On Fri, Jun 26, 2020 at 01:54:12PM -0700, Jonathan Lemon wrote: > On Fri, Jun 26, 2020 at 09:47:25AM +0200, Christoph Hellwig wrote: > > > > Note that this is somewhat urgent, as various of the APIs that the code > > is abusing are slated to go away for Linux 5.9, so this addition comes > > at a really bad time. > > Could you elaborate on what is upcoming here?
Moving all these calls out of line, and adding a bypass flag to avoid the indirect function call for IOMMUs in direct mapped mode. > Also, on a semi-related note, are there limitations on how many pages > can be left mapped by the iommu? Some of the page pool work involves > leaving the pages mapped instead of constantly mapping/unmapping them. There are, but I think for all modern IOMMUs they are so big that they don't matter. Maintaines of the individual IOMMU drivers might know more. > On a heavily loaded box with iommu enabled, it seems that quite often > there is contention on the iova_lock. Are there known issues in this > area? I'll have to defer to the IOMMU maintainers, and for that you'll need to say what code you are using. Current mainlaine doesn't even have an iova_lock anywhere.
