linux高精度时钟分析

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1、linux高精度时钟分析锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛铔愯洂http://qgjie456.blog.163.com/MSN锛歲gjie@hotmail.com鏈枃閫傜敤浜?linux-2.6.22.8V0.1娆㈣繋杞浇锛屼絾璇蜂繚鐣欎綔鑰呬俊鎭?锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛锛婏紛涓€銆佹暟鎹粨鏋勫垎鏋?structhrtimer_clock_base{structhrtimer_

2、cpu_basecpu_base;clockid_tindex;structrb_rootactive;structrb_nodefirst;ktime_tresolution;ktime_t(get_time)(void);ktime_t(get_softirq_time)(void);ktime_tsoftirq_time;#ifdefCONFIG_HIGH_RES_TIMERSktime_toffset;int(reprogram)(structhrtimert,structhrtimer_clock_baseb,ktime_tn);#endif};structhrtimer_

3、cpu_base{spinlock_tlock;structlock_class_keylock_key;structhrtimer_clock_baseclock_base[HRTIMER_MAX_CLOCK_BASES];#ifdefCONFIG_HIGH_RES_TIMERSktime_texpires_next;inthres_active;structlist_headcb_pending;unsignedlongnr_events;#endif};kernel-2.6.22涓殑armarch鍔犲叆浜嗗dynticks,clocksource/event鏀寔.鎵句簡浜

4、沰ernelclock鍙妕imer瀛愮郴缁熻繎鏉ョ殑鍙樺寲,鎬荤粨涓€涓?涓€鑸潵璇碨oft-Timer(timerwheel/hrtimer)閮芥槸鐢盚ardware-Timer(鏃堕挓涓柇涔嬬被)浠ュ強鐩稿叧鐨刢locksource(e.gGPTinSoc)椹卞姩,鎵€浠ユ垜鎵撶畻鍏堜粠clock杩欏眰寮€濮嬩粙缁?鎺ョ潃鏄痵oft-timer,kerneltimekeeping,鏈€鍚庢潵鐪嬩竴浜涘簲鐢?ClockSourceclocksource瀹氫箟浜嗕竴涓猚lockdevice鐨勫熀鏈睘鎬у強琛屼负,杩欎簺clockdevice涓€鑸兘鏈夎鏁?瀹氭椂,浜х敓涓

5、柇鑳藉姏,姣斿GPT.缁撴瀯瀹氫箟濡備笅:structclocksource{charname;structlist_headlist;intrating;cycle_t(read)(void);cycle_tmask;u32mult;/cycle->xtimeinterval,maybetwoclockcycletriggeroneinterrupt(onextimeinterval)/u32shift;unsignedlongflags;cycle_t(vread)(void);void(resume)(void);/timekeepingspecificdata,ignore

6、/cycle_tcycle_interval;/justtherateofGPTcountperOSHZ/u64xtime_interval;/xtime_interval=cycle_intervalmult./cycle_tcycle_last____cacheline_aligned_in_smp;/lastcycleinratecount/u64xtime_nsec;/cyclecount,remainfromxtime.tv_nsecnownsecratecountoffset=xtime_nsec+xtime.tv_nsec<

7、鐨勬垚鍛樻槸read(),cycle_last鍜宑ycle_interval.鍒嗗埆瀹氫箟浜嗚鍙朿lockdevicecount瀵勫瓨鍣ㄥ綋鍓嶈鏁板€兼帴鍙?淇濆瓨涓婁竴娆″懆鏈熻鏁板€煎拰姣忎釜tick鍛ㄦ湡闂撮殧鍊?杩欎釜缁撴瀯鍐呯殑鍊?鏃犺鏄痗ycle_t,杩樻槸u64绫诲瀷(瀹為檯cycle_t灏辨槸u64)閮芥槸璁℃暟鍊?cycle),鑰屼笉鏄痭sec,sec鍜宩iffies.read()鏄暣涓猭ernel璇诲彇绮剧‘鐨勫崟璋冩椂闂磋