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Subject: Re: [PATCH v2 7/11] Uprobes Implementation
From: Peter Zijlstra <peterz@infradead.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>, Ingo Molnar <mingo@elte.hu>,
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Date: Tue, 11 May 2010 22:32:18 +0200
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On Tue, 2010-04-20 at 17:30 +0200, Oleg Nesterov wrote:
> > >     - I don't really understand why ->handler_in_interrupt is really
> > >       useful, but never mind.
> >
> > There is a small overhead when running the handlers in task context.
> 
> Sure, but
> 
> > overhead of task over interrupt =  (1.016851 - .907400) = .109451 usec
> > % additional overhead = (.109451/.907400) * 100 = 12.062%
> 
> this overhead looks very minor. To me, it is better to simplify the
> code, at least in the first version.
> 
> That said, this is up to you, I am not asking you to remove this
> optimization. Just imho. 

Right so what I've suggested several times it to simply call the same
handler in both contexts. If it returns -EFAULT, set TIF_UPROBE or
whatever and try again from task context.