Re: [RFC] gcc feature request: Moving blocks into sections

[H. Peter Anvin]

On 08/05/2013 10:55 AM, Steven Rostedt wrote:
> 
> Well, as tracepoints are being added quite a bit in Linux, my concern is
> with the inlined functions that they bring. With jump labels they are
> disabled in a very unlikely way (the static_key_false() is a nop to skip
> the code, and is dynamically enabled to a jump).
> 

Have you considered using traps for tracepoints?  A trapping instruction
can be as small as a single byte.  The downside, of course, is that it
is extremely suppressed -- the trap is always expensive -- and you then
have to do a lookup to find the target based on the originating IP.

	-hpa


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