Re: [PATCH v5 4/8] KVM: Optimize kvm_make_vcpus_request_mask() a bit
From: Sean Christopherson <seanjc@google.com>
Date: 2021-09-03 16:22:55
Also in:
lkml
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();
...
quoted hunk ↗ jump to hunk
@@ -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;