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Date:   Mon, 5 Sep 2022 18:16:50 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Kent Overstreet <kent.overstreet@linux.dev>
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Subject: Re: [RFC PATCH 00/30] Code tagging framework and applications
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On Mon, 5 Sep 2022 16:42:29 -0400
Kent Overstreet <kent.overstreet@linux.dev> wrote:

> > Haven't tried that yet but will do. Thanks for the reference code!  
> 
> Is it really worth the effort of benchmarking tracing API overhead here?
> 
> The main cost of a tracing based approach is going to to be the data structure
> for remembering outstanding allocations so that free events can be matched to
> the appropriate callsite. Regardless of whether it's done with BFP or by
> attaching to the tracepoints directly, that's going to be the main overhead.

The point I was making here is that you do not need your own hooking
mechanism. You can get the information directly by attaching to the
tracepoint.

> > static void my_callback(void *data, unsigned long call_site,
> >                         const void *ptr, struct kmem_cache *s,
> >                         size_t bytes_req, size_t bytes_alloc,
> >                         gfp_t gfp_flags)
> > {
> >         struct my_data_struct *my_data = data;
> >
> >         { do whatever }
> > }

The "do whatever" is anything you want to do.

Or is the data structure you create with this approach going to be too much
overhead? How hard is it for a hash or binary search lookup?


-- Steve