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Groups > linux.kernel > #1243250
| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation |
| Date | 2015-10-09 13:10 +0200 |
| Message-ID | <qhDIJ-i3-7@gated-at.bofh.it> (permalink) |
| References | (4 earlier) <qhax4-en-5@gated-at.bofh.it> <qhhoS-1PL-3@gated-at.bofh.it> <qhreB-7rq-87@gated-at.bofh.it> <qhBnz-5g1-1@gated-at.bofh.it> <qhCtk-6Ne-25@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, Oct 09, 2015 at 10:40:39AM +0100, Will Deacon wrote:
> Stepping back a second, I believe that there are three cases:
>
>
> RELEASE X -> ACQUIRE Y (same CPU)
> * Needs a barrier on TSO architectures for full ordering
+PPC
> UNLOCK X -> LOCK Y (same CPU)
> * Needs a barrier on PPC for full ordering
> RELEASE X -> ACQUIRE X (different CPUs)
* Fully ordered everywhere...
* ... but needs a barrier on TSO + PPC to become a full barrier
> UNLOCK X -> ACQUIRE X (different CPUs)
s/ACQUIRE/LOCK/ ?
> * Fully ordered everywhere...
> * ... but needs a barrier on PPC to become a full barrier
If you really meant ACQUIRE, then x86 also needs a barrier in order to
upgrade, seeing how our unlock is equivalent to smp_store_release(). Our
LOCK otoh is far heavier than smp_load_acquire() and would result in
different rules.
And I'm not sure the "(different CPUs)" bit makes sense, as the same is
true if they're on the same CPU.
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[PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Will Deacon <will.deacon@arm.com> - 2015-10-07 13:10 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Peter Zijlstra <peterz@infradead.org> - 2015-10-07 13:20 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Will Deacon <will.deacon@arm.com> - 2015-10-07 15:30 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Peter Zijlstra <peterz@infradead.org> - 2015-10-07 17:00 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-07 17:30 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Michael Ellerman <mpe@ellerman.id.au> - 2015-10-08 06:00 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Peter Zijlstra <peterz@infradead.org> - 2015-10-08 13:20 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Will Deacon <will.deacon@arm.com> - 2015-10-08 15:00 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-09 00:20 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Will Deacon <will.deacon@arm.com> - 2015-10-09 12:00 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Peter Zijlstra <peterz@infradead.org> - 2015-10-09 13:30 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-09 19:50 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-09 19:50 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Will Deacon <will.deacon@arm.com> - 2015-10-09 20:40 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-13 01:40 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-08 23:50 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Peter Zijlstra <peterz@infradead.org> - 2015-10-09 09:30 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Peter Zijlstra <peterz@infradead.org> - 2015-10-09 10:40 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Will Deacon <will.deacon@arm.com> - 2015-10-09 11:50 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Peter Zijlstra <peterz@infradead.org> - 2015-10-09 13:10 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Will Deacon <will.deacon@arm.com> - 2015-10-09 14:50 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Peter Zijlstra <peterz@infradead.org> - 2015-10-09 13:20 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Will Deacon <will.deacon@arm.com> - 2015-10-09 15:00 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Peter Zijlstra <peterz@infradead.org> - 2015-10-09 15:10 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation Peter Zijlstra <peterz@infradead.org> - 2015-10-09 13:20 +0200
Re: [PATCH v2] barriers: introduce smp_mb__release_acquire and update documentation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-09 19:30 +0200
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