Commit | Line | Data |
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c966e8e8 WD |
1 | From: Tobi Oetiker tobi{at}oetiker.ch |
2 | Date: 2007-04-23 | |
3 | ||
4 | I am using rsync for hard-link backup. I found that there is a | |
5 | major problem with frequent backup filling up the file system cache | |
6 | with all the data from the files being backed up. The effect is | |
7 | that all the other 'sensible' data in the cache gets thrown out in | |
8 | the process. This is rather unfortunate as the performance of the | |
9 | system becomes very bad after running rsync. | |
10 | ||
11 | Some research showed, that | |
12 | ||
13 | posix_fadvise64(fd, 0, 0,POSIX_FADV_DONTNEED); | |
14 | ||
15 | would tell the OS that it should not keep the file in cache. I | |
16 | have written a patch for rsync that adds the | |
17 | ||
18 | --drop-cache | |
19 | ||
20 | option which activates posix_fadvise64. | |
21 | ||
22 | There are some caveats though: | |
23 | ||
24 | * When calling posix_fadvise64 while writing a file, only the | |
25 | part of the cache will be release which has already been | |
26 | written to disk. This means we have to call fdatasync before | |
27 | calling posix_fadvise64 and this will unfortunately slow down | |
28 | operations considerably. On my test system I get 240 KByte/s. | |
29 | ||
30 | The patch has been optimized, so that the impact on large files | |
31 | will be considerably lowered by calling posix_fadvise64 only | |
32 | after a few megabytes have been written. | |
33 | ||
34 | * When reading a file which has been cached *Before* rsync read | |
35 | it, the content of the file will be released from cache never | |
36 | the less, which may not be intended. I have unfortunately not | |
37 | found a method for determining if a file is in cache or not | |
38 | (ideas?) | |
39 | ||
40 | I found that running rsync of an lvm snapshot is a good way | |
41 | around this problem, since the snapshot data is cached | |
42 | separately from the original. It has the additional benefit of | |
43 | making the backups more consistent. | |
44 | ||
45 | * I don't really know the rsync code, so it may be that the patch | |
46 | is calling fadvise for files where this would not be necessary. | |
47 | ||
48 | * The patch is tested only on Linux 2.6.18 | |
49 | ||
50 | If you have any input on this, please let me know. | |
51 | ||
52 | You can get the latest edition of the patch from | |
53 | ||
54 | http://tobi.oetiker.ch/patches/ | |
55 | ||
56 | cheers | |
57 | tobi | |
58 | ||
59 | Changes: | |
60 | ||
61 | 2007-04-23 | |
62 | ||
63 | * pass --drop-cache on to the remote server | |
64 | * make test works now | |
65 | ||
cc3e685d WD |
66 | diff --git a/checksum.c b/checksum.c |
67 | --- a/checksum.c | |
68 | +++ b/checksum.c | |
14317044 | 69 | @@ -26,6 +26,10 @@ extern int protocol_version; |
c966e8e8 | 70 | |
14317044 | 71 | int csum_length = SHORT_SUM_LENGTH; /* initial value */ |
c966e8e8 | 72 | |
14317044 WD |
73 | +#ifdef HAVE_POSIX_FADVISE64 |
74 | +#define close(fd) fadv_close(fd) | |
75 | +#endif | |
76 | + | |
77 | /* | |
78 | a simple 32 bit checksum that can be upadted from either end | |
79 | (inspired by Mark Adler's Adler-32 checksum) | |
cc3e685d WD |
80 | diff --git a/cleanup.c b/cleanup.c |
81 | --- a/cleanup.c | |
82 | +++ b/cleanup.c | |
