Validation results. Proper number of vpus did show up in Bionic, Focal, Groovy, and Xenial-4.15. The Xenial 4.4 kernel only saw 256 vcpus.
ubuntu@ip-172-31-5-48:~$ uname -r && nproc 4.4.0-1121-aws 144 ubuntu@ip-172-31-5-48:~$ uname -r && nproc 4.4.0-1122-aws 256 ubuntu@ip-172-31-5-48:~$ uname -r && nproc 4.15.0-1094-aws 448 -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-aws in Ubuntu. https://bugs.launchpad.net/bugs/1913739 Title: aws: properly support instance types with > 255 cpu cores Status in linux-aws package in Ubuntu: New Status in linux-aws source package in Xenial: Fix Committed Status in linux-aws source package in Bionic: Fix Committed Status in linux-aws source package in Focal: Fix Committed Status in linux-aws source package in Groovy: Fix Committed Bug description: [Impact] To properly support instance types in AWS with > 255 cores we need to make sure that commit c40aaaac1018ff1382f2d35df5129a6bcea3df6b ("iommu/vt-d: Gracefully handle DMAR units with no supported address widths") is applied across all our linux-aws kernels. [Test Case] Tests performed by AWS. [Fix] Apply/backport commit c40aaaac1018ff1382f2d35df5129a6bcea3df6b. For groovy it's a clean cherry pick. For Focal/Bionic the backport activity is to simply rename the patched file. Only Xenial requires a little more backporting activity, in particular we need to change the condition in free_iommu() checking if iommu->iommu_dev is defined (instead of checking for iommu->iommu.ops, that is not available in the 4.4 kernel). [Regression potential] This change allows to use DMAR units that were not used before (for interrupt remapping). Theoretically this should provide a performance improvement, but we should keep an eye about potential performance regressions of drivers that are using IOMMU, in case they're using this new behavior incorrectly. Moreover, the Xenial backport required an adjustment in free_iommu() to check when we need to call iommu_device_destroy(), if the adjustment is not 100% correct we could introduce a potential memory leak. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-aws/+bug/1913739/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
