├── CMakeLists.txt ├── COPYING ├── README.md ├── ksm-wrapper └── libksm_preload.c /CMakeLists.txt: -------------------------------------------------------------------------------- 1 | # TODO(unbrice): Confirm it works with earlier versions. 2 | # So far, it's tested with 2.8.12.2 3 | cmake_minimum_required(VERSION 2.8) 4 | 5 | project(KSM_PRELOAD) 6 | 7 | add_library(ksm_preload SHARED libksm_preload.c) 8 | target_link_libraries(ksm_preload dl) 9 | install( 10 | TARGETS ksm_preload 11 | RUNTIME DESTINATION bin 12 | LIBRARY DESTINATION share/ksm_preload 13 | NAMELINK_SKIP 14 | ) 15 | 16 | install(PROGRAMS ksm-wrapper DESTINATION bin) 17 | 18 | -------------------------------------------------------------------------------- /COPYING: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. 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Interpretation of Sections 15 and 16. 613 | 614 | If the disclaimer of warranty and limitation of liability provided 615 | above cannot be given local legal effect according to their terms, 616 | reviewing courts shall apply local law that most closely approximates 617 | an absolute waiver of all civil liability in connection with the 618 | Program, unless a warranty or assumption of liability accompanies a 619 | copy of the Program in return for a fee. 620 | 621 | END OF TERMS AND CONDITIONS 622 | 623 | How to Apply These Terms to Your New Programs 624 | 625 | If you develop a new program, and you want it to be of the greatest 626 | possible use to the public, the best way to achieve this is to make it 627 | free software which everyone can redistribute and change under these terms. 628 | 629 | To do so, attach the following notices to the program. It is safest 630 | to attach them to the start of each source file to most effectively 631 | state the exclusion of warranty; and each file should have at least 632 | the "copyright" line and a pointer to where the full notice is found. 633 | 634 | 635 | Copyright (C) 636 | 637 | This program is free software: you can redistribute it and/or modify 638 | it under the terms of the GNU General Public License as published by 639 | the Free Software Foundation, either version 3 of the License, or 640 | (at your option) any later version. 641 | 642 | This program is distributed in the hope that it will be useful, 643 | but WITHOUT ANY WARRANTY; without even the implied warranty of 644 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | Copyright (C) 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # Introduction 2 | 3 | Enables legacy applications to leverage Linux's memory deduplication. 4 | Only works on Linux ≥ 2.6.32. 5 | 6 | If you have multiple processes generating similar data (like multiple 7 | applications serving different vhosts), this easy to use tool may 8 | allow you to spare memory by deduplicating it. If two pages (typically 9 | consecutive blocks of 4k) are identical, they will be merged to reduce 10 | memory usage. 11 | 12 | 13 | # Building and installing 14 | 15 | First, please make sure you have installed the requirements: 16 | - Kernel headers (linux-headers under Ubuntu) 17 | - a build toolchain (build-essentials under Ubuntu) 18 | - cmake > 2.8 (earlier version may work, please tell me if so) 19 | 20 | The quick and dirty way: 21 | ```bash 22 | cmake . 23 | make 24 | sudo make install 25 | ``` 26 | 27 | # More 28 | 29 | More information, howto, on [vleu.net/ksm_preload](http://vleu.net/ksm_preload/). 30 | -------------------------------------------------------------------------------- /ksm-wrapper: -------------------------------------------------------------------------------- 1 | #!/bin/sh 2 | # Runs the provided executable with ksm-preload.so , which enables KSM 3 | # on heap-allocated memory. 