Re: [PATCH v7 05/11] task_isolation: add debug boot flag

Andy Lutomirski
2015-09-28T21:00:09Z

On Mon, Sep 28, 2015 at 11:17 AM, Chris Metcalf <cmetcalf@ezchip.com> wrote:
> The new "task_isolation_debug" flag simplifies debugging
> of TASK_ISOLATION kernels when processes are running in
> PR_TASK_ISOLATION_ENABLE mode. Such processes should get no
> interrupts from the kernel, and if they do, when this boot flag is
> specified a kernel stack dump on the console is generated.
>
> It's possible to use ftrace to simply detect whether a task_isolation
> core has unexpectedly entered the kernel. But what this boot flag
> does is allow the kernel to provide better diagnostics, e.g. by
> reporting in the IPI-generating code what remote core and context
> is preparing to deliver an interrupt to a task_isolation core.
>
> It may be worth considering other ways to generate useful debugging
> output rather than console spew, but for now that is simple and direct.

This may be addressed elsewhere, but is there anything that alerts the
task or the admin if it's PR_TASK_ISOLATION_ENABLE and *not* on a
nohz_full core?

--Andy