Messages in this thread | | | Date | Tue, 18 Nov 2008 16:50:45 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 3/3] tracing/function-return-tracer: add the overrun field |
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* Steven Rostedt <rostedt@goodmis.org> wrote:
> > 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.
if the memory footprint starts mattering we could turn this into a single pointer to an array - and add/remove these arrays (from all tasks currently running) as the tracer is turned on/off.
Ingo
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