Adding a note that we must drop these patches for 5.0 (disco). The single queue IO schedulers are gone; blk-mq is the only game in town. For reference, this seems to be one of the key commits:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a1ce35fa49852db60fc6e268038530be533c5b15 I don't know if some of the patches are still useful or not. I'm going to drop them all; we can add some of them back if still needed. -- 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/1801305 Title: Restore request-based mode to xen-blkfront for AWS kernels Status in linux-aws package in Ubuntu: Fix Released Status in linux source package in Trusty: Fix Committed Status in linux-aws source package in Trusty: Fix Released Status in linux source package in Xenial: Fix Committed Status in linux-aws source package in Xenial: Fix Released Status in linux source package in Bionic: Fix Committed Status in linux-aws source package in Bionic: Fix Released Status in linux source package in Cosmic: Fix Committed Status in linux-aws source package in Cosmic: Fix Released Status in linux source package in Disco: Triaged Status in linux-aws source package in Disco: Fix Released Bug description: In current Ubuntu kernels, PV blkfront drivers have blk-mq enabled by default and cannot use the old I/O scheduler. [Impact] blk-mq is not as fast as the old request-based scheduler for some workloads on HDD disks. [Fix] Amazon Linux has a commit which reintroduces the request-based mode. It disables blk-mq by default but allows it to be switched back on with a kernel parameter. For X this needs a small patch from upstream for error handling. For B/C this patchset is bigger as it includes the suspend/resume patches already in X, and a new fixup. These are desirable as the request mode patch assumes their presence. [Regression Potential] Could potentially break xen based disks on AWS. For B/C, the patches also add some code to the xen core around suspend and resume, this code is much smaller and also mirrors code already in Xenial. [Tests] Tested by AWS for Xenial, and their kernel engineers vetted the patches. I tested the Bionic and Cosmic patchsets with fio, the system appears stable and the IOPS promised for EBS Provisioned IOPS disks were met in my testing. I did an apt update/upgrade and everything worked (no hash-sum mismatches). To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-aws/+bug/1801305/+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
