Messages in this thread | | | Date | Tue, 10 Jul 2007 00:29:35 -0700 | From | Andrew Morton <> | Subject | Re: clocksource change of behavior in 2.6.22 compared to 2.6.20 causes massive system clock slowdown |
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On Mon, 9 Jul 2007 16:27:59 +0200 "Alessandro Suardi" <alessandro.suardi@gmail.com> wrote:
> My oldish AMD K7-800's clock began falling behind after > rebooting from 2.6.20 (and 109 days uptime with a spotless > clock) into 2.6.22; time lost is about four minutes each hour. > > Turns out that 2.6.22 marks my TSC as unstable and starts > using PIT instead. Rebooting 2.6.22 with clocksource=tsc > gets the original stable system time back. > > Not sure whether this is supposed to be the default way of > fixing the issue on older machines, though; if anyone sees > a problem with this, I'm up for providing more information. > > [root@donkey ~]# cd /sys/devices/system/clocksource/clocksource0/ > [root@donkey clocksource0]# cat available_clocksource > pit jiffies tsc > [root@donkey clocksource0]# cat current_clocksource > tsc > [root@donkey clocksource0]# uname -a > Linux donkey 2.6.22 #1 PREEMPT Mon Jul 9 13:26:38 CEST 2007 i686 > athlon i386 GNU/Linux > [root@donkey clocksource0]# cat /proc/cpuinfo > processor : 0 > vendor_id : AuthenticAMD > cpu family : 6 > model : 4 > model name : AMD Athlon(tm) Processor > stepping : 2 > cpu MHz : 800.068 > cache size : 256 KB > fdiv_bug : no > hlt_bug : no > f00f_bug : no > coma_bug : no > fpu : yes > fpu_exception : yes > cpuid level : 1 > wp : yes > flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca > cmov pat pse36 mmx fxsr syscall mmxext 3dnowext 3dnow > bogomips : 1603.17 > clflush size : 32 >
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