Re: 2.6.15-rt4 failure with LATENCY_TRACE on x86_64

[Clark Williams]

On Thu, 2006-01-12 at 22:18 -0500, Steven Rostedt wrote:
> 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.
> 
Hmm, I didn't realize that (I'm running on a uni-processor system). I
just pulled your rt4-sr2 patch and will apply/rebuild/test. 

> 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?

No, I thought that was strictly an SMP issue. I'll try it as well.

Thanks,
Clark

-- 
Clark Williams <williams@xxxxxxxxxx>

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