Hi all! On Tuesday 26 August 2008, Daniel Kahn Gillmor wrote: > Hey folks-- > ... > Why would the number jump from 0 to 42949372.96? I can't help but > notice that this is exactly 2^32 - 30000 jiffies, if a jiffy is > 1/100th of a second. It looks like some internal unsigned jiffy > counter is overflowing somehow, or being rolled backward by 30000 > jiffies. What does this mean? It seems to me like this is going to > cause an internal counter overflow 300 seconds after boot. This does > not happen on an x86 system i've got running 2.6.26-1-686.
This seems strange, but this is normal behaviour. When booting, the time is set to zero before jiffies are initialized (tick timer). jiffies are initialized to -5 minutes (5*60*HZ). The jiffies counter *will* overflow after 5 minutes, for verifying that there is no overflow problems with jiffies. However, I can't explain why we don't see that on x86. Perhaps the timer are initialized sooner, but this should be verified. > > 0 igor:~# head -n20 /var/log/kern.log > Aug 26 16:21:25 igor kernel: Kernel logging (proc) stopped. > Aug 26 16:21:25 igor kernel: Kernel log daemon terminating. > Aug 26 16:23:09 igor kernel: klogd 1.5.0#5, log source = /proc/kmsg started. <--- starting kernel boot, cpu, mmu, memory, ... are initialized, no time yet ---> > Aug 26 16:23:09 igor kernel: [ 0.000000] Initializing cgroup subsys cpu > Aug 26 16:23:09 igor kernel: [ 0.000000] Linux version 2.6.26-1-ixp4xx > (Debian 2.6.26-3) ([EMAIL PROTECTED]) (gcc version 4.1.3 20080623 > (prerelease) (Debian 4.1.2-23)) #1 Thu Aug 21 09:59:59 UTC 2008 > Aug 26 16:23:09 igor kernel: [ 0.000000] CPU: XScale-IXP42x Family > [690541f1] revision 1 (ARMv5TE), cr=0000397f ... > Aug 26 16:23:09 igor kernel: [ 0.000000] CPU0: I cache: 32768 bytes, > associativity 32, 32 byte lines, 32 sets > Aug 26 16:23:09 igor kernel: [ 0.000000] CPU0: D cache: 32768 bytes, > associativity 32, 32 byte lines, 32 sets <--- timer is initialized ---> > Aug 26 16:23:09 igor kernel: [42949372.960000] Built 1 zonelists in Zone > order, mobility grouping on. Total pages: 8128 > Aug 26 16:23:09 igor kernel: [42949372.960000] Kernel command line: > console=ttyS0,115200 rtc-x1205.probe=0,0x6f noirqdebug > Aug 26 16:23:09 igor kernel: [42949372.960000] Unknown boot option > `rtc-x1205.probe=0,0x6f': ignoring > > Thanks for any insight, > > --dkg > Best regards Marc see also : "CONFIG_PRINTK_TIME and generic sched_clock" on the linux arm kernel mailing list : http://thread.gmane.org/gmane.linux.ports.arm.kernel/43070 -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