4 | 5 | # By Brice Arnould 6 | # Copyright (C) 2011 Gandi SAS. 7 | # 8 | # This program is free software: you can redistribute it and/or modify 9 | # it under the terms of the GNU General Public License as published by 10 | # the Free Software Foundation, either version 3 of the License, or 11 | # (at your option) any later version. 12 | # 13 | # This program is distributed in the hope that it will be useful, 14 | # but WITHOUT ANY WARRANTY; without even the implied warranty of 15 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 | # GNU General Public License for more details. 17 | # 18 | # You should have received a copy of the GNU General Public License 19 | # along with this program. If not, see . 20 | 21 | readonly KSM_PATH=$(cd $(dirname $0) ; pwd) 22 | readonly KSM_SO_GIT="${KSM_PATH}/libksm_preload.so" 23 | readonly KSM_SO_CMAKE="${KSM_PATH}/../share/ksm_preload/libksm_preload.so" 24 | 25 | if [ -x "${KSM_SO_GIT}" ]; then 26 | readonly KSM_SO="${KSM_SO_GIT}" 27 | elif [ -s "${KSM_SO_CMAKE}" ]; then 28 | readonly KSM_SO="${KSM_SO_CMAKE}" 29 | else 30 | echo $KSM_SO_CMAKE 31 | echo "Could not find libksm_preload.so. Have you compiled it with 'make' ?" 32 | exit 1 33 | fi 34 | 35 | export LD_PRELOAD="${LD_PRELOAD} ${KSM_SO}" 36 | exec "$@" 37 | -------------------------------------------------------------------------------- /libksm_preload.c: -------------------------------------------------------------------------------- 1 | /* By Brice Arnould 2 | * Copyright (C) 2011 Gandi SAS. 3 | * 4 | * This program is free software: you can redistribute it and/or modify 5 | * it under the terms of the GNU General Public License as published by 6 | * the Free Software Foundation, either version 3 of the License, or 7 | * (at your option) any later version. 8 | * 9 | * This program is distributed in the hope that it will be useful, 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 | * GNU General Public License for more details. 13 | * 14 | * You should have received a copy of the GNU General Public License 15 | * along with this program. If not, see . 16 | * 17 | */ 18 | 19 | /* Enables KSM on heap-allocated memory. 20 | * Usage: make 21 | * LD_PRELOAD+=./ksm-preload.so command args ... 22 | */ 23 | 24 | 25 | #define _GNU_SOURCE // dlsym(), mremap() 26 | #include // dlsym() 27 | #include // mmap(), mmap2(), mremap() 28 | #include // syscall() 29 | #include // SYS_mmap, SYS_mmap2 30 | 31 | #include 32 | #include 33 | #include 34 | #include 35 | #include 36 | #include 37 | #include 38 | #include // fprintf(), stderr 39 | #include // uintptr_t 40 | #include 41 | 42 | /* The default value for merge_threshold */ 43 | static const char *const MERGE_THRESHOLD_ENV_NAME = "KSMP_MERGE_THRESHOLD"; 44 | 45 | /* mmap2 is only defined on some 32 bit systems 46 | * (actually, it might only be defined i386) 47 | */ 48 | #ifdef SYS_mmap2 49 | # define MMAP2_ENABLED 1 50 | #else 51 | # define MMAP2_ENABLED 0 52 | #endif 53 | 54 | #ifdef GCC 55 | # define likely(x) __builtin_expect((x),1) 56 | #else 57 | # define likely(x) (x) 58 | #endif 59 | 60 | 61 | 62 | /******** GLOBAL STATE ********/ 63 | 64 | /* Aliases for function types. 65 | * Just a little spoon of syntactic sugar to help the medicine go down 66 | */ 67 | typedef void *calloc_function (size_t nmemb, size_t size); 68 | typedef void *malloc_function (size_t size); 69 | typedef void *mmap_function (void *start, size_t length, int prot, int flags, 70 | int fd, off_t offset); 71 | typedef void *mmap2_function (void *start, size_t length, int prot, int flags, 72 | int fd, off_t pgoffset); 73 | typedef void *mremap_function (void *old_address, size_t old_length, 74 | size_t new_length, int flags, ...); 75 | typedef void *realloc_function (void *addr, size_t size); 76 | 77 | /* Declares the libc version