My guess here would be that jiffies_64 is atomic on 64bit platforms,
but not on 32bit platforms.
On 29 Dec 2009, at 4:15 PM, Robert P. J. Day wrote:
from kernel/timer.c:
/*
* The 64-bit jiffies value is not atomic - you MUST NOT read it
* without sampling the sequence number in xtime_lock.
* jiffies is defined in the linker script...
*/
void do_timer(unsigned long ticks)
{
jiffies_64 += ticks;
update_wall_time();
calc_global_load();
}
i'm not sure how to interpret that comment since it clearly suggests
that you can't simply access jiffies_64, but that's exactly what
do_timer() is doing in that first line by incrementing it by a certain
value. can anyone clarify whether the above makes any sense?
rday
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Robert P. J. Day Waterloo, Ontario,
CANADA
Linux Consulting, Training and Kernel Pedantry.
Web page: http://crashcourse.ca
Twitter: http://twitter.com/rpjday
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