Alan Cox, on 11/13/2012 12:40 PM wrote:
Barriers are pretty much universal as you need them for power off !
I'm afraid, no storage (drives, if you like this term more) at the moment supports
barriers and, as far as I know the storage history, has never supported.
The ATA cache flush is a write barrier, and given you have no NV cache
visible to the controller it's the same thing.
The cache flush is cache flush. You can call it barrier, if you want to continue
confusing yourself and others.
Instead, what storage does support in this area are:
Yes - the devil is in the detail once you go beyond simple capabilities.
None of those details brings anything not solvable. For instance, I already
described in this thread a simple way how requested order of commands can be
carried through the stack and implemented that algorithm in SCST.
Vlad
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