Linux Certif

Toute la documentation sur la certification Linux LPI

madvise

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madvise - ¥á¥â¥êÍøÍѤ˴ؤ¹¤ë¥¢¥É¥Ð¥¤¥¹¤òÍ¿¤¨¤ë

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#include <sys/mman.h>

int madvise(void *start, size_t length, int advice);

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madvise() ¥·¥¹¥Æ¥à¥³¡¼¥ë¤Ï¡¢¥¢¥É¥ì¥¹ start ¤«¤é¤Ï¤¸¤Þ¤ë length ¥Ð¥¤¥È¤Î¥á¥â¥ê¥Ö¥í¥Ã¥¯¤Î¥Ú¡¼¥¸¥ó¥°Æþ½ÐÎϤò¤É¤¦°·¤¨¤ÐÎɤ¤¤«¡¢ ¥«¡¼¥Í¥ë¤Ë¥¢¥É¥Ð¥¤¥¹¤¹¤ë¡£ ¤³¤ì¤òÍѤ¤¤ë¤È¡¢ ¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤«¤é¥«¡¼¥Í¥ë¤Ë¡¢ ¥Þ¥Ã¥×¤µ¤ì¤¿¥á¥â¥ê¤ä¶¦Í­¥á¥â¥ê¤ò¤É¤Î¤è¤¦¤Ë°·¤Ã¤Æ¤Û¤·¤¤¤«ÅÁ¤¨¤ë¤³¤È¤¬¤Ç¤­¡¢ ¥«¡¼¥Í¥ë¤Ï¤½¤ì¤Ë±þ¤¸¤ÆÀèÆɤߤ䥭¥ã¥Ã¥·¥å¤Ê¤É¤ÎŬÀڤʼêË¡¤òÁªÂò¤Ç¤­¤ë¡£ ¤³¤Î¥³¡¼¥ë¤Ï¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤ÎÆ°ºî¤½¤Î¤â¤Î¤Ë¤Ï±Æ¶Á¤·¤Ê¤¤ (MADV_DONTNEED ¤Î¾ì¹ç¤ÏÊÌ) ¤¬¡¢ À­Ç½¤Ë¤Ï±Æ¶Á¤·¤¦¤ë¡£ ¤Ê¤ª¤³¤Î¥¢¥É¥Ð¥¤¥¹¤ò¼õ¤±Æþ¤ì¤ë¤«¤É¤¦¤«¤Ï¥«¡¼¥Í¥ë¤ËǤ¤µ¤ì¤ë¡£

¥¢¥É¥Ð¥¤¥¹¤Ï¥Ñ¥é¥á¡¼¥¿ advice ¤Ë¤è¤Ã¤ÆÍ¿¤¨¤ë¡£°Ê²¼¤Î¤¤¤º¤ì¤«¤ò»ØÄê¤Ç¤­¤ë¡£

MADV_NORMAL

ÆÃÊ̤ʰ·¤¤¤Ï¹Ô¤ï¤Ê¤¤¡£¤³¤ì¤¬¥Ç¥Õ¥©¥ë¥È¤Ç¤¢¤ë¡£

MADV_RANDOM

¥Ú¡¼¥¸»²¾È¤Ï¥é¥ó¥À¥à¤Ê½ç½ø¤Ç¹Ô¤ï¤ì¤½¤¦¤À¡£ (¤·¤¿¤¬¤Ã¤Æ¡¢ÀèÆɤߤϤ¢¤Þ¤ê¸ú²Ì¤¬¤Ê¤µ¤½¤¦¤À¡£)

MADV_SEQUENTIAL

¥Ú¡¼¥¸»²¾È¤Ï¥·¡¼¥±¥ó¥·¥ã¥ë¤Ê½ç½ø¤Ç¹Ô¤ï¤ì¤½¤¦¤À¡£ (¤·¤¿¤¬¤Ã¤ÆÍ¿¤¨¤¿ÈϰϤΥڡ¼¥¸¤ÏÀѶËŪ¤ËÀèÆɤߤ·¤Æ¤ª¤¯¤ÈÎɤ¤¤À¤í¤¦¡£ ¤Þ¤¿¥¢¥¯¥»¥¹¤¬½ª¤ï¤Ã¤¿¤é®¤ä¤«¤Ë²òÊü¤·¤ÆÎɤ¤¡£)

MADV_WILLNEED

¶á¤¤¾­Íè¤Ë¥¢¥¯¥»¥¹¤µ¤ì¤½¤¦¤À¡£ (¤·¤¿¤¬¤Ã¤Æ¤³¤ì¤é¤Î¥Ú¡¼¥¸¤òº£¤Î¤¦¤Á¤ËÀèÆɤߤ·¤Æ¤ª¤¯¤È¤¤¤¤¤À¤í¤¦¡£)

