Messages in this thread |  | | | Subject | Re: 2.6.15-rt4 failure with LATENCY_TRACE on x86_64 | | From | Steven Rostedt <> | | Date | Thu, 12 Jan 2006 22:18:00 -0500 |
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On Thu, 2006-01-12 at 16:07 -0600, Clark Williams wrote: > Ingo/Steve, > > Did I miss a "Don't turn on latency tracing for x86_64" message > somewhere? > > I'm seeing a failure on my Athlon64 3000+ where, when I turn on > CONFIG_LATENCY_TRACE, the init program segfaults. Doesn't happen with a > statically linked shell like sash (e.g. init=/sbin/sash boots ok), but > if /sbin/init or /bin/sh is used, the init program segfaults. Presumably > any dynamically linked program will fail. > > Attached is console output for a boot failure (segfault messages > truncated after four lines, since they're all the same) as well as the > config files for both working and failing kernels. > > I'm not sure where to start looking on this one. Barring any advise, I'm > going to look for occurrences of CONFIG_LATENCY_TRACE, especially in > proximity to exec.
OK, I'm actually sending you this email on a x86_64 running 2.6.15-rt4-sr2, with latency tracing on. But unfortunately, I have a AMD X2 that each core has it's own tsc counter that is not in sync, and since the latency tracer uses tsc, I get garbage. But beware, the tsc does slow down when the cpu idles, so it gives bad results even for non x2 systems.
I finally was able to boot this with using the PM timer, but the beginning of my dmesg is still filled with:
read_tsc: ACK! TSC went backward! Unsynced TSCs?
Have you tried booting with idle=poll? I wonder if that would help?
-- Steve
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