Re: [PATCH 2/2] mm/page_ref: add tracepoint to track down page reference manipulation

From: Joonsoo Kim
Date: Wed Dec 09 2015 - 23:20:45 EST


On Wed, Dec 09, 2015 at 10:36:48PM -0500, Steven Rostedt wrote:
> On Thu, 10 Dec 2015 11:50:15 +0900
> Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> wrote:
>
> > Output of cpu 3, 7 are mixed and it's not easy to analyze it.
> >
> > I think that it'd be better not to sort stack trace. How do
> > you think about it? Could you fix it, please?
>
> It may not be that easy to fix because of the sorting algorithm. That
> would require looking going ahead one more event each time and then
> checking if its a stacktrace. I may look at it and see if I can come up
> with something that's not too invasive in the algorithms.

Okay.

> That said, for now you can use the --cpu option. I'm not sure I ever
> documented it as it was originally added for debugging, but I use it
> enough that it may be worth while to officially support it.
>
> trace-cmd report --cpu 3
>
> Will show you just cpu 3 and nothing else. Which is what I use a lot.

Thanks for the input. It works but it's not sufficient to me.
Page reference is manipulated by multiple cpus so it's better to
analyze unified output.

>
> But doing the stack trace thing may be something to fix as well. I'll
> see what I can do, but no guarantees.

Okay. Don't be hurry. :)
trace-cmd is excellent and works well for me as it is.

Thanks.
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