Re: [PATCHv2 2/2] tracing,mm - add kernel pagefault tracepoint for x86 & x86_64

Steven Rostedt
2010-11-15T15:04:21Z

On Mon, 2010-11-15 at 15:54 +0100, Frederic Weisbecker wrote:
> On Mon, Nov 15, 2010 at 03:06:33PM +0100, Andi Kleen wrote:

> > For tracing the whole page fault me think it's better to have
> > a generalized exception tracer with a filter on page fault.
>
>
> You're right. A tracepoint in handle_mm_fault() would be perhaps
> better. It should catch most tracepoints the users are interested
> in. On the other hand we may miss part of the page fault
> latency, like the mmap_sem contention. This can be measured using
> lock events though.
>
> But I'm probably missing other important things.

I would have the general exception handler as a tracepoint that would
have a "stable tracepoint" hook to it. That is, when enabling it as a
infield debugging tracepoint, we would get the "raw tracepoint", but the
stable tracepoint would massage it into different general types of
exceptions, and the code there would do the filtering.

-- Steve