Re: [patch] Latency Tracer, voluntary-preempt-2.6.8-rc4-O6

[Ingo Molnar]

* Andi Kleen <ak@xxxxxx> wrote:

> >> Interesting results.  One of the problems is kallsyms_lookup,
> >> triggered by the printks:
> >
> > yeah - kallsyms_lookup does a linear search over thousands of symbols. 
> > Especially since /proc/latency_trace uses it too it would be worthwile
> > to implement some sort of binary searching.
> 
> Or just stick some cond_sched()s in there. It was designed to be slow,
> but there are no locking issues.

the speedup would be important: even on a 2GHz box reading 10,000 trace
entries takes a couple of seconds.

[ the /proc/latency_trace read()ing itself is fully preemptible, i'd be
  ashamed if it werent ;) ]

	Ingo
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