of the functions we hook */ 78 | extern calloc_function __libc_calloc; 79 | extern malloc_function __libc_malloc; 80 | extern realloc_function __libc_realloc; 81 | extern void __libc_free (void *ptr); 82 | 83 | /* Directly calls the mmap() syscall */ 84 | static void * 85 | kernel_mmap (void *start, size_t length, int prot, int flags, 86 | int fd, off_t offset) 87 | { 88 | #ifdef __i386__ 89 | uint32_t args[6] = 90 | { (uint32_t) start, (uint32_t) length, prot, flags, fd, offset }; 91 | return (void *) syscall (SYS_mmap, args); 92 | #else 93 | return (void *) syscall (SYS_mmap, start, length, prot, flags, fd, offset); 94 | #endif 95 | } 96 | 97 | #if MMAP2_ENABLED 98 | /* Directly calls the mmap2() syscall */ 99 | static void * 100 | kernel_mmap2 (void *start, size_t length, int prot, int flags, 101 | int fd, off_t pgoffset) 102 | { 103 | assert (MMAP2_ENABLED); 104 | return (void *) syscall (SYS_mmap2, start, length, prot, flags, fd, 105 | pgoffset); 106 | } 107 | #else 108 | /* If MMAP2_ENABLED is not defined, we won't export mmap2, so this 109 | * function should not be called. If it is called, it error()s. 110 | */ 111 | static void * 112 | kernel_mmap2 () 113 | { 114 | error (1, 0, "ksm_preload: Fatal error: mmap2 was called but not" 115 | " exported. Please contact unbrice@vleu.net ."); 116 | return NULL; 117 | } 118 | #endif 119 | 120 | /* This structure contains all global variables. */ 121 | static struct 122 | { 123 | /* The functions that the program would be using if we weren't preloaded. 124 | * Temporarily set to "safe" values during initialisation 125 | */ 126 | calloc_function *ext_calloc; 127 | malloc_function *ext_malloc; 128 | mmap_function *ext_mmap; 129 | mmap2_function *ext_mmap2; 130 | mremap_function *ext_mremap; 131 | realloc_function *ext_realloc; 132 | /* The page size, this value is temporary and will be fixed 133 | * by setup() 134 | */ 135 | unsigned long page_size; 136 | /* Zones smaller than this won't be merged */ 137 | int merge_threshold; 138 | } globals = 139 | { 140 | #if __GLIBC_PREREQ(2,11) || KSMP_FORCE_LIBC 141 | __libc_calloc, // libc's calloc 142 | __libc_malloc, // libc's malloc 143 | kernel_mmap, // calls kernel's mmap 144 | kernel_mmap2, // calls kernel's mmap2, fails if undefined 145 | NULL, // mremap, unused during initialisation 146 | __libc_realloc, // libc realloc 147 | #else 148 | #error This version of ksm_preload has not been tested with your \ 149 | libC. Please define KSMP_FORCE_LIBC to 1 (-DKSMP_FORCE_LIBC=1) and \ 150 | tell me about the result. 151 | #endif 152 | 4096, // page_size 153 | 4096 * 8 // merge threshold 154 | }; 155 | 156 | 157 | 158 | /******** SETUP ********/ 159 | 160 | /* puts()-like, only enabled in DEBUG mode */ 161 | static void 162 | debug_puts (const char *str) 163 | { 164 | #ifdef DEBUG 165 | fprintf (stderr, "ksm_preload: %s\n", str); 166 | #else 167 | (void) str; // disables a warning about unused str 168 | #endif 169 | } 170 | 171 | /* printf()-like, only enabled in DEBUG mode */ 172 | static void 173 | debug_printf (const char *fmt, ...) 174 | { 175 | #ifdef DEBUG 176 | char *strp; 177 | va_list var_args; 178 | va_start (var_args, fmt); 179 | if (vasprintf (&strp, fmt, var_args) > 0) 180 | debug_puts (strp); 181 | else 182 | debug_puts ("debug_printf failed"); 183 | va_end (var_args); 184 | #else 185 | (void) fmt; // disables a warning about unused fmt 186 | #endif 187 | } 188 | 189 | #ifdef GCC 190 | #if __GNUC_PREREQ(4,0) 191 | // marks debug_printf as a printf-like function in order to get warnings 192 | // if it is used incorectly 193 | static void 194 | debug_printf (const char *fmt, ...) 195 | __attribute__ ((format (gnu_printf, 1, 2))); 196 | #endif 197 | #endif 198 | 199 | /* Gets an environment variable from its name and parses it as a 200 | * positive integer. 