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Re: Memory barriers vs lock/unlock

From: Paolo Carlini <pcarlini at suse dot de>
To: Peter Dimov <pdimov at mmltd dot net>
Cc: libstdc++ <libstdc++ at gcc dot gnu dot org>
Date: Tue, 08 Nov 2005 22:06:46 +0100
Subject: Re: Memory barriers vs lock/unlock
References: <4370AEC8.4020504@suse.de> <007801c5e499$be267dd0$6401a8c0@pdimov2>

Peter Dimov wrote:

> When __exchange_and_add is implemented in terms of
> __sync_fetch_and_add, which seems to guarantee full ordering, there'll
> be no need for lock+unlock or explicit barriers.

Thanks a lot Peter, in particular for this last help! You know, we are
already using that implementation for quite a few targets (alpha, ia64,
powerpc, s390), very soon even inlined (see the last entries in the
audit trail of 24692) and we can easily implement this tweak in such cases.

Paolo.

References:
- Memory barriers vs lock/unlock
  - From: Paolo Carlini
- Re: Memory barriers vs lock/unlock
  - From: Peter Dimov

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