Linux Certif

Toute la documentation sur la certification Linux LPI

time

̾Á°

time - »þ´Ö¤Î³µÍ×

ÀâÌÀ

¼Â»þ´Ö (real time) ¤È¥×¥í¥»¥¹»þ´Ö

¼Â»þ´Ö¤Ï¡¢ÆÃÄê¤Î»þÅÀ¤«¤é·×¤Ã¤¿»þ´Ö¤ÈÄêµÁ¤µ¤ì¤ë¡£ ÆÃÄê¤Î»þÅÀ¤È¤Ï¡¢²áµî¤Îɸ½àŪ¤Ê»þÅÀ (²¼µ­¤Îµª¸µ (Epoch) ¤È¥«¥ì¥ó¥À»þ¹ï¤ÎÀâÌÀ¤ò»²¾È) ¤ä¡¢ ¥×¥í¥»¥¹¤Î°ìÀ¸¤Ë¤ª¤±¤ë²¿¤é¤«¤Î»þÅÀ (Î㤨¤Ð¡¢³«»Ï»þ) ¤Ç¤¢¤ë (·Ð²á»þ´Ö)¡£

¥×¥í¥»¥¹»þ´Ö¤Ï¡¢¥×¥í¥»¥¹¤Ë¤è¤Ã¤Æ»È¤ï¤ì¤¿Áí CPU »þ´Ö¤ÈÄêµÁ¤µ¤ì¤ë¡£ ¿¤¯¤Î¾ì¹ç¡¢¥æ¡¼¥¶»þ´Ö¤È¥·¥¹¥Æ¥à»þ´Ö¤Ëʬ¤±¤é¤ì¤ë¡£ ¥æ¡¼¥¶ CPU »þ´Ö¤Ï¡¢¥³¡¼¥É¤ò¥æ¡¼¥¶¥â¡¼¥É¤Ç¼Â¹Ô¤¹¤ë¤Î¤Ë»È¤Ã¤¿»þ´Ö¤Ç¤¢¤ë¡£ ¥·¥¹¥Æ¥à CPU »þ´Ö¤Ï¡¢¤½¤Î¥×¥í¥»¥¹¤Î¤¿¤á¤Ë ¥«¡¼¥Í¥ë¤¬¥·¥¹¥Æ¥à¥â¡¼¥É¤Ç¼Â¹Ô¤¹¤ë¤Î¤Ë»È¤Ã¤¿»þ´Ö¤Ç¤¢¤ë (Î㤨¤Ð¡¢¥·¥¹¥Æ¥à¥³¡¼¥ë¤ò¼Â¹Ô¤¹¤ë¤Î¤Ë»È¤Ã¤¿»þ´Ö)¡£ time(1) ¥³¥Þ¥ó¥É¤Ï¥×¥í¥°¥é¥à¤Î¼Â¹Ô¤ËÈñ¤µ¤ì¤¿Áí CPU »þ´Ö¤ò·×¤ë¤Î¤Ë»ÈÍѤµ¤ì¤ë¡£ ¥×¥í¥°¥é¥à¤Ï¡¢¼«¿È¤¬Èñ¤·¤¿Áí CPU »þ´Ö¤ò times(2), getrusage(2), clock(3) ¤ò»È¤Ã¤Æ·×¤ë¤³¤È¤¬¤Ç¤­¤ë¡£

¥Ï¡¼¥É¥¦¥§¥¢¥¯¥í¥Ã¥¯

¿¤¯¤Î¥³¥ó¥Ô¥å¡¼¥¿¤¬ (ÅÅÃӤǶîÆ°¤µ¤ì¤ë) ¥Ï¡¼¥É¥¦¥§¥¢¥¯¥í¥Ã¥¯¤ò»ý¤Ã¤Æ¤¤¤ë¡£ ¥«¡¼¥Í¥ë¤Ïµ¯Æ°»þ¤Ë¥½¥Õ¥È¥¦¥§¥¢¥¯¥í¥Ã¥¯¤ò½é´ü²½¤¹¤ë¤¿¤á¤Ë ¥Ï¡¼¥É¥¦¥§¥¢¥¯¥í¥Ã¥¯¤òÆɤ߹þ¤à¡£ ¤è¤ê¾Ü¤·¤¤¾ðÊó¤Ï¡¢ rtc(4) ¤È hwclock(8) ¤ò»²¾È¤¹¤ë¤³¤È¡£