201 | * Returns the parsed value truncated to INT_MAX, -1 if undefined or invalid. 202 | */ 203 | static int 204 | get_int_from_environment (const char *var_name) 205 | { 206 | char *var_string = getenv (var_name); 207 | char *var_string_end = var_string; 208 | long int var_value; // var_string as a long itn 209 | 210 | if (NULL == var_string) 211 | return -1; 212 | else 213 | var_value = strtol (var_string, &var_string_end, 10); 214 | 215 | /* Validates strtol's return value */ 216 | if (*var_string_end != '\0' || var_value < 0) 217 | { 218 | debug_printf ("Invalid environment variable %s=%s, a" 219 | " positive integer was expected.", var_name, var_string); 220 | return -1; 221 | } 222 | else if (var_value > INT_MAX) 223 | { 224 | debug_printf ("Truncated %s to INT_MAX(%i) ", var_name, INT_MAX); 225 | return INT_MAX; 226 | } 227 | else 228 | return (int) var_value; 229 | } 230 | 231 | /* Just like dlsym but error()s in case of failure */ 232 | static void * 233 | xdlsym (void *handle, const char *symbol) 234 | { 235 | void *res = dlsym (handle, symbol); 236 | if (res) 237 | return res; 238 | else 239 | { 240 | error (1, 0, "failed to load %s : %s", symbol, dlerror ()); 241 | return NULL; 242 | } 243 | } 244 | 245 | /* Sets the globals.* variables */ 246 | static void 247 | setup () 248 | { 249 | int env_merge_treshold; 250 | /* Loads the symbols from the next library using the libc functions 251 | * We will set them at once to avoid a situation where we would be 252 | * using some of them, and some of the default ones 253 | */ 254 | calloc_function *dl_calloc = xdlsym (RTLD_NEXT, "calloc"); 255 | malloc_function *dl_malloc = xdlsym (RTLD_NEXT, "malloc"); 256 | mmap_function *dl_mmap = xdlsym (RTLD_NEXT, "mmap"); 257 | mremap_function *dl_mremap = xdlsym (RTLD_NEXT, "mremap"); 258 | realloc_function *dl_realloc = xdlsym (RTLD_NEXT, "realloc"); 259 | 260 | /* Treats mmap2 as a special case because dlsym fails to find it on 261 | * Ubuntu 10.10, even when it is available. 262 | */ 263 | // TODO(unbrice): investigate... 264 | if (MMAP2_ENABLED) 265 | { 266 | mmap2_function *dl_mmap2 = dlsym (RTLD_NEXT, "mmap2"); 267 | if (NULL != dl_mmap2) 268 | globals.ext_mmap2 = dl_mmap2; 269 | } 270 | 271 | /* Get parameters from the environment */ 272 | globals.page_size = (long unsigned) sysconf (_SC_PAGESIZE); 273 | env_merge_treshold = get_int_from_environment (MERGE_THRESHOLD_ENV_NAME); 274 | if (env_merge_treshold >= 0) 275 | globals.merge_threshold = env_merge_treshold; 276 | 277 | /* Activates the symbols from the next library */ 278 | globals.ext_calloc = dl_calloc; 279 | globals.ext_malloc = dl_malloc; 280 | globals.ext_mmap = dl_mmap; 281 | globals.ext_mremap = dl_mremap; 282 | globals.ext_realloc = dl_realloc; 283 | 284 | debug_puts ("Setup done."); 285 | } 286 | 287 | 288 | /******** UTILITIES FOR WRAPPERS ********/ 289 | 290 | static void 291 | lazily_setup () 292 | { 293 | /* Allows to be sure that only one thread is calling setup() */ 294 | static pthread_mutex_t mutex = PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP; 295 | /* True if setup() has been called and returned */ 296 | static bool setup_done = false; 297 | 298 | /* Quickly returns if the job was already done */ 299 | __sync_synchronize (); // updates globals.* variables 300 | if (likely (setup_done)) 301 | return; 302 | 303 | // 304 | if (pthread_mutex_lock (&mutex) == EDEADLK) 305 | return; // Recursive call 306 | 307 | if (!setup_done) // Might have been called since last check 308 | { 309 | setup (); 310 | setup_done = true; 311 | } 312 | 313 | // 314 | pthread_mutex_unlock (&mutex); 315 | } 316 | 317 | /* Issues a madvise(..., MADV_MERGEABLE) if len is big enough and flags are rights. 