* Jörn Engel <joern@logfs.org> wrote:

quoted text
> I do.  Went through 10odd runs and annotated the function right below 
> mcount each time.  Seems to work now.
> 
> Trouble is that it doesn't solve my real problem at hand.  Something 
> is causing significant delays when writing to logfs.  Core logfs code 
> is not running, but may cause whatever other code is running and 
> burning up all the cpu time.  Wasting 100ms of "qemu-time" to write a 
> single page happens fairly frequently.
> 
> With the latency tracer the problem appears to have become worse.  Now 
> the loftlockup code triggers quite frequently.  Which makes a bit of 
> sense, as the problem is a busy CPU, rather than an idle one.

well what does the trace say, where do the delays come from? To get a 
quick overview you can make tracing lighter weight by doing:

 echo 0 > /proc/sys/kernel/mcount_enabled
 echo 1 > /proc/sys/kernel/trace_syscalls

(this turns the latency tracer into a "global strace" kind of tracer)

	Ingo
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