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

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace() methods
Date 2016-03-17 23:40 +0100
Message-ID <rdOKf-54a-29@gated-at.bofh.it> (permalink)
References <rdLW2-35m-9@gated-at.bofh.it> <rdLW2-35m-11@gated-at.bofh.it> <rdLW2-35m-7@gated-at.bofh.it> <rdOKe-54a-13@gated-at.bofh.it>
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On Thu, Mar 17, 2016 at 06:31:44PM -0400, Chris Metcalf wrote:
> 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!

A suggestion more like. I've not actually looked at the 4th patch.

I'll try and fold the patches into the runs I do tomorrow, I'm sure to
trigger lots of fail. Maybe I'll even do that RCU patch.

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Thread

Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace()  methods Peter Zijlstra <peterz@infradead.org> - 2016-03-17 20:40 +0100
  Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace()  methods Chris Metcalf <cmetcalf@mellanox.com> - 2016-03-17 23:40 +0100
    Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace()  methods Peter Zijlstra <peterz@infradead.org> - 2016-03-17 23:40 +0100
      Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace()  methods Peter Zijlstra <peterz@infradead.org> - 2016-03-18 00:20 +0100
  Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace()  methods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-03-18 00:00 +0100
    Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace()  methods Peter Zijlstra <peterz@infradead.org> - 2016-03-18 00:10 +0100
    Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace()  methods Peter Zijlstra <peterz@infradead.org> - 2016-03-18 00:20 +0100
      Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace()  methods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-03-18 01:40 +0100
    Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace()  methods Chris Metcalf <cmetcalf@mellanox.com> - 2016-03-18 01:20 +0100
      Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace()  methods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-03-18 01:50 +0100
        Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace()  methods Daniel Thompson <daniel.thompson@linaro.org> - 2016-03-18 10:50 +0100
          Re: [PATCH v2 1/4] nmi_backtrace: add more trigger_*_cpu_backtrace()  methods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-03-19 01:00 +0100

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