From: Peter Zijlstra <peterz@infradead•org>
To: Torsten Duwe <duwe@lst•de>
Cc: Tom Musta <tommusta@gmail•com>,
linux-kernel@vger•kernel.org, Paul Mackerras <paulus@samba•org>,
Anton Blanchard <anton@samba•org>,
Scott Wood <scottwood@freescale•com>,
"Paul E. McKenney" <paulmck@linux•vnet.ibm.com>,
linuxppc-dev@lists•ozlabs.org, Ingo Molnar <mingo@kernel•org>
Subject: Re: [PATCH] Convert powerpc simple spinlocks into ticket locks
Date: Fri, 7 Feb 2014 11:45:30 +0100 [thread overview]
Message-ID: <20140207104530.GG5126@laptop.programming.kicks-ass.net> (raw)
In-Reply-To: <20140207103139.GP5002@laptop.programming.kicks-ass.net>
On Fri, Feb 07, 2014 at 11:31:39AM +0100, Peter Zijlstra wrote:
> Anyway, what might work is something like (please forgive my ppc asm, I
> can barely read the thing, I've never before attempted writing it):
>
> lock:
> 1: lharx %0, 0, &head
> mov %1, %0
> addic %0, %0, 1
> stwcd %0, 0, &head
> bne- 1b
> 2: lhax %0, 0, &tail
That might need to be lhz too, I'm confused on all the load variants.
> lwsync
> cmp 0, %0, %0
cmp 0, %0, %1
So we compare the &tail load to the xadd return %1 above.
> bne- 2b
>
>
> unlock:
> lhz %0, 0, &tail
> addic %0, %0, 1
> lwsync
> sth %0, 0, &tail
>
next prev parent reply other threads:[~2014-02-07 10:45 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-06 10:37 [PATCH] Convert powerpc simple spinlocks into ticket locks Torsten Duwe
2014-02-06 15:53 ` Benjamin Herrenschmidt
2014-02-06 16:38 ` Peter Zijlstra
2014-02-06 17:37 ` Torsten Duwe
2014-02-06 18:08 ` Peter Zijlstra
2014-02-06 19:28 ` Tom Musta
2014-02-10 2:54 ` Benjamin Herrenschmidt
2014-02-07 8:24 ` Torsten Duwe
2014-02-06 20:19 ` Scott Wood
2014-02-07 9:02 ` Torsten Duwe
2014-02-07 10:31 ` Peter Zijlstra
2014-02-07 10:36 ` Peter Zijlstra
2014-02-07 10:45 ` Peter Zijlstra [this message]
2014-02-07 11:49 ` Torsten Duwe
2014-02-07 12:28 ` Peter Zijlstra
2014-02-07 15:18 ` Peter Zijlstra
2014-02-07 15:43 ` Peter Zijlstra
2014-02-07 17:08 ` Torsten Duwe
2014-02-07 17:19 ` Peter Zijlstra
2014-02-07 15:51 ` Kumar Gala
2014-02-07 16:10 ` Peter Zijlstra
2014-02-10 3:05 ` Benjamin Herrenschmidt
2014-02-10 3:02 ` Benjamin Herrenschmidt
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