¥½¥Õ¥È¥¦¥§¥¢¥¯¥í¥Ã¥¯, HZ, Jiffy

¿¤¯¤Î¥·¥¹¥Æ¥à¥³¡¼¥ë¤È¥¿¥¤¥à¥¹¥¿¥ó¥×¤ÎÀºÅ٤ϡ¢ ¥½¥Õ¥È¥¦¥§¥¢¥¯¥í¥Ã¥¯¤Îʬ²òǽ¤ËÀ©¸Â¤µ¤ì¤ë¡£ ¥½¥Õ¥È¥¦¥§¥¢¥¯¥í¥Ã¥¯¤Ï¥«¡¼¥Í¥ë¤Ë¤è¤Ã¤Æ´ÉÍý¤µ¤ì¡¢ »þ´Ö¤ò jiffy ñ°Ì¤Ç·×¤ë¡£ jiffy ¤ÎÂ礭¤µ¤Ï¥«¡¼¥Í¥ëÄê¿ô HZ ¤ÎÃͤǷèÄꤵ¤ì¤ë¡£ HZ ¤ÎÃͤϥ«¡¼¥Í¥ë¤Î¥Ð¡¼¥¸¥ç¥ó¤È¥Ï¡¼¥É¥¦¥§¥¢¥×¥é¥Ã¥È¥Õ¥©¡¼¥à¤Ç°Û¤Ê¤ë¡£ x86 ¤Î¾ì¹ç¤Ï°Ê²¼¤ÎÄ̤ê¤Ç¤¢¤ë: 2.4.x ¤È¤½¤ì¤è¤êÁ°¤Î¥«¡¼¥Í¥ë¤Ç¤Ï¡¢HZ ¤Ï 100 ¤Ç¤¢¤Ã¤¿¤Î¤Ç¡¢ jiffy ¤ÎÃÍ¤Ï 0.01 ÉäˤʤäƤ¤¤¿¡£ 2.6.0 °Ê¹ß¤Ç¤Ï¡¢HZ ¤Ï 1000 ¤ËÁý¤ä¤µ¤ì¤¿¤Î¤Ç¡¢jiffy ¤ÎÃÍ¤Ï 0.001 ÉäǤ¢¤ë¡£ ¥«¡¼¥Í¥ë 2.6.13 °Ê¹ß¤Ç¤Ï¡¢HZ ¤ÎÃͤϥ«¡¼¥Í¥ëÀßÄê¥Ñ¥é¥á¡¼¥¿¤Ë¤Ê¤ê¡¢ 100, 250 (¥Ç¥Õ¥©¥ë¥È), 1000 ¤È¤¤¤¦ÃͤˤǤ­¤ë¡£ ¤½¤ì¤¾¤ì jiffy ¤ÎÃÍ¤Ï 0.01, 0.004, 0.001 Éäˤʤ롣 ¥«¡¼¥Í¥ë 2.6.20 °Ê¹ß¤Ç¤Ï¡¢300 ¤âÍøÍѤǤ­¤ë¤è¤¦¤Ë¤Ê¤Ã¤Æ¤¤¤ë¡£ 300 ¤Ï°ìÈÌŪ¤Ê±ÇÁü¥Õ¥ì¡¼¥à¥ì¡¼¥È¤Î¸øÇÜ¿ô¤Ç¤¢¤ë (PAL, 25HZ; NTSC, 30HZ)¡£

µª¸µ

Unix ¥·¥¹¥Æ¥à¤Ï»þ¹ï¤òµª¸µ¤«¤é¤ÎÉÿô¤Çɽ¸½¤¹¤ë¡£ µª¸µ¤Ï 1970 ǯ 1 ·î 1 Æü¤ÎÄ« 0:00:00 UTC ¤ÇÄêµÁ¤µ¤ì¤ë¡£

