On 07/18/2013 06:06 PM, Mahshid Sedghi wrote:
I was wondering if anybody has experienced this prompt when running in
x86 FS mode:
Clocksource tsc unstable (delta = <some big number> ns)
Apparently this message is shown when the system has multiple
available clock sources. When running gem5 in the mentioned mode, this
message is occasionally shown and usually stops the execution from
proceeding. Is there a solution to fix the problem?
I haven't seen it in any of the normal CPU models, but I have similar
issues when using KVM (hardware virtualization) in gem5. Depending on
what causes this problem and your kernel version you could try one of
the following:
* Switch to a different clocksource. For example, append
"clocksource=jiffies" to the kernel command line (see boot_osflags in
FSConfig.py if you are using the example scripts).
* Force the kernel to treat the TSC as reliable (append "tsc=reliable")
* Disable the TSC (append "notsc"). The kernel should automatically
choose a different clocksource if you append this option.
Also, your kernel might be slightly confused if you have changed the
clock frequency of your CPU without removing/updating the "lpj=x" option
as this forces the kernel to use a timing calibrated for a different CPU.
Yet another possibility is that you have an old version of gem5 that has
a bug that causes the TSC to jump (sometimes backwards) when switching
CPUs. That was fixed by HG changeset e039a48eeb99 (git: 0b4a8b4086).
//Andreas
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