linux-kernel - clocksource change of behavior in 2.6.22 compared to 2.6.20 causes massive system clock slowdown

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <5a4c581d0707090727q15eff62ax1fdb1271754cc2d2@mail.gmail.com>
Date:	Mon, 9 Jul 2007 16:27:59 +0200
From:	"Alessandro Suardi" <alessandro.suardi@...il.com>
To:	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: clocksource change of behavior in 2.6.22 compared to 2.6.20 causes massive system clock slowdown

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@...key ~]# cd /sys/devices/system/clocksource/clocksource0/
[root@...key clocksource0]# cat available_clocksource
pit jiffies tsc
[root@...key clocksource0]# cat current_clocksource
tsc
[root@...key clocksource0]# uname -a
Linux donkey 2.6.22 #1 PREEMPT Mon Jul 9 13:26:38 CEST 2007 i686
athlon i386 GNU/Linux
[root@...key 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 ?"

     (Danny and Dusty, 'The Good Old Days')
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/