Hsieh Steve wrote: > and I found the jiffies is set to -300*HZ as its initial value--> why?? So that it rolls over after 5 min, for testing. > furthermore, I found a new varaible jiffies_64 is added, > I see jiffies_u64++ in do_timer() (HW timer ISR), but see NO jiffies++ > in do_timer(), just as the case in linux2.4? > Why? > what relationship between jiffies and jiffies_64? >From the comment just above do_timer(): http://lxr.linux.no/source/kernel/timer.c#L914 */"jiffies is defined in the linker script..." /* >From system.map: [mali@scox linux-2.6]$ grep "\bjiffies" System.map c02fb000 D jiffies c02fb000 D jiffies_64 c0334fe8 b jiffies_p.2 They point to the same location but on 32 bit architectures 'jiffies' only holds the least significant 32 bits of 'jiffies_64'. Also note that accessing jiffies_64 is not necessarily atomic and special measures must be taken - as mentioned in the same comment. --- fm */ /* -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
