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| author | Wanpeng Li <[email protected]> | 2021-05-18 12:00:32 +0000 |
|---|---|---|
| committer | Paolo Bonzini <[email protected]> | 2021-05-27 11:45:52 +0000 |
| commit | 72b268a8e9307a1757f61af080e990b5baa11d2a (patch) | |
| tree | 3582e649e3f5d8da5f0fc99955a90407f903d609 /tools/testing/selftests/kvm/lib/perf_test_util.c | |
| parent | KVM: PPC: exit halt polling on need_resched() (diff) | |
| download | kernel-72b268a8e9307a1757f61af080e990b5baa11d2a.tar.gz kernel-72b268a8e9307a1757f61af080e990b5baa11d2a.zip | |
KVM: X86: Bail out of direct yield in case of under-committed scenarios
In case of under-committed scenarios, vCPUs can be scheduled easily;
kvm_vcpu_yield_to adds extra overhead, and it is also common to see
when vcpu->ready is true but yield later failing due to p->state is
TASK_RUNNING.
Let's bail out in such scenarios by checking the length of current cpu
runqueue, which can be treated as a hint of under-committed instead of
guarantee of accuracy. 30%+ of directed-yield attempts can now avoid
the expensive lookups in kvm_sched_yield() in an under-committed scenario.
Signed-off-by: Wanpeng Li <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Diffstat (limited to 'tools/testing/selftests/kvm/lib/perf_test_util.c')
0 files changed, 0 insertions, 0 deletions