Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace() methods

[Chris Metcalf]

On 3/17/2016 3:36 PM, Peter Zijlstra wrote:
> On Wed, Mar 16, 2016 at 01:02:10PM -0400, Chris Metcalf wrote:
> > Currently you can only request a backtrace of either all cpus, or
> > all cpus but yourself.  It can also be helpful to request a remote
> > backtrace of a single cpu, and since we want that, the logical
> > extension is to support a cpumask as the underlying primitive.
> >
> > This change modifies the existing lib/nmi_backtrace.c code to take
> > a cpumask as its basic primitive, and modifies the linux/nmi.h code
> > to use either the old "all/all_but_self" arch methods, or the new
> > "cpumask" method, depending on which is available.
> >
> > The existing clients of nmi_backtrace (arm and x86) are converted
> > to using the new cpumask approach in this change.
> So the past days I've been staring at RCU stall warns, and they can use
> a little of this. Their remote stack unwinds are less than useful.

Were you suggesting this as an improvement for a possible v3, or just a
kind of implicit ack of the patch series?  Thanks!

--
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com