354 | */ | |
355 | if (zs->zst_len == 0) { | |
356 | /* bogus stream */ | |
428870ff | 357 | ZFETCHSTAT_BUMP(zfetchstat_bogus_streams); |
34dc7c2f BB |
358 | continue; |
359 | } | |
360 | ||
361 | /* | |
362 | * We hit this case when we are in a strided prefetch stream: | |
363 | * we will read "len" blocks before "striding". | |
364 | */ | |
365 | if (zh->zst_offset >= zs->zst_offset && | |
366 | zh->zst_offset < zs->zst_offset + zs->zst_len) { | |
428870ff BB |
367 | if (prefetched) { |
368 | /* already fetched */ | |
369 | ZFETCHSTAT_BUMP(zfetchstat_stride_hits); | |
370 | rc = 1; | |
371 | goto out; | |
372 | } else { | |
373 | ZFETCHSTAT_BUMP(zfetchstat_stride_misses); | |
374 | } | |
34dc7c2f BB |
375 | } |
376 | ||
377 | /* | |
378 | * This is the forward sequential read case: we increment | |
379 | * len by one each time we hit here, so we will enter this | |
380 | * case on every read. | |
381 | */ | |
382 | if (zh->zst_offset == zs->zst_offset + zs->zst_len) { | |
383 | ||
384 | reset = !prefetched && zs->zst_len > 1; | |
385 | ||
386 | mutex_enter(&zs->zst_lock); | |
387 | ||
388 | if (zh->zst_offset != zs->zst_offset + zs->zst_len) { | |
389 | mutex_exit(&zs->zst_lock); | |
390 | goto top; | |
391 | } | |
392 | zs->zst_len += zh->zst_len; | |
393 | diff = zs->zst_len - zfetch_block_cap; | |
394 | if (diff > 0) { | |
395 | zs->zst_offset += diff; | |
396 | zs->zst_len = zs->zst_len > diff ? | |
397 | zs->zst_len - diff : 0; | |
398 | } | |
399 | zs->zst_direction = ZFETCH_FORWARD; | |
400 | ||
401 | break; | |
402 | ||
403 | /* | |
404 | * Same as above, but reading backwards through the file. | |
405 | */ | |
406 | } else if (zh->zst_offset == zs->zst_offset - zh->zst_len) { | |
407 | /* backwards sequential access */ | |
408 | ||
409 | reset = !prefetched && zs->zst_len > 1; | |
410 | ||
411 | mutex_enter(&zs->zst_lock); | |
412 | ||
413 | if (zh->zst_offset != zs->zst_offset - zh->zst_len) { | |
414 | mutex_exit(&zs->zst_lock); | |
415 | goto top; | |
416 | } | |
417 | ||
418 | zs->zst_offset = zs->zst_offset > zh->zst_len ? | |
419 | zs->zst_offset - zh->zst_len : 0; | |
420 | zs->zst_ph_offset = zs->zst_ph_offset > zh->zst_len ? | |
421 | zs->zst_ph_offset - zh->zst_len : 0; | |
422 | zs->zst_len += zh->zst_len; | |
423 | ||
424 | diff = zs->zst_len - zfetch_block_cap; | |
425 | if (diff > 0) { | |
426 | zs->zst_ph_offset = zs->zst_ph_offset > diff ? | |
427 | zs->zst_ph_offset - diff : 0; | |
428 | zs->zst_len = zs->zst_len > diff ? | |
429 | zs->zst_len - diff : zs->zst_len; | |
430 | } | |
431 | zs->zst_direction = ZFETCH_BACKWARD; | |
432 | ||
433 | break; | |
434 | ||
435 | } else if ((zh->zst_offset - zs->zst_offset - zs->zst_stride < | |
436 | zs->zst_len) && (zs->zst_len != zs->zst_stride)) { | |
437 | /* strided forward access */ | |
438 | ||
439 | mutex_enter(&zs->zst_lock); | |
440 | ||
441 | if ((zh->zst_offset - zs->zst_offset - zs->zst_stride >= | |
442 | zs->zst_len) || (zs->zst_len == zs->zst_stride)) { | |
443 | mutex_exit(&zs->zst_lock); | |
444 | goto top; | |
445 | } | |
446 | ||
