Messages in this thread Patch in this message | | | Date | Wed, 11 Jun 2003 22:41:44 +0200 | From | Vojtech Pavlik <> | Subject | Re: [PATCH] New x86_64 time code for 2.5.70 |
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On Wed, Jun 11, 2003 at 11:50:32AM -0700, Bryan O'Sullivan wrote:
> The time code for x86-64 in 2.5.70 isout of date and wildly unstable, > setting the clock to the year 1,115,117 (!) during boot about 60% of the > time. This subsequently causes other pieces of completely unrelated > userspace software to crash randomly for no obvious reason once the > system comes up. > > I've forward-ported Vojtech's time code from 2.4, fixing some locking > along the way. The new code supports using the AMD8111 HPET for time > calculations. It also works stably with the PIT/TSC on every boot, > which is the source of the time problems in current 2.5.
Thanks a lot for your work!
> Right now, the only known problem is with the fixup of jiffies if a > timer interrupt is lost, which I've hence turned off. There's > preliminary support for using HPET for the gettimeofday vsyscall, but > since vsyscalls are disabled on x86-64 for now, that's obviously > untested.
This is interesting. I'll have to test why the number of lost tick is computed incorrectly ....
> --- linux-2.5/arch/x86_64/Kconfig 2003-06-11 11:43:09.000000000 -0700 > +++ x86-64-2.5/arch/x86_64/Kconfig 2003-06-11 10:39:45.000000000 -0700 > @@ -52,6 +52,18 @@ > klogd/syslogd or the X server. You should normally N here, unless > you want to debug such a crash. > > +config HPET_TIMER > + bool > + default n > + help > + Use the IA-PC HPET (High Precision Event Timer) to manage > + time in preference to the PIT and RTC, if a HPET is > + present. The HPET provides a stable time base on SMP > + systems, unlike the RTC, but it is more expensive to access,
... probably that should be 'unlike the TSC'? Since RTC does provide a stable time base on a SMP system, and is very far off chip, too.
> + as it is off-chip. You can find the HPET spec at > + <http://www.intel.com/labs/platcomp/hpet/hpetspec.htm>. > + > + If unsure, say Y. > > config GENERIC_ISA_DMA > bool >
-- Vojtech Pavlik SuSE Labs, SuSE CR - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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