Subject: Re: [PATCH] tracing/kmemtrace: normalize the raw tracer event to
	the unified tracing API
From: Pekka Enberg <penberg@cs.helsinki.fi>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Steven Rostedt <rostedt@goodmis.org>,
       Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>, mingo@elte.hu
In-Reply-To: <20081229220937.GC5829@nowhere>
References: <4959443f.09a1660a.44f3.2686@mx.google.com>
	 <20081229220937.GC5829@nowhere>
Date: Tue, 30 Dec 2008 09:49:24 +0200
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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.

		Pekka

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