447 | zs->zst_offset += zs->zst_stride; | |
448 | zs->zst_direction = ZFETCH_FORWARD; | |
449 | ||
450 | break; | |
451 | ||
452 | } else if ((zh->zst_offset - zs->zst_offset + zs->zst_stride < | |
453 | zs->zst_len) && (zs->zst_len != zs->zst_stride)) { | |
454 | /* strided reverse access */ | |
455 | ||
456 | mutex_enter(&zs->zst_lock); | |
457 | ||
458 | if ((zh->zst_offset - zs->zst_offset + zs->zst_stride >= | |
459 | zs->zst_len) || (zs->zst_len == zs->zst_stride)) { | |
460 | mutex_exit(&zs->zst_lock); | |
461 | goto top; | |
462 | } | |
463 | ||
464 | zs->zst_offset = zs->zst_offset > zs->zst_stride ? | |
465 | zs->zst_offset - zs->zst_stride : 0; | |
466 | zs->zst_ph_offset = (zs->zst_ph_offset > | |
467 | (2 * zs->zst_stride)) ? | |
468 | (zs->zst_ph_offset - (2 * zs->zst_stride)) : 0; | |
469 | zs->zst_direction = ZFETCH_BACKWARD; | |
470 | ||
471 | break; | |
472 | } | |
473 | } | |
474 | ||
475 | if (zs) { | |
476 | if (reset) { | |
477 | zstream_t *remove = zs; | |
478 | ||
428870ff | 479 | ZFETCHSTAT_BUMP(zfetchstat_stream_resets); |
34dc7c2f BB |
480 | rc = 0; |
481 | mutex_exit(&zs->zst_lock); | |
482 | rw_exit(&zf->zf_rwlock); | |
483 | rw_enter(&zf->zf_rwlock, RW_WRITER); | |
484 | /* | |
485 | * Relocate the stream, in case someone removes | |
486 | * it while we were acquiring the WRITER lock. | |
487 | */ | |
488 | for (zs = list_head(&zf->zf_stream); zs; | |
489 | zs = list_next(&zf->zf_stream, zs)) { | |
490 | if (zs == remove) { | |
491 | dmu_zfetch_stream_remove(zf, zs); | |
492 | mutex_destroy(&zs->zst_lock); | |
493 | kmem_free(zs, sizeof (zstream_t)); | |
494 | break; | |
495 | } | |
496 | } | |
497 | } else { | |
428870ff | 498 | ZFETCHSTAT_BUMP(zfetchstat_stream_noresets); |
34dc7c2f BB |
499 | rc = 1; |
500 | dmu_zfetch_dofetch(zf, zs); | |
501 | mutex_exit(&zs->zst_lock); | |
502 | } | |
503 | } | |
504 | out: | |
505 | rw_exit(&zf->zf_rwlock); | |
506 | return (rc); | |
507 | } | |
508 | ||
509 | /* | |
510 | * Clean-up state associated with a zfetch structure. This frees allocated | |
511 | * structure members, empties the zf_stream tree, and generally makes things | |
512 | * nice. This doesn't free the zfetch_t itself, that's left to the caller. | |
513 | */ | |
514 | void | |
515 | dmu_zfetch_rele(zfetch_t *zf) | |
516 | { | |
517 | zstream_t *zs; | |
518 | zstream_t *zs_next; | |
519 | ||
520 | ASSERT(!RW_LOCK_HELD(&zf->zf_rwlock)); | |
521 | ||
522 | for (zs = list_head(&zf->zf_stream); zs; zs = zs_next) { | |
523 | zs_next = list_next(&zf->zf_stream, zs); | |
524 | ||
525 | list_remove(&zf->zf_stream, zs); | |
526 | mutex_destroy(&zs->zst_lock); | |
527 | kmem_free(zs, sizeof (zstream_t)); | |
528 | } | |
529 | list_destroy(&zf->zf_stream); | |
530 | rw_destroy(&zf->zf_rwlock); | |
531 | ||
532 | zf->zf_dnode = NULL; | |
533 | } | |
534 | ||
535 | /* | |
536 | * Given a zfetch and zstream structure, insert the zstream structure into the | |
537 | * AVL tree contained within the zfetch structure. Peform the appropriate | |
538 | * book-keeping. It is possible that another thread has inserted a stream which | |