14317044 WD |
83 | @@ -46,7 +46,13 @@ void close_all(void) |
84 | int fd; | |
85 | int ret; | |
86 | STRUCT_STAT st; | |
87 | +#endif | |
88 | + | |
89 | +#ifdef HAVE_POSIX_FADVISE64 | |
90 | + fadv_close_all(); | |
91 | +#endif | |
92 | ||
93 | +#ifdef SHUTDOWN_ALL_SOCKETS | |
94 | max_fd = sysconf(_SC_OPEN_MAX) - 1; | |
95 | for (fd = max_fd; fd >= 0; fd--) { | |
96 | if ((ret = do_fstat(fd, &st)) == 0) { | |
cc3e685d WD |
97 | diff --git a/configure.in b/configure.in |
98 | --- a/configure.in | |
99 | +++ b/configure.in | |
100 | @@ -552,7 +552,7 @@ AC_CHECK_FUNCS(waitpid wait4 getcwd strdup chown chmod lchmod mknod mkfifo \ | |
14317044 WD |
101 | strlcat strlcpy strtol mallinfo getgroups setgroups geteuid getegid \ |
102 | setlocale setmode open64 lseek64 mkstemp64 mtrace va_copy __va_copy \ | |
103 | strerror putenv iconv_open locale_charset nl_langinfo getxattr \ | |
7c4c2959 WD |
104 | - extattr_get_link sigaction sigprocmask setattrlist) |
105 | + extattr_get_link sigaction sigprocmask setattrlist posix_fadvise64) | |
14317044 WD |
106 | |
107 | AC_CHECK_FUNCS(getpgrp tcgetpgrp) | |
108 | if test $ac_cv_func_getpgrp = yes; then | |
cc3e685d WD |
109 | diff --git a/fileio.c b/fileio.c |
110 | --- a/fileio.c | |
111 | +++ b/fileio.c | |
14317044 | 112 | @@ -30,6 +30,12 @@ extern int sparse_files; |
c966e8e8 | 113 | static char last_byte; |
c8a8b4a7 | 114 | static size_t sparse_seek = 0; |
c966e8e8 | 115 | |
14317044 WD |
116 | +#ifdef HAVE_POSIX_FADVISE64 |
117 | +#define close(fd) fadv_close(fd) | |
118 | +#define read(fd,buf,len) fadv_read(fd,buf,len) | |
119 | +#define write(fd,buf,len) fadv_write(fd,buf,len) | |
120 | +#endif | |
c966e8e8 WD |
121 | + |
122 | int sparse_end(int f) | |
123 | { | |
c8a8b4a7 | 124 | int ret; |
cc3e685d WD |
125 | diff --git a/generator.c b/generator.c |
126 | --- a/generator.c | |
127 | +++ b/generator.c | |
e2b0842a | 128 | @@ -112,6 +112,10 @@ static int need_retouch_dir_times; |
c8a8b4a7 | 129 | static int need_retouch_dir_perms; |
14317044 | 130 | static const char *solo_file = NULL; |
c966e8e8 | 131 | |
14317044 WD |
132 | +#ifdef HAVE_POSIX_FADVISE64 |
133 | +#define close(fd) fadv_close(fd) | |
134 | +#endif | |
135 | + | |
136 | /* For calling delete_item() and delete_dir_contents(). */ | |
137 | #define DEL_RECURSE (1<<1) /* recurse */ | |
138 | #define DEL_DIR_IS_EMPTY (1<<2) /* internal delete_FUNCTIONS use only */ | |
cc3e685d WD |
139 | diff --git a/options.c b/options.c |
140 | --- a/options.c | |
141 | +++ b/options.c | |
f2863bc0 | 142 | @@ -59,6 +59,7 @@ int preserve_uid = 0; |
c8a8b4a7 | 143 | int preserve_gid = 0; |
c966e8e8 | 144 | int preserve_times = 0; |
c966e8e8 WD |
145 | int update_only = 0; |
146 | +int drop_cache = 0; | |
147 | int cvs_exclude = 0; | |
148 | int dry_run = 0; | |
149 | int do_xfers = 1; | |
f2863bc0 | 150 | @@ -321,6 +322,9 @@ void usage(enum logcode F) |
c966e8e8 WD |
151 | rprintf(F," --backup-dir=DIR make backups into hierarchy based in DIR\n"); |
152 | rprintf(F," --suffix=SUFFIX set backup suffix (default %s w/o --backup-dir)\n",BACKUP_SUFFIX); | |
153 | rprintf(F," -u, --update skip files that are newer on the receiver\n"); | |
14317044 | 154 | +#ifdef HAVE_POSIX_FADVISE64 |
c966e8e8 | 155 | + rprintf(F," --drop-cache tell OS to drop caching of file data\n"); |
