** Changed in: linux (Ubuntu Bionic)
Status: In Progress => Fix Committed
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https://bugs.launchpad.net/bugs/1755979
Title:
Cpu utilization showing system time for kvm guests (performance)
(sysstat)
Status in The Ubuntu-power-systems project:
In Progress
Status in linux package in Ubuntu:
Fix Committed
Status in linux source package in Artful:
In Progress
Status in linux source package in Bionic:
Fix Committed
Bug description:
== SRU Justification ==
All KVM guest cpu utilization is being reported as sys% time in the host.
It turns out Guest time accounting (CONFIG_VIRT_CPU_ACCOUNTING_GEN) has
been broken since v4.13 by commit 8b24e69fc47e436.
Commit 61bd0f66ff92 fixes this bug and is included in mainline as of
v4.16-rc5.
The commit was cc'd to upstream stable, but has not yet landed in upstream
4.15.
== Fix ==
61bd0f66ff92 ("KVM: PPC: Book3S HV: Fix guest time accounting with
VIRT_CPU_ACCOUNTING_GEN")
== Regression Potential ==
Low. Also cc'd to stable, so it has had additionl upstream review. Limited
to powerpc.
== Test Case ==
A test kernel was built with this patch and tested by the original bug
reporter.
The bug reporter states the test kernel resolved the bug.
== Comment: #0 - JENIFER HOPPER <[email protected]> - 2018-03-14 16:20:47 ==
+++ This bug was initially created as a clone of Bug #163375 +++
---Problem Description---
All KVM guest cpu utilization is being reported as sys% time in the host.
It turns out Guest time accounting (CONFIG_VIRT_CPU_ACCOUNTING_GEN) has been
broken since v4.13 by commit:
commit 8b24e69fc47e43679bb29ddb481aa0e8dce2a3c5
Author: Paul Mackerras <[email protected]>
Date: Mon Jun 26 15:45:51 2017 +1000
KVM: PPC: Book3S HV: Close race with testing for signals on guest
entry
---
That is now fixed and upstream accepted in Paulus' tree as git commit:
https://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc.git/commit/?h=kvm-ppc-fixes&id=61bd0f66ff92d5ce765ff9850fd3cbfec773c560
("KVM: PPC: Book3S HV: Fix guest time accounting with
VIRT_CPU_ACCOUNTING_GEN")
Please include this patch in Ubuntu so that guest cpu accounting is
correct.
Contact Information = [email protected]
---uname output---
Linux ltc-b114 4.15.0-10-generic #11-Ubuntu SMP Tue Feb 13 18:21:52 UTC 2018
ppc64le ppc64le ppc64le GNU/Linux
Machine Type = 5104-22C
---Debugger---
A debugger is not configured
---Steps to Reproduce---
Start a KVM guest, run something that generates cpu utilization in the
guest, observe mpstat on the host.
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