Messages in this thread | | | Date | Sat, 01 Apr 2006 12:56:55 +1000 | From | Nick Piggin <> | Subject | Re: Synchronizing Bit operations V2 |
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Christoph Lameter wrote: > On Fri, 31 Mar 2006, Nick Piggin wrote:
>>You acknowledge that you have to fix ia64 to match current semantics >>first, right? > > > Right. I believe I have done so by making both smb_mb_* full barriers.
All bitop and atomic test_and_set, inc_return, etc etc (ie. everything that modifies the operand and returns something) needs to be a full barrier before and after too.
>>Now people seem to be worried about the performance impact that will >>have, so I simply suggest that adding two or three new macros for the >>important cases to give you a 90% solution. > > > We could transition some key locations of core code to use _mode bitops > if there are performance problems. > > >>I think Documentation/atomic_ops.txt isn't bad. smp_mb__* really >>is a smp_mb, which can be optimised sometimes. > > > Ok. Then we are on the same page and the solution I presented may be > acceptable. I have a new rev here that changes the naming a bit but I > think we are okay right?
Not sure, to be honest. I think it is probably something which needs input from all the other arch people, and Linus, if you intend to use it to introduce new types of barriers.
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