¥×¥í¥°¥é¥à¤Ï¥«¥ì¥ó¥À»þ¹ï¤ò gettimeofday(2) ¤ò»È¤Ã¤Æ·×¤ë¤³¤È¤¬¤Ç¤­¤ë¡£ ¤³¤Î´Ø¿ô¤Ïµª¸µ¤«¤é¤Î·Ð²á»þ´Ö¤ò (Éäȥޥ¤¥¯¥íÉäÇ) ÊÖ¤¹¡£ time(2) ¤ÏƱÍͤξðÊó¤òÄ󶡤¹¤ë¤¬¡¢ºÇ¤â¶á¤¤ÉäÎÀºÅÙ¤·¤«¤Ê¤¤¡£ ¥·¥¹¥Æ¥à»þ¹ï¤Ï settimeofday(2) ¤ÇÊѹ¹¤Ç¤­¤ë¡£

Í×ÁÇÊ̤λþ¹ï

¥é¥¤¥Ö¥é¥ê´Ø¿ô¤ÎÃæ¤Ë¤Ï tm ·¿¤Î¹½Â¤ÂΤò»È¤¦¤â¤Î¤¬¤¢¤ë¡£ ¤³¤Î¹½Â¤ÂΤÏÍ×ÁÇÊ̤λþ¹ï¤òɽ¤·¡¢ »þ¹ï¤ÎÃͤòÊÌ¡¹¤ÎÍ×ÁÇ (ǯ¡¦·î¡¦Æü¡¦»þ¡¦Ê¬¡¦ÉäʤÉ) ¤Ëʬ¤±¤Æ³ÊǼ¤¹¤ë¡£ ¤³¤Î¹½Â¤ÂÎ¤Ï ctime(3) ¤Ëµ­½Ò¤µ¤ì¤Æ¤ª¤ê¡¢¥«¥ì¥ó¥À»þ¹ï¤òÍ×ÁÇÊ̤λþ¹ï¤ËÊÑ´¹¤¹¤ë ´Ø¿ô¤Ë¤Ä¤¤¤Æ¤âµ­½Ò¤µ¤ì¤Æ¤¤¤ë¡£ Í×ÁÇÊ̤λþ¹ï¤òɽ¼¨²Äǽ¤Êʸ»úÎó¤ËÊÑ´¹¤¹¤ë´Ø¿ô¤Ë¤Ä¤¤¤Æ¤Ï¡¢ ctime(3), strftime(3), strptime(3) ¤Ëµ­½Ò¤µ¤ì¤Æ¤¤¤ë¡£

¥¿¥¤¥Þ¤Î¥¹¥ê¡¼¥×¤ÈÀßÄê

ÍÍ¡¹¤Ê¥·¥¹¥Æ¥à¥³¡¼¥ë¤È´Ø¿ô¤Ë¤è¤ê¡¢»ØÄꤵ¤ì¤¿°ìÄê¤Î»þ´Ö¡¢ ¥×¥í¥°¥é¥à¤Ï¥¹¥ê¡¼¥× (¼Â¹Ô¤òÄä»ß) ¤¹¤ë¤³¤È¤¬²Äǽ¤Ç¤¢¤ë¡£ nanosleep(2) ¤È sleep(3) ¤ò»²¾È¤¹¤ë¤³¤È¡£

ÍÍ¡¹¤Ê¥·¥¹¥Æ¥à¥³¡¼¥ë¤Ë¤è¤ê¡¢¥×¥í¥»¥¹¤Ï¾­Íè¤Î¤¢¤ë»þÅÀ¤Ç Í­¸ú´ü´Ö¤¬½ªÎ»¤¹¤ë¥¿¥¤¥Þ¤òÀßÄê¤Ç¤­¤ë¡£ ¤Þ¤¿¥ª¥×¥·¥ç¥ó¤È¤·¤Æ·«¤êÊÖ¤·´Ö³Ö¤¬»ØÄê¤Ç¤­¤ë¤â¤Î¤â¤¢¤ë¡£ alarm(2), getitimer(2), timer_create(3) ¤ò»²¾È¤¹¤ë¤³¤È¡£

´ØÏ¢¹àÌÜ

date(1), time(1), adjtimex(2), alarm(2), getitimer(2), getrlimit(2), getrusage(2), gettimeofday(2), nanosleep(2), stat(2), time(2), times(2), utime(2), adjtime(3), clock(3), sleep(3), ctime(3), strftime(3), strptime(3), usleep(3), rtc(4), hwclock(8)