14317044 | 156 | +#endif |
c966e8e8 WD |
157 | rprintf(F," --inplace update destination files in-place (SEE MAN PAGE)\n"); |
158 | rprintf(F," --append append data onto shorter files\n"); | |
c8a8b4a7 | 159 | rprintf(F," --append-verify like --append, but with old data in file checksum\n"); |
f2863bc0 | 160 | @@ -525,6 +529,9 @@ static struct poptOption long_options[] = { |
c966e8e8 WD |
161 | {"size-only", 0, POPT_ARG_NONE, &size_only, 0, 0, 0 }, |
162 | {"one-file-system", 'x', POPT_ARG_NONE, 0, 'x', 0, 0 }, | |
163 | {"update", 'u', POPT_ARG_NONE, &update_only, 0, 0, 0 }, | |
14317044 | 164 | +#ifdef HAVE_POSIX_FADVISE64 |
c966e8e8 | 165 | + {"drop-cache", 0, POPT_ARG_NONE, &drop_cache, 0, 0, 0 }, |
14317044 | 166 | +#endif |
c966e8e8 WD |
167 | {"existing", 0, POPT_ARG_NONE, &ignore_non_existing, 0, 0, 0 }, |
168 | {"ignore-non-existing",0,POPT_ARG_NONE, &ignore_non_existing, 0, 0, 0 }, | |
169 | {"ignore-existing", 0, POPT_ARG_NONE, &ignore_existing, 0, 0, 0 }, | |
f2863bc0 | 170 | @@ -1670,6 +1677,11 @@ void server_options(char **args, int *argc_p) |
c966e8e8 WD |
171 | if (!am_sender) |
172 | args[ac++] = "--sender"; | |
173 | ||
14317044 | 174 | +#ifdef HAVE_POSIX_FADVISE64 |
c966e8e8 WD |
175 | + if (drop_cache) |
176 | + args[ac++] = "--drop-cache"; | |
14317044 | 177 | +#endif |
c966e8e8 WD |
178 | + |
179 | x = 1; | |
180 | argstr[0] = '-'; | |
c8a8b4a7 | 181 | |
cc3e685d WD |
182 | diff --git a/receiver.c b/receiver.c |
183 | --- a/receiver.c | |
184 | +++ b/receiver.c | |
14317044 WD |
185 | @@ -62,6 +62,10 @@ static int phase = 0, redoing = 0; |
186 | /* We're either updating the basis file or an identical copy: */ | |
e2b0842a | 187 | static int updating_basis_or_equiv; |
c966e8e8 | 188 | |
14317044 WD |
189 | +#ifdef HAVE_POSIX_FADVISE64 |
190 | +#define close(fd) fadv_close(fd) | |
191 | +#endif | |
192 | + | |
193 | /* | |
194 | * get_tmpname() - create a tmp filename for a given filename | |
195 | * | |
cc3e685d WD |
196 | diff --git a/rsync.yo b/rsync.yo |
197 | --- a/rsync.yo | |
198 | +++ b/rsync.yo | |
199 | @@ -352,6 +352,7 @@ to the detailed description below for a complete description. verb( | |
c966e8e8 WD |
200 | --super receiver attempts super-user activities |
201 | --fake-super store/recover privileged attrs using xattrs | |
202 | -S, --sparse handle sparse files efficiently | |
203 | + --drop-cache tell OS to drop caching of file data | |
e2b0842a | 204 | -n, --dry-run perform a trial run with no changes made |
f2863bc0 | 205 | -W, --whole-file copy files whole (w/o delta-xfer algorithm) |
c966e8e8 | 206 | -x, --one-file-system don't cross filesystem boundaries |
cc3e685d | 207 | @@ -1023,6 +1024,10 @@ NOTE: Don't use this option when the destination is a Solaris "tmpfs" |
c966e8e8 WD |
208 | filesystem. It doesn't seem to handle seeks over null regions |
209 | correctly and ends up corrupting the files. | |
210 | ||
211 | +dit(bf(--drop-cache)) Tell the OS to drop the caching of the file data. This | |
212 | +prevents rsync from filling up the filesystem cache. This can sometimes help | |
213 | +to make a system perform better by keeping non-rsync files in the disk cache. | |
214 | + | |
e2b0842a WD |
215 | dit(bf(-n, --dry-run)) This makes rsync perform a trial run that doesn't |
216 | make any changes (and produces mostly the same output as a real run). It | |
