You have been subscribed to a public bug by Paride Legovini (paride): [ Impact ]
On Power9 the qemu based autopkgtest commands create VMs that are extremely slow and fail with obscure errors (partially discussed in LP: #1973628, comment 8). This can be reproduced for example by running: autopkgtest-buildvm-ubuntu-cloud -v -r jammy --ram-size 1024 but autopkgtest-virt-qemu is also affected. This happens because autopkgtest fails to detect the system architecture as KVM capable due to a typo in the architecture name (ppc64el instead of ppc64le). This upload fixes the typo. Fixing this bug in Jammy will allow users and developers to manually run autopkgtests on ppc64el. This is useful for example in +1 maintenance. [ Test Plan ] Run: autopkgtest-buildvm-ubuntu-cloud -v -r jammy --ram-size 1024 on an affected system. Buggy package => the command takes hours to complete and prints lots of obscure errors. Fixed package => the command completes in minutes. [ Where problems could occur ] Without this fix qemu based autopkgtest could in principle complete even when KVM is available (/dev/kvm exists) but broken, as it may be in some nested virtualization scenarios. This said, without KVM qemu based appears to be very broken due to timeouts caused by its extreme slowness, so I think the risk of causing a regression is marginal. [ Original Description ] On Power9 the qemu based autopkgtest commands create VMs that are extremely slow and fail with obscure errors (partially discussed in LP: #1973628, comment 8). This can be reproduced for example by running: autopkgtest-buildvm-ubuntu-cloud -v -r jammy --ram-size 1024 but autopkgtest-virt-qemu is also affected. The extreme slowness of the VMs made me think that something was off with the virtualization settings. I modified autopkgtest_qemu.py so that qemu-system-ppc64le is called with '-machine accel=kvm' (which I think is the same as '-machine pseries,accel=kvm' with pseries being the default machine type). With this change everything is very fast and reliable. These warnings also went away: qemu-system-ppc64le: warning: TCG doesn't support requested feature, cap-cfpc=workaround qemu-system-ppc64le: warning: TCG doesn't support requested feature, cap-sbbc=workaround qemu-system-ppc64le: warning: TCG doesn't support requested feature, cap-ibs=workaround qemu-system-ppc64le: warning: TCG doesn't support requested feature, cap-ccf-assist=on indicating that we were using TCG emulation before. I imagine that Qemu has good reasons not to default to accel=kvm or accel=kvm:tcg on ppc64, but think it's reasonable to assume it's available and enable it in autopkgtest. We can fix this in autopkgtest upstream, but it would be nice to verify if this is an issue with Debian too before submitting a salsa MR. [1] https://wiki.qemu.org/Documentation/TCG ** Affects: autopkgtest (Ubuntu) Importance: High Assignee: Paride Legovini (paride) Status: Fix Released ** Affects: autopkgtest (Ubuntu Jammy) Importance: High Assignee: Paride Legovini (paride) Status: In Progress ** Affects: autopkgtest (Debian) Importance: Unknown Status: Fix Committed ** Tags: ppc64el -- autopkgtest_qemu doesn't use accel=kvm on ppc64le, being fully unusable on that arch https://bugs.launchpad.net/bugs/1988527 You received this bug notification because you are a member of Canonical's Ubuntu QA, which is subscribed to the bug report. -- Mailing list: https://launchpad.net/~canonical-ubuntu-qa Post to : [email protected] Unsubscribe : https://launchpad.net/~canonical-ubuntu-qa More help : https://help.launchpad.net/ListHelp
