On Tuesday, June 10, 2008 12:05 pm Roland Dreier wrote: > > me too. That's the whole basis for readX_relaxed() and its cohorts: we > > make our weirdest machines (like altix) conform to the x86 norm. Then > > where it really kills us we introduce additional semantics to selected > > drivers that enable us to recover I/O speed on the abnormal platforms. > > Except as I pointed out before, Altix doesn't conform to the norm and > many (most?) drivers are missing mmiowb()s that are needed for Altix. > Just no one has plugged most devices into an Altix (or haven't stressed > the driver in a way that exposes problems of IO ordering between CPUs). > > It would be a great thing to use the powerpc trick of setting a flag > that is tested by spin_unlock()/mutex_unlock() and automatically doing > the mmiowb() if needed, and then killing off mmiowb() entirely.
Yeah I think that's what Nick's guidelines would guarantee. And Jes is already working on the spin_unlock change you mentioned, so mmiowb() should be history soon (in name only, assuming Nick also introduces the I/O barriers he talked about for ordering the looser accessors it would still be there but would be called io_wmb or something). Jesse _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
