gngjeg@gmail.com wrote: > I would like to apoligize if this question is being posted to the > wrong group. > > I would like to know what is the most bullet-proof way to determine > what clock source is the Linux kernel using. Normally, I dod this > making use of "dmesg" as the text below shows. > > [joseg@dev03 proc]$ dmesg | grep time.c > time.c: Using 3.579545 MHz PM timer. > time.c: Detected 2599.956 MHz processor. > time.c: Using PM based timekeeping. > [joseg@dev03 proc]$ > > [joseg@prod03 ~]$ dmesg | grep time.c > time.c: Using 1.193182 MHz PIT timer. > time.c: Detected 2599.994 MHz processor. > time.c: Using PIT/TSC based timekeeping. > [joseg@prod03 ~]$ > > The issue with relying on "dmesg" is that eventually, the message > buffer might get over written on very busy servers or servers that > have been up for a very long time. > > There is another way that I can use to check for the source, and that > is by looking at "/proc/cmdline" as the text shows below. > > [joseg@prod03 ~]$ cat /proc/cmdline > ro root=LABEL=/ rhgb quiet nohpet nopmtimer console=tty0 > [joseg@prod03 ~] > > However, not all systems will have the clock source clearly defined on > the kernel boot options under your /boot/grub/menu.lst file. The text > below shows a systems which do not specify which clock source the > kernel is supposed to pick. > > [joseg@dev03 ~]$ cat /proc/cmdline > ro root=LABEL=/ rhgb quiet console=tty0 > [joseg@dev03 ~]$ > > There is some heuristics built into the kernel (time.c) which will > pick one of the available time or clock sources based on what it is > available to the system at boot time and what is enabled/disabled in > the BIOS. > > So, is there a way that will help someone that might not have access > to boot time messages or access to a boot.log to make an accurate > determination as to which clock source a particular system is running? > > Thanks in advance. > Using kernel 2.6.23: ls /sys/devices/system/clocksource/clocksource0/ available_clocksource current_clocksource cat /sys/devices/system/clocksource/clocksource0/* acpi_pm pit jiffies tsc acpi_pm Jerry