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Message-ID: <alpine.DEB.1.10.0811181020350.15003@gandalf.stny.rr.com>
Date: Tue, 18 Nov 2008 10:22:07 -0500 (EST)
From: Steven Rostedt <rostedt@...dmis.org>
To: Ingo Molnar <mingo@...e.hu>
cc: Frederic Weisbecker <fweisbec@...il.com>,
Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] tracing/function-return-tracer: add the overrun
field
On Tue, 18 Nov 2008, Ingo Molnar wrote:
> > >
> > > that reminds me: ti->ret_stack[] should be moved to task->ret_stack[].
> > > That way we decouple its size from any kernel stack size limits.
> > > (thread-info resides at one end of the kernel stack, on x86)
> >
> > Yeah, I recommended that to Frederic to save space. But that can be
> > dangerous. Using task instead would be safer with the downside of
> > making the task struct even bigger.
>
> We almost never put new stuff into thread_info - we have the lockdep
> lock stack in the task structure too, for similar reasons.
Yeah, it was just a recommendation, and perhaps not a good one ;-)
Frederic, it is better if you move the array from the thread info to the
task struct. It will take up more memory but it is a hell of a lot safer.
The pro here definitely outways the con.
-- Steve
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