Re: [PATCH 3/3] tracing/function-return-tracer: add the overrunfield

From: Ingo Molnar
Date: Tue Nov 18 2008 - 09:52:19 EST



* Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

>
> On Tue, 18 Nov 2008, Ingo Molnar wrote:
> > >
> > > Ok I will try with 50. If there are still a lot and often missing
> > > traces with this depth, perhaps should we consider a hybrid solution
> > > between ret stack and trampolines? We could use the normal ret stack
> > > on struct info for most common cases and the trampoline when we are
> > > exceeding the depth....
> >
> > dunno, trampolines make me feel uneasy.
> >
> > Could you set it to some really large value (200) and add a "max
> > depth seen" variable perhaps, and see the maximum depth?
>
> Don't run that on a box you care about ;-) But hopefully the stacks
> will not collide. This should also depend on IRQSTACKS.

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)

Ingo
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