Re: [time-nuts] Linux timekeeping / jiffy source

2010-12-03 Thread bownes
Thanks for the correction/education! On Dec 3, 2010, at 2:17 AM, Christian Vogel wrote: > Hi bownes, > >> Unfortunately, there is no way to restart the kernel without going through a >> BIOS re initialization. > > actually, there is. It's called "kexec". > > See, for example http://www.ibm

Re: [time-nuts] Linux timekeeping / jiffy source

2010-12-03 Thread Mike S
On Dec 2, 2010, at 10:17 PM, mi...@flatsurface.com (Mike S) wrote: is it possible to restart the Linux kernel without a full reboot (avoiding BIOS initialization) At 02:17 AM 12/3/2010, Christian Vogel wrote... It's called "kexec". Thanks. I'll try it in a bit. At 02:22 AM 12/3/2010, Hal M

Re: [time-nuts] Linux timekeeping / jiffy source

2010-12-02 Thread Kasper Pedersen
On 12/03/2010 04:17 AM, Mike S wrote: > Anyone familiar with Linux kernel timekeeping? > On boot, the kernel picks a clocksource. If the cpu is recent, and it is not forced, the tsc (cpu) counter gets chosen. The tsc increment rate is initially unknown, and is measured against pit (8253/8254), an

Re: [time-nuts] Linux timekeeping / jiffy source

2010-12-02 Thread Hal Murray
> Sync'ing to a local GPS locked NTP server, I see up to an 80 ppm spread > between reboots, which I've documented at http://www.flatsurface.com/ > AMD_SB850/index.html . I'm running kernel 2.6.32 (Debian squeeze). I'm not familiar with AMD, but there is a bug in the Intel world that matches y

Re: [time-nuts] Linux timekeeping / jiffy source

2010-12-02 Thread Christian Vogel
Hi bownes, Unfortunately, there is no way to restart the kernel without going through a BIOS re initialization. actually, there is. It's called "kexec". See, for example http://www.ibm.com/developerworks/linux/library/l-kexec.html . Greetings from Germany, Chris

Re: [time-nuts] Linux timekeeping / jiffy source

2010-12-02 Thread Robert Darlington
Are you running ntp, and if so, did you kill the old drift file? On Dec 2, 2010 8:18 PM, "Mike S" wrote: Anyone familiar with Linux kernel timekeeping? I've recently upgraded a server to an AMD 890FX/SB850 based motherboard. After doing so, I observed a large (in time-nut terms) inconsistency i

Re: [time-nuts] Linux timekeeping / jiffy source

2010-12-02 Thread bownes
Unfortunately, there is no way to restart the kernel without going through a BIOS re initialization. Changing the run level restarts the init process but does not reload the kernel. On Dec 2, 2010, at 10:17 PM, mi...@flatsurface.com (Mike S) wrote: > Anyone familiar with Linux kernel timek

[time-nuts] Linux timekeeping / jiffy source

2010-12-02 Thread Mike S
Anyone familiar with Linux kernel timekeeping? I've recently upgraded a server to an AMD 890FX/SB850 based motherboard. After doing so, I observed a large (in time-nut terms) inconsistency in system timing, as seen in the rate of the system's Time Of Day clock. Sync'ing to a local GPS locked