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SubjectRe: [PATCH 10/11] tracing/perf: Fix lock events recursions in the fast path
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On Sat, 2010-02-06 at 12:40 +0100, Frederic Weisbecker wrote:
> On Sat, Feb 06, 2010 at 12:24:02PM +0100, Peter Zijlstra wrote:
> > On Sat, 2010-02-06 at 12:12 +0100, Frederic Weisbecker wrote:
> >
> > > That said, I think this is good for a first step, but we can't continue
> > > to force the lock events -> lockdep dependency in the long term. We
> > > can't have a serious lock profiling if we are doomed to suffer the
> > > slowness due to lockdep checks at the same time.
> > >
> > > Sure we can continue to support having both, but I think we should also
> > > think about a solution to handle lock events without it in the future.
> > > That will require some minimal lockdep functionalities (keeping the
> > > lockdep map, and class hashes).
> >
> > You mean like building without CONFIG_PROVE_LOCKING, or boot with
> > lockdep.prove_locking=0, or use echo 0
> > > /sys/modules/lockdep/prove_locking ?
> >
> > That keeps the lock tracking but does away with all the dependency
> > analysis and was created for just such an use case as you are looking
> > at, namely lockstat.
>
>
> Looks pretty what I'm looking for. Except that it still continues
> to fill and keep track of the locks held by the current thread,
> namely the copies in curr->held_locks.

Which is exactly what you need for that lock hierarchy recording you
wanted :-)



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