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Date: Thu, 22 Oct 2020 20:29:43 -0700 From: Josh Don <joshdon@...gle.com> To: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>, Juri Lelli <juri.lelli@...hat.com>, Vincent Guittot <vincent.guittot@...aro.org>, "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org> Cc: Dietmar Eggemann <dietmar.eggemann@....com>, Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, Mel Gorman <mgorman@...e.de>, Paolo Bonzini <pbonzini@...hat.com>, Eric Dumazet <edumazet@...gle.com>, linux-kernel@...r.kernel.org, netdev@...r.kernel.org, kvm@...r.kernel.org, Josh Don <joshdon@...gle.com>, Xi Wang <xii@...gle.com> Subject: [PATCH 2/3] kvm: better handling for kvm halt polling Add the new functions prepare_to_busy_poll() and friends to kvm_vcpu_block. The busy polling cpu will be considered an idle target during wake up balancing. cpu_relax is also added to the polling loop to improve the performance of other hw threads sharing the busy polling core. Suggested-by: Xi Wang <xii@...gle.com> Signed-off-by: Josh Don <joshdon@...gle.com> Signed-off-by: Xi Wang <xii@...gle.com> --- virt/kvm/kvm_main.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index cf88233b819a..8f818f0fc979 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2772,7 +2772,9 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) ktime_t stop = ktime_add_ns(ktime_get(), vcpu->halt_poll_ns); ++vcpu->stat.halt_attempted_poll; + prepare_to_busy_poll(); /* also disables preemption */ do { + cpu_relax(); /* * This sets KVM_REQ_UNHALT if an interrupt * arrives. @@ -2781,10 +2783,12 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) ++vcpu->stat.halt_successful_poll; if (!vcpu_valid_wakeup(vcpu)) ++vcpu->stat.halt_poll_invalid; + end_busy_poll(false); goto out; } poll_end = cur = ktime_get(); - } while (single_task_running() && ktime_before(cur, stop)); + } while (continue_busy_poll() && ktime_before(cur, stop)); + end_busy_poll(false); } prepare_to_rcuwait(&vcpu->wait); -- 2.29.0.rc1.297.gfa9743e501-goog
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