From mboxrd@z Thu Jan  1 00:00:00 1970
From: compudj@krystal.dyndns.org (Mathieu Desnoyers)
Date: Thu, 22 Sep 2011 05:13:12 -0400
Subject: [ltt-dev] [URCU PATCH] atomic: provide seq_cst semantics
	on	powerpc
In-Reply-To: <4E7AE96A.8060307@redhat.com>
References: <1316502769-576-2-git-send-email-pbonzini@redhat.com>
	<20110920163518.GB31802@Krystal>
	<20110921235623.GI2394@linux.vnet.ibm.com>
	<20110922002712.GA8516@Krystal> <4E7AE96A.8060307@redhat.com>
Message-ID: <20110922091312.GB19151@Krystal>

* Paolo Bonzini (pbonzini at redhat.com) wrote:
> On 09/22/2011 02:27 AM, Mathieu Desnoyers wrote:
>> Paolo: if you are interested in optimising powerpc uatomic ops further,
>> add, sub, inc, dec, "or", "and", basically anything that is not
>> xchg/add_return/cmpxchg could use versions of the cmpxchg that does not
>> have the lwsync/sync barriers.
>
> Or they could just be rewritten in assembly with a manual ll/sc loop.

Sure, although I suspect the output assembly would be pretty much the
same if we share a common barrier-less permeable cmpxchg for all those
primitives on powerpc on modern compilers vs hand-coding each primitive.
I might be wrong though.

Thanks,

Mathieu

>
> Paolo
>

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com