Linux Certif

Toute la documentation sur la certification Linux LPI

posix_fadvise

̾Á°

posix_fadvise - ¥Õ¥¡¥¤¥ë¥Ç¡¼¥¿¤Î¥¢¥¯¥»¥¹¥Ñ¥¿¡¼¥ó¤ò¤¢¤é¤«¤¸¤áÀë¸À¤¹¤ë

½ñ¼°

#define _XOPEN_SOURCE 600

#include <fcntl.h>



int posix_fadvise(int fd, off_t offset, off_t len, int advice);

ÀâÌÀ

¥×¥í¥°¥é¥à¤Ï¡¢¾­ÍèÆÃÄê¤Î¥Ñ¥¿¡¼¥ó¤Ç¥Õ¥¡¥¤¥ë¥Ç¡¼¥¿¤Ë ¥¢¥¯¥»¥¹¤¹¤ë°Õ»×¤òÅÁ¤¨¤ë¤¿¤á¤Ë posix_fadvise() ¤ò»È¤¦¤³¤È¤¬¤Ç¤­¤ë¡£ ¤³¤ì¤Ë¤è¤ê¡¢¥«¡¼¥Í¥ë¤¬Å¬ÀڤʺÇŬ²½¤ò¼Â¹Ô¤¹¤ë¤³¤È¤¬²Äǽ¤Ë¤Ê¤ë¡£

advice ¤Ï fd ¤¬»²¾È¤·¤Æ¤¤¤ë¥Õ¥¡¥¤¥ë¤Î offset ¤«¤é»Ï¤Þ¤ë len ¥Ð¥¤¥È¤ÎÈÏ°ÏÆâ (len ¤¬ 0 ¤Î¾ì¹ç¤Ï¥Õ¥¡¥¤¥ë¤Î½ª¤ê¤Þ¤Ç) ¤Î (ɬ¤º¤·¤â¸ºß¤·¤Ê¤¤) Îΰè¤ËŬÍѤµ¤ì¤ë¡£ ¥¢¥É¥Ð¥¤¥¹¤ÏµÁ̳¤Å¤±¤Ç¤Ï¤Ê¤¤¡£ ¥¢¥É¥Ð¥¤¥¹¤Ïñ¤Ë¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤Î¤¿¤á¤Ë²ÄǽÀ­¤ò¹½À®¤¹¤ë¤À¤±¤Ç¤¢¤ë¡£

advice ¤Ëµö¤µ¤ì¤ëÃͤˤϡ¢°Ê²¼¤Î¤â¤Î¤¬´Þ¤Þ¤ì¤ë:

POSIX_FADV_NORMAL

»ØÄꤵ¤ì¤¿¥Ç¡¼¥¿¤Î¥¢¥¯¥»¥¹¥Ñ¥¿¡¼¥ó¤ò»Ø¼¨¤¹¤ë¥¢¥É¥Ð¥¤¥¹¤ò ¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤¬²¿¤â»ý¤Ã¤Æ¤¤¤Ê¤¤¤³¤È¤ò¼¨¤¹¡£ ¥ª¡¼¥×¥ó¤µ¤ì¤¿¥Õ¥¡¥¤¥ë¤Ë¥¢¥É¥Ð¥¤¥¹¤¬»ØÄꤵ¤ì¤Ê¤¤¾ì¹ç¡¢ ¤³¤ì¤¬¥Ç¥Õ¥©¥ë¥È¤Ç²¾Äꤵ¤ì¤ë¡£

POSIX_FADV_SEQUENTIAL

¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤Ï»ØÄꤵ¤ì¤¿¥Ç¡¼¥¿¤¬¥·¡¼¥±¥ó¥·¥ã¥ë¤Ë (Â礭¤Ê¥ª¥Õ¥»¥Ã¥È¤ÎÁ°¤Ë¾®¤µ¤Ê¥ª¥Õ¥»¥Ã¥È¤Î¥Ç¡¼¥¿¤òÆɤà¤è¤¦¤Ë) ¥¢¥¯¥»¥¹¤µ¤ì¤ë¤³¤È¤ò´üÂÔ¤¹¤ë¡£

