There's nothing wrong with adding BIO_META (for example) and other
hints in _principle_. You should be able to ignore it with no adverse
effects. If its not used by a filesystem (and there's nothing else
competing to use the same disk), I would hope to see the same
performance as other kernels which don't have it.
If the elevators are being changed in such a way that old filesystem
code which doesn't use new hint bits is running significantly slower,
surely that's blatant elevator regression, and that's where the bugs
should be reported and fixed?
-- Jamie
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