From mboxrd@z Thu Jan  1 00:00:00 1970
From: Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: linux-next: add utrace tree
Date: Wed, 27 Jan 2010 17:01:06 +0100
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To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>, Tom Tromey <tromey@redhat.com>, Kyle Moffett <kyle@moffetthome.net>, "Frank Ch. Eigler" <fche@redhat.com>, Oleg Nesterov <oleg@redhat.com>, Andrew Morton <akpm@linux-foundation.org>, Stephen Rothwell <sfr@canb.auug.org.au>, LKML <linux-kernel@vger.kernel.org>, Steven Rostedt <rostedt@goodmis.org>, Arnaldo Carvalho de Melo <acme@redhat.com>, linux-next@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>, utrace-devel@redhat.com, Thomas Gleixner <tglx@linutronix.de>, JimKeniston <jkenisto@us.ibm.com>

On Wed, Jan 27, 2010 at 03:04:58AM -0800, Linus Torvalds wrote:
> 
> 
> On Wed, 27 Jan 2010, Peter Zijlstra wrote:
> > 
> > Right, so there's two aspects:
> > 
> >  1) concurrency when inserting the probe
> 
> That's the one I worried about. Stopping all threads will fix it, 
> obviously at a disastrous performance cost, but what do I care? As noted, 
> there are ways to do it safely with TLB switching, so it's fixable.


That said, inserting a probe is supposed to be a pretty rare
operation, stopping all threads in a process shouldn't be
painful for this aspect.