Messages in this thread |  | | | Date | Wed, 17 Mar 2010 09:59:36 -0400 | | From | Jason Baron <> | | Subject | Re: [PATCH RFC 00/11] lock monitor: Separate features related to lock |
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On Wed, Mar 17, 2010 at 10:52:30AM +0100, Ingo Molnar wrote: > * Frederic Weisbecker <fweisbec@gmail.com> wrote: > > > > You add chained indirect calls into all lock ops, that's got to hurt. > > > > Well, the idea was not bad at the first glance. It was separating lockdep > > and lock events codes. > > > > But indeed, the indirect calls plus the locking are not good for such a fast > > path. > > What would be nice to have is some sort of dynamic patching approach to enable > _both_ lockdep, lockstat and perf lock. >
right. this would allow distros to ship lockdep, lockstat in their default kernels as a runtime option.
> If TRACE_EVENT() tracepoints were patchable we could use them. (but they arent > right now) >
right. I'm going to re-post the jump labeling work again soon, which implicitly makes all TRACE_EVENT() tracepoints into dynamic patch points. The jump label approach can also be deployed independently of the tracepoints.
Also, any hints, suggestions on where to start with this type of project? I thought a lot of the lockdep overhead was tied up in the data structures? If its just a matter of identifying the dynamic patch points. I can convert them to jump label and run benchmarks, pretty easily.
thanks,
-Jason
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