Messages in this thread | | | Date | Mon, 9 Jul 2007 16:27:59 +0200 | From | "Alessandro Suardi" <> | Subject | clocksource change of behavior in 2.6.22 compared to 2.6.20 causes massive system clock slowdown |
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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
thanks, ciao,
--alessandro
"Did you get married but forgot to get divorced ?"
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