Messages in this thread | | | Date | Tue, 30 Dec 2008 16:37:52 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] tracing/kmemtrace: normalize the raw tracer event to the unified tracing API |
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* Frederic Weisbecker <fweisbec@gmail.com> wrote:
> On Tue, Dec 30, 2008 at 09:16:00AM +0100, Ingo Molnar wrote: > > > > * Pekka Enberg <penberg@cs.helsinki.fi> wrote: > > > > > Hi Frederic, > > > > > > On Mon, 2008-12-29 at 23:09 +0100, Frederic Weisbecker wrote: > > > > Pekka, note that I would be pleased to add statistical tracing on > > > > this tracer, but I would need a hashtable, or an array, or a list, or whatever > > > > iterable to insert the data into the stat tracing api. > > > > > > > > But I don't know your projects about this... whether you wanted to use a section > > > > or something else... > > > > > > It really depends on what we're tracing. If we're interested in just the > > > allocation hotspots, a section will do just fine. However, if we're > > > tracing memory footprint, we need to take into store the object pointer > > > returned from kmalloc() and kmem_cache_alloc() so we can update > > > call-site statistics properly upon kfree(). > > > > > > So I suppose we need both, a section for per call-site statistics and a > > > hash table for the object -> call-site mapping. > > > > 1) > > > > i think the call_site based tracking should be a built-in capability - the > > branch tracer needs that too for example. That would also make it very > > simple on the usage place: you wouldnt have to worry about sections in > > slub.c/etc. > > > I think that too. Can we use sections here? The traced functions are not > directly kmalloc/kmem_cache_alloc and to use a section which contains > the per site allocation requests, such a thing is required (we can't > build a section with per site allocations requests by using intermediate > level allocation function I fear...).
i think initially this should be a fixed-size allocation array + hash as well. (like lockdep uses) The number of allocation sites is even the most extreme case at most a few thousand - and is typically at most a couple of hundred.
Ingo
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