Messages in this thread | | | Date | Sat, 3 Jan 2009 00:38:50 +0200 | From | Eduard - Gabriel Munteanu <> | Subject | Re: [PATCH 2/2] kmemtrace: Use tracepoints instead of markers. |
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On Fri, Jan 02, 2009 at 04:48:05PM -0500, Mathieu Desnoyers wrote: > Yes, we could (and maybe should) use __always_inline there. Hrm, which > which tree to you work ? You probably mean DECLARE_TRACE() rather than > DEFINE_TRACE() ? > > I just went over your patch again. it uses the old DEFINE_TRACE() API. > You should get the latest tracepoints which have DECLARE_TRACE() (for > trace/kmemtrace.h) and then a DEFINE_TRACE() in a .c. Ah I see, you > work on 2.6.28. You should work on top of -tip, which has this new API. > Using the tracepoints present in 2.6.28 will not let you do only a > single definition of the tracepoint structure and it will lead to waste > of kernel memory by defining multiple instances of tracepoint structures > (one for each trace_*() use, so one per kmalloc()). The > Documentation/tracepoints.txt file is updated accordingly. >
I'm supposed to merge it through Ingo's tip tree. If we're talking about the same tree, I'll do as you suggested.
> > But it is quite pointless. Sometimes we need _RET_IP_, sometimes > > _THIS_IP_ and sometimes a parameter we've been passed. That's because we > > want the IP of the caller, so it depends on whether this slab function > > is __always_inline, non-inlined or deeply nested within other functions > > (which can be as well __always_inline or non-inlined). > > > > Hrm ? In the case we just want > > trace_kmalloc(_THIS_IP, ......); > > If we have __always_inline for the trace_*() declaration, isn't it the > same to just do this in the probe ? > > void probe_kmalloc(......) > { > ... _RET_IP_ ...; > > } > > This would remove a parameter from the stack created from the > instrumentation site, which is always good.
No, it's not always possible. Not all allocator functions (not even those of the same kind, as in alloc/free) make up an __always_inline chain. For example, there is one or a few instances where we pass a value other than _RET_IP_ or _THIS_IP_ to probes. It's quite hard to untangle things without making extensive modifications.
> Mathieu > > > > > Eduard > > > > -- > Mathieu Desnoyers > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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