217 | is most commonly used in combination with the bf(-v, --verbose) and/or | |
cc3e685d WD |
218 | diff --git a/sender.c b/sender.c |
219 | --- a/sender.c | |
220 | +++ b/sender.c | |
14317044 WD |
221 | @@ -46,6 +46,10 @@ extern int write_batch; |
222 | extern struct stats stats; | |
c8a8b4a7 | 223 | extern struct file_list *cur_flist, *first_flist, *dir_flist; |
c966e8e8 | 224 | |
14317044 WD |
225 | +#ifdef HAVE_POSIX_FADVISE64 |
226 | +#define close(fd) fadv_close(fd) | |
227 | +#endif | |
228 | + | |
229 | /** | |
230 | * @file | |
231 | * | |
cc3e685d WD |
232 | diff --git a/t_unsafe.c b/t_unsafe.c |
233 | --- a/t_unsafe.c | |
234 | +++ b/t_unsafe.c | |
c966e8e8 WD |
235 | @@ -28,6 +28,7 @@ int am_root = 0; |
236 | int read_only = 0; | |
237 | int list_only = 0; | |
238 | int verbose = 0; | |
239 | +int drop_cache = 0; | |
240 | int preserve_perms = 0; | |
241 | ||
242 | int | |
cc3e685d WD |
243 | diff --git a/util.c b/util.c |
244 | --- a/util.c | |
245 | +++ b/util.c | |
c8a8b4a7 | 246 | @@ -26,6 +26,7 @@ |
c966e8e8 WD |
247 | extern int verbose; |
248 | extern int dry_run; | |
c966e8e8 | 249 | extern int module_id; |
14317044 | 250 | +extern int drop_cache; |
c966e8e8 WD |
251 | extern int modify_window; |
252 | extern int relative_paths; | |
14317044 | 253 | extern int human_readable; |
c8a8b4a7 | 254 | @@ -41,6 +42,131 @@ char curr_dir[MAXPATHLEN]; |
c966e8e8 WD |
255 | unsigned int curr_dir_len; |
256 | int curr_dir_depth; /* This is only set for a sanitizing daemon. */ | |
257 | ||
14317044 WD |
258 | +#ifdef HAVE_POSIX_FADVISE64 |
259 | +#define FADV_BUFFER_SIZE 1024*1024*16 | |
c966e8e8 | 260 | + |
14317044 WD |
261 | +static struct stat fadv_fd_stat[1024]; |
262 | +static off_t fadv_fd_pos[1024]; | |
263 | +static int fadv_fd_init = 0; | |
264 | +static int fadv_max_fd = 0; | |
265 | +static int fadv_close_ring_tail = 0; | |
266 | +static int fadv_close_ring_head = 0; | |
267 | +static int fadv_close_ring_size = 0; | |
268 | +static int fadv_close_ring[1024]; | |
269 | +static int fadv_close_buffer_size = 0; | |
c966e8e8 | 270 | + |
14317044 WD |
271 | +static void fadv_fd_init_func(void) |
272 | +{ | |
273 | + if (fadv_fd_init == 0) { | |
274 | + int i; | |
275 | + fadv_fd_init = 1; | |
276 | + if (fadv_max_fd == 0){ | |
277 | + fadv_max_fd = sysconf(_SC_OPEN_MAX) - 20; | |
278 | + if (fadv_max_fd < 0) | |
279 | + fadv_max_fd = 1; | |
280 | + if (fadv_max_fd > 1000) | |
281 | + fadv_max_fd = 1000; | |
282 | + } | |
283 | + for (i = 0; i < fadv_max_fd; i++) { | |
284 | + fadv_fd_pos[i] = 0; | |
285 | + fadv_fd_stat[i].st_dev = 0; | |
286 | + fadv_fd_stat[i].st_ino = 0; | |
287 | + } | |
288 | + } | |
c966e8e8 | 289 | +} |
14317044 WD |
290 | + |
291 | +static void fadv_drop(int fd, int sync) | |
292 | +{ | |
293 | + struct stat sb; | |
294 | + int pos; | |
295 | + | |
296 | + /* Trail 1 MB behind in dropping. we do this to make | |
297 | + * sure that the same block or stripe does not have | |
298 | + * to be written twice. */ | |
299 | + if (fd > fadv_max_fd) | |
300 | + return; | |
301 | + pos = lseek(fd, 0, SEEK_CUR) - 1024*1024; | |
c966e8e8 | 302 | + fadv_fd_init_func(); |
14317044 WD |
303 | + fstat(fd, &sb); |
304 | + if (fadv_fd_stat[fd].st_dev == sb.st_dev | |
305 | + && fadv_fd_stat[fd].st_ino == sb.st_ino) { | |
