From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Date: Fri, 31 Mar 2006 17:48:37 +0000 Subject: Re: Synchronizing Bit operations V2 Message-Id: <200603311948.38218.ak@suse.de> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Christoph Lameter Cc: Zoltan Menyhart , "Boehm, Hans" , "Grundler, Grant G" , "Chen, Kenneth W" , akpm@osdl.org, linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org On Friday 31 March 2006 19:45, Christoph Lameter wrote: > On Fri, 31 Mar 2006, Andi Kleen wrote: > > > Christoph Lameter writes: > > > MODE_BARRIER > > > An atomic operation that is guaranteed to occur between > > > previous and later memory operations. > > I think it's a bad idea to create such an complicated interface. > > The chances that an average kernel coder will get these right are > > quite small. And it will be 100% untested outside IA64 I guess > > and thus likely be always slightly buggy as kernel code continues > > to change. > > Powerpc can do similar things AFAIK. Not sure what other arches have > finer grained control over barriers but it could cover a lot of special > cases for other processors as well. Yes, but I don't think the goal of a portable atomic operations API in Linux is it to cover everybody's special case in every possible combination. The goal is to have an abstraction that will lead to portable code. I don't think your proposal will do this. -Andi