I am not clear with the logic of init/calibrate.c http://lxr.ncu.cc/source/init/calibrate.c from line 45 it mentions the following comment. /* 045 * A simple loop like 046 * while ( jiffies < start_jiffies+1) 047 * start = read_current_timer(); 048 * will not do. As we don't really know whether jiffy switch 049 * happened first or timer_value was read first. And some asynchronous 050 * event can happen between these two events introducing errors in lpj. 051 * 052 * So, we do 053 * 1. pre_start <- When we are sure that jiffy switch hasn't happened 054 * 2. check jiffy switch 055 * 3. start <- timer value before or after jiffy switch 056 * 4. post_start <- When we are sure that jiffy switch has happened 057 * 058 * Note, we don't know anything about order of 2 and 3. 059 * Now, by looking at post_start and pre_start difference, we can 060 * check whether any asynchronous event happened or not 061 */ I am not clear with why is that pre_start condition being checked.How is happening of jiffy switch here affecting the logic of the calibrate.c and why is it important? -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