539 | * matches one that we are about to insert, so we must be sure to check for this | |
540 | * case. If one is found, return failure, and let the caller cleanup the | |
541 | * duplicates. | |
542 | */ | |
543 | static int | |
544 | dmu_zfetch_stream_insert(zfetch_t *zf, zstream_t *zs) | |
545 | { | |
546 | zstream_t *zs_walk; | |
547 | zstream_t *zs_next; | |
548 | ||
549 | ASSERT(RW_WRITE_HELD(&zf->zf_rwlock)); | |
550 | ||
551 | for (zs_walk = list_head(&zf->zf_stream); zs_walk; zs_walk = zs_next) { | |
552 | zs_next = list_next(&zf->zf_stream, zs_walk); | |
553 | ||
554 | if (dmu_zfetch_streams_equal(zs_walk, zs)) { | |
428870ff | 555 | return (0); |
34dc7c2f BB |
556 | } |
557 | } | |
558 | ||
559 | list_insert_head(&zf->zf_stream, zs); | |
560 | zf->zf_stream_cnt++; | |
34dc7c2f BB |
561 | return (1); |
562 | } | |
563 | ||
564 | ||
565 | /* | |
566 | * Walk the list of zstreams in the given zfetch, find an old one (by time), and | |
567 | * reclaim it for use by the caller. | |
568 | */ | |
569 | static zstream_t * | |
570 | dmu_zfetch_stream_reclaim(zfetch_t *zf) | |
571 | { | |
572 | zstream_t *zs; | |
573 | ||
574 | if (! rw_tryenter(&zf->zf_rwlock, RW_WRITER)) | |
575 | return (0); | |
576 | ||
577 | for (zs = list_head(&zf->zf_stream); zs; | |
578 | zs = list_next(&zf->zf_stream, zs)) { | |
579 | ||
428870ff | 580 | if (((ddi_get_lbolt() - zs->zst_last)/hz) > zfetch_min_sec_reap) |
34dc7c2f BB |
581 | break; |
582 | } | |
583 | ||
584 | if (zs) { | |
585 | dmu_zfetch_stream_remove(zf, zs); | |
586 | mutex_destroy(&zs->zst_lock); | |
587 | bzero(zs, sizeof (zstream_t)); | |
588 | } else { | |
589 | zf->zf_alloc_fail++; | |
590 | } | |
591 | rw_exit(&zf->zf_rwlock); | |
592 | ||
593 | return (zs); | |
594 | } | |
595 | ||
596 | /* | |
597 | * Given a zfetch and zstream structure, remove the zstream structure from its | |
598 | * container in the zfetch structure. Perform the appropriate book-keeping. | |
599 | */ | |
600 | static void | |
601 | dmu_zfetch_stream_remove(zfetch_t *zf, zstream_t *zs) | |
602 | { | |
603 | ASSERT(RW_WRITE_HELD(&zf->zf_rwlock)); | |
604 | ||
605 | list_remove(&zf->zf_stream, zs); | |
606 | zf->zf_stream_cnt--; | |
607 | } | |
608 | ||
609 | static int | |
610 | dmu_zfetch_streams_equal(zstream_t *zs1, zstream_t *zs2) | |
611 | { | |
612 | if (zs1->zst_offset != zs2->zst_offset) | |
613 | return (0); | |
614 | ||
615 | if (zs1->zst_len != zs2->zst_len) | |
616 | return (0); | |
617 | ||
618 | if (zs1->zst_stride != zs2->zst_stride) | |
619 | return (0); | |
620 | ||
621 | if (zs1->zst_ph_offset != zs2->zst_ph_offset) | |
622 | return (0); | |
623 | ||
624 | if (zs1->zst_cap != zs2->zst_cap) | |
625 | return (0); | |
626 | ||
627 | if (zs1->zst_direction != zs2->zst_direction) | |
628 | return (0); | |
629 | ||
630 | return (1); | |
631 | } | |
632 | ||
633 | /* | |
634 | * This is the prefetch entry point. It calls all of the other dmu_zfetch | |
635 | * routines to create, delete, find, or operate upon prefetch streams. | |
636 | */ | |
