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Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited private command

From	Peter Zijlstra <peterz@infradead.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited private command
Date	2017-09-29 13:50 +0200
Message-ID	<uv1XP-5Dl-1@gated-at.bofh.it> (permalink)
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On Fri, Sep 29, 2017 at 09:38:53PM +1000, Nicholas Piggin wrote:

> Not really. There is some ability to hold onto a line for a time, but
> there is no way to starve them, let alone starve hundreds of other
> CPUs. They will request the cacheline exclusive and eventually get it.

OK, hardware fairness there is nice.

> I would really prefer to go this way on powerpc first. We could add the
> the registration APIs as basically no-ops, but which would allow the
> locking approach to be changed if we find it causes issues. I'll try to
> find some time and a big system when I can.

Fair enough I suppose.

> > A semi related issue; I suppose we can do a arch upcall to flush_tlb_mm
> > and reset the mm_cpumask when we change cpuset groups.
> 
> For powerpc we have been looking at how mm_cpumask can be improved.
> It has real drawbacks even when you don't consider this new syscall.

What else do you use mm_cpumask for?

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[PATCH v4 for 4.14 1/3] membarrier: Provide register expedited private command Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2017-09-26 20:00 +0200
  Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited  private command Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2017-09-26 22:50 +0200
    Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited  private command Nicholas Piggin <npiggin@gmail.com> - 2017-09-27 15:10 +0200
      Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited  private command Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2017-09-28 15:40 +0200
        Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited  private command Nicholas Piggin <npiggin@gmail.com> - 2017-09-28 17:10 +0200
          Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited  private command Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2017-09-28 17:30 +0200
            Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited  private command Nicholas Piggin <npiggin@gmail.com> - 2017-09-28 18:20 +0200
              Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited  private command Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2017-09-28 20:30 +0200
          Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited  private command Peter Zijlstra <peterz@infradead.org> - 2017-09-28 18:00 +0200
            Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited  private command Nicholas Piggin <npiggin@gmail.com> - 2017-09-28 18:30 +0200
              Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited  private command Peter Zijlstra <peterz@infradead.org> - 2017-09-29 12:40 +0200
                Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited  private command Nicholas Piggin <npiggin@gmail.com> - 2017-09-29 13:40 +0200
                Re: [PATCH v4 for 4.14 1/3] membarrier: Provide register expedited  private command Peter Zijlstra <peterz@infradead.org> - 2017-09-29 13:50 +0200

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