318 | * Flags are ignores if flags == -1 319 | */ 320 | static void 321 | merge_if_profitable (void *address, size_t length, int flags) 322 | { 323 | 324 | /* Rounds address to its page */ 325 | const uintptr_t raw_address = (uintptr_t) address; 326 | const uintptr_t page_address = 327 | (raw_address / globals.page_size) * globals.page_size; 328 | assert (page_address <= raw_address); 329 | 330 | /* Computes the new length */ 331 | const size_t new_length = length + (size_t) (raw_address - page_address); 332 | 333 | if (new_length <= globals.merge_threshold || NULL == address) 334 | return; 335 | /* Checks that required flags are present and that forbidden ones are not */ 336 | else if (flags == -1 // flags are unknown 337 | // Checks for required flags, avoids the stacks 338 | || ((flags & MAP_PRIVATE) && (flags & MAP_ANONYMOUS) 339 | && !(flags & MAP_GROWSDOWN) && !(flags & MAP_STACK))) 340 | { 341 | if (0 != madvise ((void *) page_address, new_length, MADV_MERGEABLE)) 342 | debug_puts ("madvise() failed"); 343 | else 344 | debug_puts ("Sharing"); 345 | } 346 | else 347 | debug_puts ("Not sharing (flags filtered)"); 348 | } 349 | 350 | 351 | /******** WRAPPERS ********/ 352 | 353 | /* Just like calloc() but calls merge_if_profitable */ 354 | void * 355 | calloc (size_t nmemb, size_t size) 356 | { 357 | lazily_setup (); 358 | void *res = globals.ext_calloc (nmemb, size); 359 | merge_if_profitable (res, size, -1); 360 | return res; 361 | } 362 | 363 | /* Just like malloc() but calls merge_if_profitable */ 364 | void * 365 | malloc (size_t size) 366 | { 367 | lazily_setup (); 368 | void *res = globals.ext_malloc (size); 369 | merge_if_profitable (res, size, -1); 370 | return res; 371 | } 372 | 373 | /* Just like mmap() but calls merge_if_profitable */ 374 | void * 375 | mmap (void *addr, size_t length, int prot, int flags, int fd, off_t offset) 376 | { 377 | lazily_setup (); 378 | void *res = globals.ext_mmap (addr, length, prot, flags, fd, offset); 379 | merge_if_profitable (res, length, flags); 380 | return res; 381 | } 382 | 383 | #if ! MMAP2_ENABLED 384 | /* Hides mmap2 */ 385 | static void *mmap2 (void *addr, size_t length, int prot, int flags, int fd, 386 | off_t pgoffset) __attribute__ ((unused)); 387 | #endif 388 | 389 | /* Just like mmap2() but calls merge_if_profitable */ 390 | void * 391 | mmap2 (void *addr, size_t length, int prot, int flags, int fd, off_t pgoffset) 392 | { 393 | assert (MMAP2_ENABLED); 394 | lazily_setup (); 395 | void *res = globals.ext_mmap2 (addr, length, prot, flags, fd, pgoffset); 396 | merge_if_profitable (res, length, flags); 397 | return res; 398 | } 399 | 400 | /* Just like mremap() but calls merge_if_profitable */ 401 | void * 402 | mremap (void *old_address, size_t old_length, size_t new_length, int flags, 403 | ...) 404 | { 405 | lazily_setup (); 406 | void *res; 407 | if (flags & MREMAP_FIXED) 408 | { 409 | /* This is the five-arguments version of mremap. */ 410 | // It sometimes happens that the kernel's API is so ugly… 411 | void *target_address; 412 | va_list extra_args; 413 | va_start (extra_args, flags); 414 | target_address = va_arg (extra_args, void *); 415 | va_end (extra_args); 416 | res = globals.ext_mremap (old_address, old_length, new_length, flags, 417 | target_address); 418 | } 419 | else 420 | res = globals.ext_mremap (old_address, old_length, new_length, flags); 421 | merge_if_profitable (res, new_length, -1); 422 | return res; 423 | } 424 | 425 | /* Just like realloc() but calls merge_if_profitable */ 426 | void * 427 | realloc (void *addr, size_t size) 428 | { 429 | lazily_setup (); 430 | void *res = globals.ext_realloc (addr, size); 431 | merge_if_profitable (res, size, -1); 432 | return res; 433 | } 434 | --------------------------------------------------------------------------------