This is a cut and paste from the current amd_iommu driver. I really have no idea if it's a good idea or not. It looks like joerg.roedel@xxxxxxx might be the person to ask. @Joerg Roedel should we keep this? On Mon, Apr 15, 2019 at 7:33 AM Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > > > +static void amd_iommu_flush_np_cache(struct iommu_domain *domain, > > + unsigned long iova, size_t size) > > +{ > > + struct protection_domain *dom = to_pdomain(domain); > > + > > + if (unlikely(amd_iommu_np_cache)) { > > Is this case really so unlikely that it needs a static branch prediction > hint?