Re: Truly lock-free multi-processor card marking

> I have searched in vain for several hours now, trying to find any  
> information for amd64/x86_64 about the minimum quantum that can be  
> written to without danger of the write being converted to read- 
> modify-write.  Any information, whether specific or general, is  
> much appreciated.

I think the answer is "it depends".  I have had good luck writing bytes,
but that was some years ago, and the envelope might be more pushed now.

You should probably write a test program that checks this; I was able
to quickly convince myself that a simple CMPXCHG (with no LOCK
prefix) was not adequate.

David Chase