Re: How to reset the timestamp value in Suse 10 system

song_winter@xxxxxxxxxxx schrieb:


The Linux kernel must be configured with the CONFIG_X86_TSC option
enabled in order to use the TSC. Make sure this option is enabled in
your kernel.

First, check the output of

$ gunzip -c /proc/config.gz | grep CONFIG_X86_TSC

Does it say "...=y"? If no, you have to recompile your kernel. Install the
kernel sources, run

$ su
# cd /usr/src/linux
# gunzip -c /proc/config.gz >.config
# make menuconfig

Enable "High Resolution Timer Support" inside the "Processor Type and
Features"

# make
# make install
# make modules_install

Besides, you should check a kernel building howto like this:

http://www.digitalhermit.com/linux/Kernel-Build-HOWTO.html

to get an overview of what you are trying to do.




If yes, you already have TSC support in your kernel and maybe (unlikely) the
section below applies:

In addition, some Linux distributions may have bugs in their versions
of the kernel that cause packets not to be given high-resolution time
stamps even if the TSC is enabled. See, for example, bug 61111 for Red
Hat Linux 7.2. If your distribution has a bug such as this, you may
have to run a standard kernel from kernel.org in order to get high-
resolution time stamps.

In that case, you have to use the vanilla kernel sources instead of the
(broken) kernel source package of your distribution.

Kind regards

Jan
.

Relevant Pages

  • Re: [PATCH] Skip tsc synchronization checks if CONSTANT_TSC bit is set.
    ... Hypervisor couldn't as well be fixed. ... However, when running the kernel on virtual cpus, as compared to running on a physical cpus, the timing characteristics are different -- virtual cpus have to time share physical cpus with each other. ... The fast-path TSC calibration code makes assumptions about being able to sample various counters in sequence in a set amount of time that are not true when running virtualized. ...
    (Linux-Kernel)
  • Re: Improving the kernel/i386 timecounter performance (GSoC proposal)
    ... functions that can be called by user applications, ... chosen by the kernel at boot time depending on processor capabilities. ... TSC may be ti=king at this CPU, and export in the same page. ...
    (freebsd-current)
  • Re: Improving the kernel/i386 timecounter performance (GSoC proposal)
    ... one global for gettimeofday and one per-process for static data like getpid/getgid. ... a page in the kernel mapped read-only to all the user pr=cesses. ... TSC may be ti=king at this CPU, and export in the same page. ...
    (freebsd-current)
  • Re: Improving the kernel/i386 timecounter performance (GSoC proposal)
    ... one global for gettimeofday and one per-process for static data like getpid/getgid. ... a page in the kernel mapped read-only to all the user pr=cesses. ... TSC may be ti=king at this CPU, and export in the same page. ...
    (freebsd-hackers)
  • TSC cannot be used as a timesource -> SOLVED
    ... DMA, I always had it off for that disk; ... since its release, kernel 2.6.0 ... TSC cannot be used as a timesource. ... the system clock was running behind ca. 45 minutes! ...
    (Linux-Kernel)