Re: [RFC] [PATCH 0/2] x86: make jump labels use int3-based breakpointinstead of stop_machine()

From: Jiri Kosina
Date: Thu Jul 11 2013 - 15:23:25 EST


On Thu, 11 Jul 2013, Steven Rostedt wrote:

> On Thu, 2013-07-11 at 02:04 +0200, Jiri Kosina wrote:
>
> > I even have preliminary (completely untested) patch, but would like to
> > have this merged/acked in the first round before proceeding with porting
> > ftrace to the new interface.
> >
> > > Also, I wonder if its worth batching up updates. For example, right now
> > > we simply update each call-site one at a time even if its associated
> > > with the same control variable.
> >
> > That does seem to make sense indeed, but it's not really closely tied to
> > this patchset, is it?
>
> If you want to have ftrace use this interface, then we need to support
> batch processing. And you will need to do it with an iterator as well.
> We can not allocate 30,000 locations to run this on. Ftrace has its own
> table, and uses the ftrace iterator to traverse it.
>
> Thus you would need to do something like:

Yup, I have been looking at the ftrace implementation and came to this
conclusion; thanks for confirmation.
That's exactly why I wanted to postpone converting ftrace before agreement
on text_poke_bp() is reached and jump labels are converted.

Thanks,

--
Jiri Kosina
SUSE Labs
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