From: Sean Christopherson <seanjc@google.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Nitesh Narayan Lal <nitesh@redhat.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
Eduardo Habkost <ehabkost@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 4/8] KVM: Optimize kvm_make_vcpus_request_mask() a bit
Date: Fri, 3 Sep 2021 16:22:47 +0000 [thread overview]
Message-ID: <YTJL1yOC2iwHwd9B@google.com> (raw)
In-Reply-To: <20210903075141.403071-5-vkuznets@redhat.com>
On Fri, Sep 03, 2021, Vitaly Kuznetsov wrote:
> Iterating over set bits in 'vcpu_bitmap' should be faster than going
> through all vCPUs, especially when just a few bits are set.
>
> Drop kvm_make_vcpus_request_mask() call from kvm_make_all_cpus_request_except()
> to avoid handling the special case when 'vcpu_bitmap' is NULL, move the
> code to kvm_make_all_cpus_request_except() itself.
>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
Reviewed-by: Sean Christopherson <seanjc@google.com>
> bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req,
> struct kvm_vcpu *except,
> unsigned long *vcpu_bitmap, cpumask_var_t tmp)
> {
> - int i, cpu, me;
> struct kvm_vcpu *vcpu;
> + int i, me;
> bool called;
Uber nit, if you're moving "int i, me;" to get reverse fir tree ordering, it
should be moved below "bool called;" as well, which you amusingly did do in the
below function :-)
>
> me = get_cpu();
>
...
> @@ -316,12 +323,23 @@ bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req,
> bool kvm_make_all_cpus_request_except(struct kvm *kvm, unsigned int req,
> struct kvm_vcpu *except)
> {
> + struct kvm_vcpu *vcpu;
> cpumask_var_t cpus;
> bool called;
> + int i, me;
next prev parent reply other threads:[~2021-09-03 16:22 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-03 7:51 [PATCH v5 0/8] KVM: Various fixes and improvements around kicking vCPUs Vitaly Kuznetsov
2021-09-03 7:51 ` [PATCH v5 1/8] KVM: Clean up benign vcpu->cpu data races when " Vitaly Kuznetsov
2021-09-04 0:52 ` Lai Jiangshan
2021-09-03 7:51 ` [PATCH v5 2/8] KVM: KVM: Use cpumask_available() to check for NULL cpumask " Vitaly Kuznetsov
2021-09-03 7:51 ` [PATCH v5 3/8] KVM: x86: hyper-v: Avoid calling kvm_make_vcpus_request_mask() with vcpu_mask==NULL Vitaly Kuznetsov
2021-09-03 7:51 ` [PATCH v5 4/8] KVM: Optimize kvm_make_vcpus_request_mask() a bit Vitaly Kuznetsov
2021-09-03 16:22 ` Sean Christopherson [this message]
2021-09-03 7:51 ` [PATCH v5 5/8] KVM: Drop 'except' parameter from kvm_make_vcpus_request_mask() Vitaly Kuznetsov
2021-09-03 7:51 ` [PATCH v5 6/8] KVM: x86: Fix stack-out-of-bounds memory access from ioapic_write_indirect() Vitaly Kuznetsov
2021-09-03 7:51 ` [PATCH v5 7/8] KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except() Vitaly Kuznetsov
2021-09-03 16:24 ` Sean Christopherson
2021-09-03 7:51 ` [PATCH v5 8/8] KVM: Make kvm_make_vcpus_request_mask() use pre-allocated cpu_kick_mask Vitaly Kuznetsov
2021-09-03 16:26 ` Sean Christopherson
2021-09-06 7:23 ` Vitaly Kuznetsov
2021-09-20 14:48 ` [PATCH v5 0/8] KVM: Various fixes and improvements around kicking vCPUs Vitaly Kuznetsov
2021-09-20 18:04 ` Paolo Bonzini
2021-09-24 11:05 ` Paolo Bonzini
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