[lkml]   [2009]   [Jul]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Subjectjiffies got lost because of printk

Hi there,
We found that system time is not synced with RTC time on our embedded
This is because sometimes we print too many chars to console.
For these lines in the function, release_console_sem, of printk.c,
for ( ; ; ) {
spin_lock_irqsave(&logbuf_lock, flags);
wake_klogd |= log_start - log_end;
if (con_start == log_end)
break; /* Nothing to print */
_con_start = con_start;
_log_end = log_end;
con_start = log_end; /* Flush */
call_console_drivers(_con_start, _log_end);

Interrupt will be disabled before calling call_console_drivers and enabled
after call_console_drivers finishes.
For the setting of com port baud rate 115200 and HZ 100, if there are more
than 115200/8/100 bytes waiting for output,
interrupt will be disabled for more than 1 HZ and timer interrupt will be
I know that printing too much in kernel level is not proper. But for 1000HZ,
interrupt may be lost even just output 15 chars.
Any idea?


 \ /
  Last update: 2009-07-14 13:47    [W:0.057 / U:7.488 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site