POSIX_FADV_RANDOM

»ØÄꤵ¤ì¤¿¥Ç¡¼¥¿¤¬¥é¥ó¥À¥à¤Ê½çÈ֤ǥ¢¥¯¥»¥¹¤µ¤ì¤ë¡£

POSIX_FADV_NOREUSE

»ØÄꤵ¤ì¤¿¥Ç¡¼¥¿¤Ï 1 ÅÙ¤·¤«¥¢¥¯¥»¥¹¤µ¤ì¤Ê¤¤¡£

POSIX_FADV_WILLNEED

»ØÄꤵ¤ì¤¿¥Ç¡¼¥¿¤Ï¶á¤¤¾­Í襢¥¯¥»¥¹¤µ¤ì¤ë¡£

POSIX_FADV_DONTNEED

»ØÄꤵ¤ì¤¿¥Ç¡¼¥¿¤Ï¶á¤¤¾­Í襢¥¯¥»¥¹¤µ¤ì¤Ê¤¤¡£

ÊÖ¤êÃÍ

À®¸ù¤·¤¿¾ì¹ç¤Ï 0 ¤¬ÊÖ¤µ¤ì¤ë¡£ ¼ºÇÔ¤·¤¿¾ì¹ç¤Ï¥¨¥é¡¼Èֹ椬ÊÖ¤µ¤ì¤ë¡£

¥¨¥é¡¼

EBADF

fd °ú¤­¿ô¤¬Í­¸ú¤Ê¥Õ¥¡¥¤¥ë¥Ç¥£¥¹¥¯¥ê¥×¥¿¤Ç¤Ê¤¤¡£

EINVAL

̵¸ú¤ÊÃͤ¬ advice ¤Ë»ØÄꤵ¤ì¤¿¡£

ESPIPE

»ØÄꤵ¤ì¤¿¥Õ¥¡¥¤¥ë¥Ç¥£¥¹¥¯¥ê¥×¥¿¤¬¥Ñ¥¤¥×¤Þ¤¿¤Ï FIFO ¤ò»²¾È¤·¤Æ¤¤¤ë (¤³¤Î¾ì¹ç¡¢Linux ¤Ï¼ÂºÝ¤Ë¤Ï EINVAL ¤òÊÖ¤¹)¡£

¥Ð¡¼¥¸¥ç¥ó

posix_fadvise() ¤Ï¥«¡¼¥Í¥ë 2.5.60 ¤ÇÅо줷¤¿¡£

½àµò

POSIX.1-2001. len °ú¤­¿ô¤Î·¿¤¬ POSIX.1-2003 TC1 ¤Ë¤ª¤¤¤Æ size_t ¤«¤é off_t ¤ËÊѹ¹¤µ¤ì¤¿ÅÀ¤ËÃí°Õ¤¹¤ë¤³¤È¡£

Ãí°Õ

Linux ¤Ç¤Ï¡¢POSIX_FADV_NORMAL ¤Ï¥Ð¥Ã¥­¥ó¥°¥Ç¥Ð¥¤¥¹¤Î ¥Ç¥Õ¥©¥ë¥È¥µ¥¤¥º¤ËÀèÆÉ¤ß (readahead) ¥¦¥¤¥ó¥É¥¦¤òÀßÄꤹ¤ë¡£ POSIX_FADV_SEQUENTIAL ¤Ï¤³¤Î¥µ¥¤¥º¤ò 2 Çܤ·¡¢ POSIX_FADV_RANDOM ¤ÏÀèÆɤߤòÁ´¤¯Ìµ¸ú¤Ë¤¹¤ë¡£ ¤³¤ì¤é¤ÎÊѹ¹¤Ï¥Õ¥¡¥¤¥ëÁ´ÂΤ˱ƶÁ¤·¡¢»ØÄꤵ¤ì¤¿Îΰè¤Î¤ß¤Ë±Æ¶Á¤¹¤ë¤ï¤±¤Ç¤Ï¤Ê¤¤ (¤·¤«¤·Æ±¤¸¥Õ¥¡¥¤¥ë¤ËÂФ¹¤ë¾¤Î¥ª¡¼¥×¥ó¥Õ¥¡¥¤¥ë¥Ï¥ó¥É¥ë¤Ï±Æ¶Á¤ò¼õ¤±¤Ê¤¤)¡£

