arm64: KVM: Yield CPU when vcpu executes a WFE

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On an (even slightly) oversubscribed system, spinlocks are quickly
becoming a bottleneck, as some vcpus are spinning, waiting for a
lock to be released, while the vcpu holding the lock may not be
running at all.

The solution is to trap blocking WFEs and tell KVM that we're
now spinning. This ensures that other vpus will get a scheduling
boost, allowing the lock to be released more quickly. Also, using
CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT slightly improves the performance
when the VM is severely overcommited.

Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

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This commit is contained in:

Marc Zyngier 2013-08-02 11:41:13 +01:00

parent 4a10c2ac2f

commit d241aac798

3 changed files with 20 additions and 7 deletions

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8

arch/arm64/include/asm/kvm_arm.h

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1

arch/arm64/kvm/Kconfig

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18

arch/arm64/kvm/handle_exit.c

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