benh> It might be sufficient to add a flush counter and compare it between runs benh> if actual wall-clock benchmarks are too hard to do (especially if you benh> don't have things like very fast network cards at hand). benh> benh> Number of flush / number of packets might be a sufficient metric, it..
I was just going to say: I can add those counters tomorrow, and get some stats, but seems like it doesn't really matter what the outcome is, because: On (03/23/15 21:44), 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. > > 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. --Sowmini _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
