Your message dated Fri, 05 Aug 2022 20:17:17 +0100
with message-id
<b4ef52ba579802678e1b437463282cc1e879eb5f.ca...@adam-barratt.org.uk>
and subject line Re: Bug#975269: buster-pu: package linux/TBD - arm64 stolen
time support
has caused the Debian Bug report #975269,
regarding buster-pu: package linux/TBD - arm64 stolen time support
to be marked as done.
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--
975269: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=975269
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--- Begin Message ---
Package: release.debian.org
Severity: normal
Tags: buster
User: [email protected]
Usertags: pu
X-Debbugs-Cc: [email protected]
There are two parts to the proposed changes:
1. Support in arm64 KVM code for reporting stolen time to guests.
2. Support in arm64 paravirtualised guest code for requesting stolen
time from the hypervisor and reporting it to user-space.
I think part 1 is not suitable for a stable update, but part 2 might
be.
[ Reason ]
Noah Meyerhans wrote in bug #969443:
> When used in virtual machine environments, Linux on amd64 is able to report
> "steal time" to the guest. This functionality has been supported by Linux
> on amd64 for years, but was only added to arm64 with Linux 5.5.
>
> As Debian and arm64 are increasingly used in virtual environments, including
> cloud environments, the ability to report steal time is increasingly
> important for system monitoring and performance analysis. Thus, I'd like to
> request that CPU steal time accounting support for arm64 be backported to
> buster, if possible.
[ Impact ]
Without this, it's difficult to determine when VM performance is being
affected by stolen time.
[ Tests ]
Noah has tested the changes (at least part 2) in an arm64 KVM
environment with steal time reporting, presumably AWS EC2.
[ Risks ]
There is a potential to regress VM host and/or guest support on arm64
and armhf, depending on which part(s) are applied.
[ Changes ]
1. * KVM: arm64: Document PV-time interface
* KVM: arm/arm64: Factor out hypercall handling from PSCI
* KVM: arm64: Implement PV_TIME_FEATURES call
* KVM: Implement kvm_put_guest()
* KVM: arm64: Support stolen time reporting via shared
* KVM: Allow kvm_device_ops to be const
* KVM: arm64: Provide VCPU attributes for stolen time
2. * arm/arm64: smccc/psci: add arm_smccc_1_1_get_conduit()
* arm/arm64: Provide a wrapper for SMCCC 1.1 calls
* arm/arm64: Make use of the SMCCC 1.1 wrapper
* arm64: Retrieve stolen time as paravirtualized guest
The actual patches are visible at
<https://salsa.debian.org/kernel-team/linux/-/merge_requests/268>.
Ben.
-- System Information:
Debian Release: bullseye/sid
APT prefers unstable-debug
APT policy: (500, 'unstable-debug'), (500, 'stable-updates'), (500,
'unstable'), (500, 'stable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 5.9.0-2-amd64 (SMP w/2 CPU threads)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled
--- End Message ---
--- Begin Message ---
On Thu, 2020-11-19 at 18:58 +0000, Ben Hutchings wrote:
> There are two parts to the proposed changes:
>
> 1. Support in arm64 KVM code for reporting stolen time to guests.
> 2. Support in arm64 paravirtualised guest code for requesting stolen
> time from the hypervisor and reporting it to user-space.
>
> I think part 1 is not suitable for a stable update, but part 2 might
> be.
>
Apologies for the fact that this somehow apparently never got a
response.
Given the timing, I think it probably makes more sense for this to be
part of an LTS update now.
Regards,
Adan
--- End Message ---