POSIX_FADV_WILLNEED ¤Ï¡¢ ¥Ú¡¼¥¸¥­¥ã¥Ã¥·¥å¤Ë»ØÄêÎΰè¤Î¥Ö¥í¥Ã¥¯¤µ¤ì¤Ê¤¤Æɤ߹þ¤ß¤ò³«»Ï¤¹¤ë¡£ Æɤ߹þ¤Þ¤ì¤ë¥Ç¡¼¥¿¤ÎÁíÎ̤ϡ¢ ²¾ÁÛ¥á¥â¥ê¤ÎÉé²Ù¤Ë°Í¤Ã¤Æ¥«¡¼¥Í¥ë¤¬¸º¤é¤¹¤«¤â¤·¤ì¤Ê¤¤ (¿ô¥á¥¬¥Ð¥¤¥È¤Ç¤¢¤ì¤ÐÄ̾ï¤ÏÁ´¤¯½½Ê¬¤Ç¤¢¤ê¡¢ ¤½¤ì¤è¤ê¿¤¯¤Æ¤â¤á¤Ã¤¿¤ËÌò¤ËΩ¤¿¤Ê¤¤)¡£

2.6.18 ¤è¤êÁ°¤Î¥«¡¼¥Í¥ë¤Ç¤Ï¡¢POSIX_FADV_NOREUSE ¤Ï POSIX_FADV_WILLNEED ¤ÈƱ¤¸°ÕÌ£¤Ç¤¢¤Ã¤¿¡£ ¤³¤ì¤Ï¿ʬ¥Ð¥°¤Ç¤¢¤Ã¤¿¡£ ¥«¡¼¥Í¥ë 2.6.18 °Ê¹ß¤Ç¤Ï¡¢¤³¤Î¥Õ¥é¥°¤Ï²¿¤â¹Ô¤ï¤Ê¤¤¡£

POSIX_FADV_DONTNEED ¤Ï»ØÄꤵ¤ì¤¿Îΰè¤Ë´ØÏ¢ÉÕ¤±¤é¤ì¤¿ ¥­¥ã¥Ã¥·¥å¥Ú¡¼¥¸¤ò²òÊü¤·¤è¤¦¤È¤¹¤ë¡£ Î㤨¤Ð¡¢¤³¤ì¤ÏÂ礭¤Ê¥Õ¥¡¥¤¥ë¤ò¥¹¥È¥ê¡¼¥ß¥ó¥°¤¹¤ë¤È¤­¤ËÌòΩ¤Ä¡£ ¥×¥í¥°¥é¥à¤Ï¡¢»ÈÍѺѤߤΥ­¥ã¥Ã¥·¥å¤µ¤ì¤¿¥Ç¡¼¥¿¤ò²òÊü¤¹¤ë¤è¤¦¤Ë¡¢ Äê´üŪ¤Ë¥«¡¼¥Í¥ë¤ËÍ׵᤹¤ë¤«¤â¤·¤ì¤Ê¤¤¡£ ¤½¤¦¤¹¤ë¤³¤È¤Ë¤è¤ê¡¢¤µ¤é¤ËÍ­¸ú¤Ê¥­¥ã¥Ã¥·¥å¤µ¤ì¤¿¥Ú¡¼¥¸¤¬¡¢ Âå¤ï¤ê¤ËÇË´þ¤µ¤ì¤ë¤³¤È¤Ï¤Ê¤¤¡£

¤Þ¤À½ñ¤­½Ð¤µ¤ì¤Æ¤¤¤Ê¤¤¥Ú¡¼¥¸¤Ï±Æ¶Á¤ò¼õ¤±¤Ê¤¤¤Î¤Ç¡¢ ¤½¤Î¥Ú¡¼¥¸¤Î²òÊü¤¬Êݾڤµ¤ì¤ë¤³¤È¤ò¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤¬Ë¾¤ó¤Ç¤¤¤ë¤Ê¤é¡¢ ºÇ½é¤Ë fsync(2) ¤Þ¤¿¤Ï fdatasync(2) ¤ò¸Æ¤Ö¤Ù¤­¤Ç¤¢¤ë¡£

¥Ð¥°

2.6.6 ¤è¤êÁ°¤Î¥«¡¼¥Í¥ë¤Ç¤Ï¡¢ len ¤Ë 0 ¤¬»ØÄꤵ¤ì¤¿¾ì¹ç¡¢ ¡Ö¥Õ¥¡¥¤¥ë¤Î½ª¤ê¤Þ¤Ç¤ÎÁ´¤Æ¤Î¥Ð¥¤¥È¡×¤È¤¤¤¦°ÕÌ£¤Ç¤Ï¤Ê¤¯¡¢ ʸ»úÄ̤ê¡Ö0 ¥Ð¥¤¥È¡×¤È¤·¤Æ²ò¼á¤µ¤ì¤Æ¤¤¤¿¡£

´ØÏ¢¹àÌÜ

posix_madvise(2), readahead(2), posix_fallocate(3), feature_test_macros(7)