On Mon, 2015-03-23 at 21:44 -0400, David Miller wrote: > From: Benjamin Herrenschmidt <b...@kernel.crashing.org> > Date: Tue, 24 Mar 2015 09:21:05 +1100 > > > Dave, what's your feeling there ? Does anybody around still have > > some HW that we can test with ? > > I don't see what the actual problem is. > > Even if you use multiple pools, which we should for scalability on > sun4u too, just do the flush when allocation in _any_ pool wraps > around. > > That's still better than not doing the optimization at all.
I agree, I wasn't sure it was good enough for you, so was just putting other options on the table. > That is always going to be correct, and you can use a separate > spinlock to make sure only one thread of control does the full > IOMMU flush at a time. That would have to be done inside the of the flush callback but I don't see a big issue there. For the large pool, we don't keep a hint so we don't know it's wrapped, in fact we purposefully don't use a hint to limit fragmentation on it, but then, it should be used rarely enough that flushing always is, I suspect, a good option. Cheers, Ben. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
