Re: Synchronizing Bit operations V2

From: Nick Piggin <nickpiggin_at_yahoo.com.au>
Date: 2006-04-01 13:16:51
Christoph Lameter wrote:
> On Fri, 31 Mar 2006, Chen, Kenneth W wrote:
> 
> 
>>>I think we could say that lock semantics are different from barriers. They 
>>>are more like acquire and release on IA64. The problem with smb_mb_*** is 
>>>that the coder *explicitly* requested a barrier operation and we do not 
>>>give it to him.
>>
>>I was browsing sparc64 code and it defines:
>>
>>include/asm-sparc64/bitops.h:
>>#define smp_mb__after_clear_bit()      membar_storeload_storestore()
>>
>>With my very naïve knowledge of sparc64, it doesn't look like a full barrier.
>>Maybe sparc64 is broken too ...
> 
> 
> Dave, how does sparc64 handle this situation?

It looks like sparc64 always expects paired smp_mb__* operations,
before and after the clear_bit.

-- 
SUSE Labs, Novell Inc.
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Received on Sat Apr 01 13:17:40 2006

This archive was generated by hypermail 2.1.8 : 2006-04-01 13:17:48 EST