306 | + if (fadv_fd_pos[fd] < pos - FADV_BUFFER_SIZE) { | |
307 | + if (sync) { | |
308 | + /* If the file is not flushed to disk before calling fadvise, | |
309 | + * then the Cache will not be freed and the advise gets ignored | |
310 | + * this does give a severe hit on performance. If only there | |
311 | + * was a way to mark cache so that it gets release once the data | |
312 | + * is written to disk. */ | |
313 | + fdatasync(fd); | |
314 | + } | |
315 | + posix_fadvise64(fd, 0, pos, POSIX_FADV_DONTNEED); | |
316 | + fadv_fd_pos[fd] = pos; | |
317 | + } | |
318 | + } else { | |
319 | + fadv_fd_stat[fd].st_dev = sb.st_dev; | |
320 | + fadv_fd_stat[fd].st_ino = sb.st_ino; | |
321 | + fadv_fd_pos[fd] = 0; | |
322 | + } | |
c966e8e8 | 323 | +} |
14317044 | 324 | + |
c966e8e8 WD |
325 | +ssize_t fadv_write(int fd, const void *buf, size_t count) |
326 | +{ | |
14317044 WD |
327 | + int ret = write(fd, buf, count); |
328 | + if (drop_cache) | |
329 | + fadv_drop(fd, 1); | |
330 | + return ret; | |
c966e8e8 WD |
331 | +} |
332 | + | |
333 | +ssize_t fadv_read(int fd, void *buf, size_t count) | |
334 | +{ | |
14317044 WD |
335 | + int ret = read(fd, buf, count); |
336 | + if (drop_cache) | |
337 | + fadv_drop(fd, 0); | |
338 | + return ret; | |
339 | +} | |
340 | + | |
341 | +void fadv_close_all(void) | |
342 | +{ | |
343 | + while (fadv_close_ring_size > 0){ | |
344 | + fdatasync(fadv_close_ring[fadv_close_ring_tail]); | |
345 | + posix_fadvise64(fadv_close_ring[fadv_close_ring_tail], 0, 0,POSIX_FADV_DONTNEED); | |
346 | + fadv_close_ring_size--; | |
347 | + close(fadv_close_ring[fadv_close_ring_tail]); | |
348 | + fadv_close_ring_tail = (fadv_close_ring_tail + 1) % fadv_max_fd; | |
349 | + fadv_close_buffer_size = 0; | |
350 | + } | |
c966e8e8 WD |
351 | +} |
352 | + | |
14317044 WD |
353 | +int fadv_close(int fd) |
354 | +{ | |
355 | + if (drop_cache) { | |
356 | + /* If the file is not flushed to disk before calling fadvise, | |
357 | + * then the Cache will not be freed and the advise gets ignored | |
358 | + * this does give a severe hit on performance. So instead of doing | |
359 | + * it right away, we save us a copy of the filehandle and do it | |
360 | + * some time before we are out of filehandles. This speeds | |
361 | + * up operation for small files massively. It is directly | |
362 | + * related to the number of spare file handles you have. */ | |
363 | + int newfd = dup(fd); | |
364 | + int pos = lseek(fd, 0, SEEK_CUR); | |
365 | + fadv_fd_init_func(); | |
366 | + fadv_close_buffer_size += pos - fadv_fd_pos[fd]; | |
367 | + fadv_close_ring[fadv_close_ring_head] = newfd; | |
368 | + fadv_close_ring_head = (fadv_close_ring_head + 1) % fadv_max_fd; | |
369 | + fadv_close_ring_size ++; | |
370 | + if (fadv_close_ring_size == fadv_max_fd || fadv_close_buffer_size > 1024*1024 ){ | |
371 | + /* it seems fastest to drop things 'in groups' */ | |
372 | + fadv_close_all(); | |
373 | + } | |
374 | + } | |
375 | + return close(fd); | |
c966e8e8 | 376 | +} |
14317044 WD |
377 | + |
378 | +#define close(fd) fadv_close(fd) | |
379 | +#define read(fd,buf,len) fadv_read(fd,buf,len) | |
380 | +#define write(fd,buf,len) fadv_write(fd,buf,len) | |
381 | +#endif | |
c966e8e8 WD |
382 | + |
383 | /* Set a fd into nonblocking mode. */ | |
384 | void set_nonblocking(int fd) | |
385 | { |