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bh=q0cqoEHWoafdN/neNzYUeAZhdEpkcTz/8jBJYOGEWjQ=; b=MjdPA2i37KSVL9JuUpe6F7hgc2uCocfLNY70l6lcl73NMAR5ff33SIiH6q26C3k0MMbEWX kagjt6DZ97rfTYViECwQwDfGQSNWQ/9PxYSLtGFkTmQJXrfeNS6nHkMlPKzd9BoCk2B2vL VUYjxkYgeqFK5mtEUxXF8mZf/kssvn4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-528-yDgbhhxWNqOR-mR8eneedg-1; Wed, 27 Oct 2021 06:57:00 -0400 X-MC-Unique: yDgbhhxWNqOR-mR8eneedg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EAFF59F92B; Wed, 27 Oct 2021 10:56:56 +0000 (UTC) Received: from starship (unknown [10.40.194.243]) by smtp.corp.redhat.com (Postfix) with ESMTP id BEBD457CA5; Wed, 27 Oct 2021 10:56:44 +0000 (UTC) Message-ID: <4acc8c7fb3751be07953322a8334be140c2b153e.camel@redhat.com> Subject: Re: [PATCH v2 06/43] KVM: Refactor and document halt-polling stats update helper From: Maxim Levitsky To: Sean Christopherson , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Paul Mackerras , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Paolo Bonzini Date: Wed, 27 Oct 2021 13:56:43 +0300 In-Reply-To: <20211009021236.4122790-7-seanjc@google.com> References: <20211009021236.4122790-1-seanjc@google.com> <20211009021236.4122790-7-seanjc@google.com> User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Mailman-Approved-At: Wed, 27 Oct 2021 08:23:51 -0400 Cc: Wanpeng Li , kvm@vger.kernel.org, David Hildenbrand , linux-kernel@vger.kernel.org, Atish Patra , linux-riscv@lists.infradead.org, Claudio Imbrenda , kvmarm@lists.cs.columbia.edu, Joerg Roedel , kvm-ppc@vger.kernel.org, David Matlack , linux-arm-kernel@lists.infradead.org, Jim Mattson , Cornelia Huck , linux-mips@vger.kernel.org, kvm-riscv@lists.infradead.org, Vitaly Kuznetsov X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Fri, 2021-10-08 at 19:11 -0700, Sean Christopherson wrote: > Add a comment to document that halt-polling is considered successful even > if the polling loop itself didn't detect a wake event, i.e. if a wake > event was detect in the final kvm_vcpu_check_block(). Invert the param > to update helper so that the helper is a dumb function that is "told" > whether or not polling was successful, as opposed to determining success > based on blocking behavior. > > Opportunistically tweak the params to the update helper to reduce the > line length for the call site so that it fits on a single line, and so > that the prototype conforms to the more traditional kernel style. > > No functional change intended. > > Reviewed-by: David Matlack > Signed-off-by: Sean Christopherson > --- > virt/kvm/kvm_main.c | 20 +++++++++++++------- > 1 file changed, 13 insertions(+), 7 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 6156719bcbbc..4dfcd736b274 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -3201,13 +3201,15 @@ static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu) > return ret; > } > > -static inline void > -update_halt_poll_stats(struct kvm_vcpu *vcpu, u64 poll_ns, bool waited) > +static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start, > + ktime_t end, bool success) > { > - if (waited) > - vcpu->stat.generic.halt_poll_fail_ns += poll_ns; > - else > + u64 poll_ns = ktime_to_ns(ktime_sub(end, start)); > + > + if (success) > vcpu->stat.generic.halt_poll_success_ns += poll_ns; > + else > + vcpu->stat.generic.halt_poll_fail_ns += poll_ns; > } > > /* > @@ -3277,9 +3279,13 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) > kvm_arch_vcpu_unblocking(vcpu); > block_ns = ktime_to_ns(cur) - ktime_to_ns(start); > > + /* > + * Note, halt-polling is considered successful so long as the vCPU was > + * never actually scheduled out, i.e. even if the wake event arrived > + * after of the halt-polling loop itself, but before the full wait. > + */ > if (do_halt_poll) > - update_halt_poll_stats( > - vcpu, ktime_to_ns(ktime_sub(poll_end, start)), waited); > + update_halt_poll_stats(vcpu, start, poll_end, !waited); > > if (halt_poll_allowed) { > if (!vcpu_valid_wakeup(vcpu)) { Reviewed-by: Maxim Levitsky Best regards, Maxim Levitsky _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm