Messages in this thread | | | Date | Thu, 29 Nov 2007 22:36:21 +0100 | From | Patrick McHardy <> | Subject | Re: constant_tsc and TSC unstable |
| |
H. Peter Anvin wrote: > Paul Rolland (ポール・ロラン) wrote: >> Hello, >> >> I've a machine with a Core2Duo CPU. /proc/cpuinfo reports the flag >> constant_tsc, but at boot time, I have the log : >> >> ... >> Total of 2 processors activated (6919.15 BogoMIPS). >> ENABLING IO-APIC IRQs >> ..TIMER: vector=0x31 apic1=0 pin1=2 apic2=-1 pin2=-1 >> checking TSC synchronization [CPU#0 -> CPU#1]: >> Measured 3978592228 cycles TSC warp between CPUs, turning off TSC clock. >> Marking TSC unstable due to: check_tsc_sync_source failed. >> Brought up 2 CPUs >> ... >> >> This machine is running 2.6.23.1-21.fc7. I know I should report to >> Fedora, >> but I was wondering if this is a bug or a feature ;) >> > > constant_tsc means the TSC doesn't change with CPU core frequency. > > The problem you're having is that the TSCs of your two cores are > completely different, over a second apart. This is a bug, unrelated > to constant_tsc.
On my core2duo I noticed that the TSC of the second core doesn't start counting until the CPU is activated. Since they're not synchronized manually anymore this makes the TSC check fail.
- 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/
| |