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Groups > linux.kernel > #1250394

Re: Q: schedule() and implied barriers on arm64

From Ingo Molnar <mingo@kernel.org>
Newsgroups linux.kernel
Subject Re: Q: schedule() and implied barriers on arm64
Date 2015-10-19 09:10 +0200
Message-ID <qlcJX-5we-5@gated-at.bofh.it> (permalink)
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* Peter Zijlstra <peterz@infradead.org> wrote:

> In any case, its all moot now, since Paul no longer requires schedule() to imply 
> a full barrier.
>
> [...]

Nevertheless from a least-surprise POV it might be worth guaranteeing it, because 
I bet there's tons of code that assumes that schedule() is a heavy operation and 
it's such an easy mistake to make. Since we are so close to having that guarantee, 
we might as well codify it?

Just like system calls are assumed to be barriers in general - and system calls 
are more lightweight than schedule() ...

Thanks,

	Ingo
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Thread

Q: schedule() and implied barriers on arm64 Peter Zijlstra <peterz@infradead.org> - 2015-10-16 17:20 +0200
  Re: Q: schedule() and implied barriers on arm64 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-16 18:10 +0200
    Re: Q: schedule() and implied barriers on arm64 Peter Zijlstra <peterz@infradead.org> - 2015-10-16 18:20 +0200
      Re: Q: schedule() and implied barriers on arm64 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-16 18:40 +0200
        Re: Q: schedule() and implied barriers on arm64 Peter Zijlstra <peterz@infradead.org> - 2015-10-16 18:40 +0200
      Re: Q: schedule() and implied barriers on arm64 Catalin Marinas <catalin.marinas@arm.com> - 2015-10-16 19:00 +0200
        Re: Q: schedule() and implied barriers on arm64 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-16 19:30 +0200
          Re: Q: schedule() and implied barriers on arm64 Peter Zijlstra <peterz@infradead.org> - 2015-10-16 21:10 +0200
            Re: Q: schedule() and implied barriers on arm64 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-16 21:30 +0200
          Re: Q: schedule() and implied barriers on arm64 Catalin Marinas <catalin.marinas@arm.com> - 2015-10-19 17:20 +0200
        Re: Q: schedule() and implied barriers on arm64 Peter Zijlstra <peterz@infradead.org> - 2015-10-16 21:10 +0200
          Re: Q: schedule() and implied barriers on arm64 Ingo Molnar <mingo@kernel.org> - 2015-10-19 09:10 +0200
            Re: Q: schedule() and implied barriers on arm64 Peter Zijlstra <peterz@infradead.org> - 2015-10-19 11:10 +0200
            Re: Q: schedule() and implied barriers on arm64 Catalin Marinas <catalin.marinas@arm.com> - 2015-10-19 17:30 +0200
              Re: Q: schedule() and implied barriers on arm64 Peter Zijlstra <peterz@infradead.org> - 2015-10-19 18:30 +0200
                Re: Q: schedule() and implied barriers on arm64 Ingo Molnar <mingo@kernel.org> - 2015-10-20 10:40 +0200
                Re: Q: schedule() and implied barriers on arm64 Will Deacon <will.deacon@arm.com> - 2015-10-27 17:30 +0100
                Re: Q: schedule() and implied barriers on arm64 Peter Zijlstra <peterz@infradead.org> - 2015-10-28 01:20 +0100
                Re: Q: schedule() and implied barriers on arm64 Will Deacon <will.deacon@arm.com> - 2015-10-28 11:50 +0100
    Re: Q: schedule() and implied barriers on arm64 Catalin Marinas <catalin.marinas@arm.com> - 2015-10-16 19:20 +0200

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