MADV_DONTNEED

¤·¤Ð¤é¤¯¥¢¥¯¥»¥¹¤Ï¤Ê¤µ¤½¤¦¤À¡£ (¸½»þÅÀ¤Ç¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤ÏÍ¿¤¨¤¿ÈϰϤνèÍý¤ò½ª¤¨¤Æ¤¤¤ë¡£ ¤·¤¿¤¬¤Ã¤Æ¥«¡¼¥Í¥ë¤Ï¤³¤ì¤Ë´ØÏ¢¤¹¤ë¥ê¥½¡¼¥¹¤ò²òÊü¤·¤ÆÎɤ¤¡£) ¤³¤ì°Ê¹ß¤³¤ÎÈϰϤΥڡ¼¥¸¤Ø¤Î¥¢¥¯¥»¥¹¤¬¤¢¤ë¤È¡¢ À®¸ù¤Ï¤¹¤ë¤¬¡¢¥á¥â¥ê¤ÎÆâÍƤò¥Þ¥Ã¥×¸µ¤Î¥Õ¥¡¥¤¥ë¤«¤é¥í¡¼¥É¤·Ä¾¤¹¤³¤È¤Ë¤Ê¤ë (mmap(2) ¤ò¸«¤è) ¤«¡¢ ¤Þ¤¿¤Ï¸µ¥Õ¥¡¥¤¥ë¤¬¤Ê¤¤¥Þ¥Ã¥×¥Ú¡¼¥¸¤Ç¤Ï ¥¢¥¯¥»¥¹¤¬¤¢¤Ã¤¿¤È¤­¤Ë 0 Ëä¤á¤¬¹Ô¤ï¤ì¤ë¤³¤È¤Ë¤Ê¤ë¡£

MADV_REMOVE (Linux 2.6.16 °Ê¹ß)

»ØÄꤵ¤ì¤¿ÈϰϤΥڡ¼¥¸¤È´ØÏ¢¤¹¤ë¥Ð¥Ã¥­¥ó¥°¥¹¥È¥¢¤ò²òÊü¤¹¤ë¡£ ¸½ºß¤Î¤È¤³¤í¡¢ shmfs/tmpfs ¤À¤±¤¬¤³¤ì¤ËÂбþ¤·¤Æ¤¤¤ë¡£ ¾¤Î¥Õ¥¡¥¤¥ë¥·¥¹¥Æ¥à¤Ç¤Ï -ENOSYS ¤¬ÊÖ¤µ¤ì¤ë¡£

MADV_DONTFORK (Linux 2.6.16 °Ê¹ß)

fork(2) ¤¬¹Ô¤ï¤ì¤¿¸å¡¢»ØÄꤵ¤ì¤¿ÈϰϤΥڡ¼¥¸¤ò»Ò¥×¥í¥»¥¹¤¬ÍøÍѤǤ­¤Ê¤¤¤è¤¦¤Ë¤¹¤ë¡£ ¤³¤Îµ¡Ç½¤Ï¡¢½ñ¤­¹þ¤ß»þ¥³¥Ô¡¼ (copy-on-write) Êý¼°¤Ç¡¢ fork(2) ¤Î¸å¤Ç¿Æ¥×¥í¥»¥¹¤¬¥Ú¡¼¥¸¤Ë½ñ¤­¹þ¤ß¤ò¹Ô¤Ã¤¿¾ì¹ç¤Ë ¥Ú¡¼¥¸¤ÎʪÍý°ÌÃÖ¤¬ÊѲ½¤·¤Ê¤¤¤è¤¦¤Ë¤¹¤ë¤Î¤ËÍ­¸ú¤Ç¤¢¤ë (¥Ú¡¼¥¸¤ÎºÆÇÛÃ֤ϥϡ¼¥É¥¦¥§¥¢¤¬¤½¤Î¥Ú¡¼¥¸¤Ë DMA žÁ÷¤ò¹Ô¤¦¤è¤¦¤Ê¾ì¹ç¤Ë ÌäÂê¤òµ¯¤³¤¹¤³¤È¤¬¤¢¤ë)¡£

MADV_DOFORK (Linux 2.6.16 °Ê¹ß)

MADV_DONTFORK ¤Î±Æ¶Á¤ò¼è¤ê¾Ã¤·¡¢¥Ç¥Õ¥©¥ë¥È¤ÎÆ°ºî¤ËÌ᤹¡£ ¤Ä¤Þ¤ê¡¢ fork(2) ¤ÎÁ°¸å¤Ç¥Þ¥Ã¥Ô¥ó¥°¤Ï·Ñ¾µ¤µ¤ì¤ë¤è¤¦¤Ë¤Ê¤ë¡£

ÊÖ¤êÃÍ

madvise() ¤ÏÀ®¸ù¤¹¤ë¤È 0 ¤òÊÖ¤¹¡£ ¥¨¥é¡¼¤¬µ¯¤³¤ë¤È -1 ¤òÊÖ¤·¡¢ errno ¤òŬÀÚ¤ÊÃͤËÀßÄꤹ¤ë¡£

