Messages in this thread | | | Date | Fri, 18 Apr 2008 08:35:52 -0600 | From | "Chris Friesen" <> | Subject | Re: gettimeofday() in 2.6.24 |
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Jack Harvard wrote: > On Thu, Apr 17, 2008 at 7:13 PM, Chris Friesen <cfriesen@nortel.com> > wrote:
>> system_timer->offset() uses the added timer to return the number of >> usecs since the last timer tick. It's potentially different for >> each specific type of arm blade, and the function often has >> "gettimeoffset" in the name.
>> "xtime" is updated in the core kernel code.
> is "xtime" updated by the time tick clock timer, i.e., the timer > which generates interrupts every 1/HZ second to the kernel. Put it in > another way, does gettimeofday get time in two parts 1) seconds from > xtime.tv_sec, updated by timer0, 2) microseconds from xtime.tv_nsec + > system_timer->offset(), updated by timer0 and timer3.
Yes, I think xtime is updated by the tick timer.
system_timer->offset() may be updated by different mechanisms, depending on the specific arm subarch.
> Do you mean the code here > "http://lxr.linux.no/linux+v2.6.24/kernel/time/timekeeping.c#L45"
No. As I said, the function usually has "gettimeoffset" in the name and it's specific to arm so it would be under arch/arm. For instance, on Xscale boards it's ixp2000_gettimeoffset() in arch/arm/mach-ixp2000/core.c.
For more information you might want to look at the code in arch/arm or else talk to the arm developers on the linux-arm-kernel mailing list.
Chris
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