637 | void | |
638 | dmu_zfetch(zfetch_t *zf, uint64_t offset, uint64_t size, int prefetched) | |
639 | { | |
640 | zstream_t zst; | |
641 | zstream_t *newstream; | |
642 | int fetched; | |
643 | int inserted; | |
644 | unsigned int blkshft; | |
645 | uint64_t blksz; | |
646 | ||
647 | if (zfs_prefetch_disable) | |
648 | return; | |
649 | ||
650 | /* files that aren't ln2 blocksz are only one block -- nothing to do */ | |
651 | if (!zf->zf_dnode->dn_datablkshift) | |
652 | return; | |
653 | ||
654 | /* convert offset and size, into blockid and nblocks */ | |
655 | blkshft = zf->zf_dnode->dn_datablkshift; | |
656 | blksz = (1 << blkshft); | |
657 | ||
658 | bzero(&zst, sizeof (zstream_t)); | |
659 | zst.zst_offset = offset >> blkshft; | |
660 | zst.zst_len = (P2ROUNDUP(offset + size, blksz) - | |
661 | P2ALIGN(offset, blksz)) >> blkshft; | |
662 | ||
663 | fetched = dmu_zfetch_find(zf, &zst, prefetched); | |
428870ff BB |
664 | if (fetched) { |
665 | ZFETCHSTAT_BUMP(zfetchstat_hits); | |
666 | } else { | |
667 | ZFETCHSTAT_BUMP(zfetchstat_misses); | |
668 | if (fetched = dmu_zfetch_colinear(zf, &zst)) { | |
669 | ZFETCHSTAT_BUMP(zfetchstat_colinear_hits); | |
670 | } else { | |
671 | ZFETCHSTAT_BUMP(zfetchstat_colinear_misses); | |
672 | } | |
34dc7c2f BB |
673 | } |
674 | ||
675 | if (!fetched) { | |
676 | newstream = dmu_zfetch_stream_reclaim(zf); | |
677 | ||
678 | /* | |
679 | * we still couldn't find a stream, drop the lock, and allocate | |
680 | * one if possible. Otherwise, give up and go home. | |
681 | */ | |
428870ff BB |
682 | if (newstream) { |
683 | ZFETCHSTAT_BUMP(zfetchstat_reclaim_successes); | |
684 | } else { | |
34dc7c2f BB |
685 | uint64_t maxblocks; |
686 | uint32_t max_streams; | |
687 | uint32_t cur_streams; | |
688 | ||
428870ff | 689 | ZFETCHSTAT_BUMP(zfetchstat_reclaim_failures); |
34dc7c2f BB |
690 | cur_streams = zf->zf_stream_cnt; |
691 | maxblocks = zf->zf_dnode->dn_maxblkid; | |
692 | ||
693 | max_streams = MIN(zfetch_max_streams, | |
694 | (maxblocks / zfetch_block_cap)); | |
695 | if (max_streams == 0) { | |
696 | max_streams++; | |
697 | } | |
698 | ||
699 | if (cur_streams >= max_streams) { | |
700 | return; | |
701 | } | |
34dc7c2f BB |
702 | newstream = kmem_zalloc(sizeof (zstream_t), KM_SLEEP); |
703 | } | |
704 | ||
705 | newstream->zst_offset = zst.zst_offset; | |
706 | newstream->zst_len = zst.zst_len; | |
707 | newstream->zst_stride = zst.zst_len; | |
708 | newstream->zst_ph_offset = zst.zst_len + zst.zst_offset; | |
709 | newstream->zst_cap = zst.zst_len; | |
710 | newstream->zst_direction = ZFETCH_FORWARD; | |
428870ff | 711 | newstream->zst_last = ddi_get_lbolt(); |
34dc7c2f BB |
712 | |
713 | mutex_init(&newstream->zst_lock, NULL, MUTEX_DEFAULT, NULL); | |
714 | ||
715 | rw_enter(&zf->zf_rwlock, RW_WRITER); | |
716 | inserted = dmu_zfetch_stream_insert(zf, newstream); | |
717 | rw_exit(&zf->zf_rwlock); | |
718 | ||
719 | if (!inserted) { | |
720 | mutex_destroy(&newstream->zst_lock); | |
721 | kmem_free(newstream, sizeof (zstream_t)); | |
722 | } | |
723 | } | |
724 | } |