** Changed in: linux (Ubuntu Cosmic)
Status: Fix Committed => Invalid
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https://bugs.launchpad.net/bugs/1829942
Title:
Address performance issue w/ GICv4-based guests
Status in linux package in Ubuntu:
In Progress
Status in linux source package in Cosmic:
Invalid
Status in linux source package in Disco:
Fix Committed
Status in linux source package in Eoan:
In Progress
Bug description:
[Impact]
Performance is degraded when a guest is booted w/ vgic v4 support enabled.
[Test Case]
I used a HiSilicon D06 system w/ an Intel 82599 10Gbps NIC. I passed through
a VF to a guest, and ran "netperf -H <host>" against a 10Gbps-capable target.
With vgic v4 support, I'm only seeing 5-6Gbps. With vgic v3 support, this was
in the 9Gbps spectrum. And, after applying the upstream fix, I'm also seeing
>9Gbps w/ vgic v4 enabled.
Note: to enable vgic v4 support, pass "kvm-arm.vgic_v4_enable=1" on
the host kernel cmdline.
[Fix]
ca71228b42a96 arm64: KVM: Always set ICH_HCR_EL2.EN if GICv4 is enabled
[Regression Risk]
The fix is restricted to the ARM/KVM subsystem.
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