¥¨¥é¡¼

EAGAIN

²¿¤é¤«¤Î¥«¡¼¥Í¥ë¥ê¥½¡¼¥¹¤¬°ì»þŪ¤ËÍøÍѤǤ­¤Ê¤«¤Ã¤¿¡£

EBADF

»ØÄꤷ¤¿¥Þ¥Ã¥×¤Ï¸ºß¤¹¤ë¤¬¡¢¥Õ¥¡¥¤¥ë¤Ç¤Ï¤Ê¤¤¤È¤³¤í¤ò¥Þ¥Ã¥×¤·¤Æ¤¤¤ë¡£

EINVAL

len ¤ÎÃͤ¬Éé¡¢ start ¤¬¥Ú¡¼¥¸¶­³¦¤Ç¤Ê¤¤¡¢ advice ¤¬Àµ¤·¤¤ÃͤǤʤ¤¡¢ ¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤¬¥í¥Ã¥¯¤µ¤ì¤¿¥Ú¡¼¥¸¤ä¶¦Í­¥Ú¡¼¥¸¤ò (MADV_DONTNEED ¤Ç) ²òÊü¤·¤è¤¦¤È¤·¤Æ¤¤¤ë¡¢¤Ê¤É¡£

EIO

(MADV_WILLNEED ¤Î¾ì¹ç) ¤³¤ÎÈϰϤΥڡ¼¥¸¥ó¥°¤ò¹Ô¤¦¤È¡¢ ¥×¥í¥»¥¹¤Î RSS (resident set size) ¤ÎºÇÂçÃͤò±Û¤¨¤Æ¤·¤Þ¤¦¡£

ENOMEM

(MADV_WILLNEED ¤Î¾ì¹ç) ¥á¥â¥ê¤¬Â­¤ê¤º¡¢¥Ú¡¼¥¸¥ó¥°¤Ë¼ºÇÔ¤·¤¿¡£

ENOMEM

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½àµò

POSIX.1b. POSIX.1-2001 ¤Ç¤Ï¡¢ posix_madvise(3) ¤ò POSIX_MADV_NORMAL ¤Ê¤É¤ÎÄê¿ô¤È¤È¤â¤Ëµ­½Ò¤·¤Æ¤¤¤¿ (¤½¤ì¤¾¤ì¤Î¿¶¤ëÉñ¤¤¤Ï¤³¤³¤Ç½Ò¤Ù¤¿¤â¤Î¤Ë¶á¤¤)¡£ ¥Õ¥¡¥¤¥ë¥¢¥¯¥»¥¹¤ËÂФ·¤Æ¤â posix_fadvise(3) ¤È¤¤¤¦Îà»÷¤Î´Ø¿ô¤¬Â¸ºß¤¹¤ë¡£

MADV_REMOVE, MADV_DONTFORK, MADV_DOFORK ¤Ï Linux ¸ÇÍ­¤Ç¤¢¤ë¡£

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Linux ¤Ç¤ÎÃí°Õ

¸½ºß¤Î Linux ¤Î¼ÂÁõ (2.4.0) ¤Ç¤Ï¡¢ ¤³¤Î¥·¥¹¥Æ¥à¥³¡¼¥ë¤ò¥¢¥É¥Ð¥¤¥¹¤È¤¤¤¦¤è¤ê¤ÏÌ¿Îá¤È¸«¤Æ¤¤¤ë¡£ ¤·¤¿¤¬¤Ã¤Æ¤³¤Î¥¢¥É¥Ð¥¤¥¹¤ËÂФ·¤ÆÄ̾ï¹Ô¤ï¤ì¤ëÆ°ºî¤¬ÉÔ²Äǽ¤Ê¾ì¹ç¤Ï¡¢ ¥¨¥é¡¼¤òÊÖ¤¹¤³¤È¤¬¤¢¤ë (¾åµ­¤Î ¥¨¥é¡¼ ¤Îµ­½Ò¤ò¸«¤è)¡£ ¤³¤Î¿¶Éñ¤¤¤Ïɸ½à¤È¤Ï°Û¤Ê¤ë¡£

Linux ¤Î¼ÂÁõ¤Ç¤Ï start ¤Î¥¢¥É¥ì¥¹¤Ï¥Ú¡¼¥¸¶­³¦¤ÎÃͤǤʤ±¤ì¤Ð¤Ê¤é¤Ê¤¤¡£¤Þ¤¿ length ¤Ï 0 ¤Ç¤¢¤Ã¤Æ¤â¹½¤ï¤Ê¤¤¡£ ¤Þ¤¿ Linux ÈǤΠmadvise() ¤Ç¤Ï¡¢»ØÄꤵ¤ì¤¿¥¢¥É¥ì¥¹ÈϰϤ˥ޥåפµ¤ì¤Æ¤¤¤Ê¤¤Éôʬ¤¬¤¢¤ë¤È¡¢ ¤³¤ì¤é¤ò̵»ë¤·¤Æ»Ä¤ê¤ÎÉôʬ¤Ë¥¢¥É¥Ð¥¤¥¹¤òŬÍѤ¹¤ë (¤·¤«¤·¥·¥¹¥Æ¥à¥³¡¼¥ë¤ËÂФ·¤Æ¤Ï¤Á¤ã¤ó¤È ENOMEM ¤òÊÖ¤¹)¡£

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getrlimit(2), mincore(2), mmap(2), mprotect(2), msync(2), munmap(2)