SRU Request submitted:
https://lists.ubuntu.com/archives/kernel-team/2018-March/090973.html
** Description changed:
+ == 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]
-
+ 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
-
+
+ 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.
+ Start a KVM guest, run something that generates cpu utilization in the
guest, observe mpstat on the host.
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https://bugs.launchpad.net/bugs/1755979
Title:
Cpu utilization showing system time for kvm guests (performance)
(sysstat)
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