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SubjectRe: [PATCH v2 5/6] KVM: sort memslots by its size and use line search
On 11/18/2011 11:19 AM, Xiao Guangrong wrote:
> Sort memslots base on its size and use line search to find it, so the larger
> memslots have better fit
>
> The idea is from Avi
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
> ---
> include/linux/kvm_host.h | 22 +++++++++---
> virt/kvm/kvm_main.c | 82 ++++++++++++++++++++++++++++++++-------------
> 2 files changed, 75 insertions(+), 29 deletions(-)
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index a0e4d63..83b396a 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -230,8 +230,12 @@ struct kvm_irq_routing_table {};
> #define KVM_MEM_SLOTS_NUM (KVM_MEMORY_SLOTS + KVM_PRIVATE_MEM_SLOTS)
> #endif
>
> +/*
> + * Note:
> + * memslots are not sorted by id anymore, please use id_to_memslot()
> + * to get the memslot by its id.
> + */
> struct kvm_memslots {
> - int nmemslots;
> u64 generation;
> struct kvm_memory_slot memslots[KVM_MEM_SLOTS_NUM];
> };
> @@ -307,9 +311,10 @@ static inline struct kvm_vcpu *kvm_get_vcpu(struct kvm *kvm, int i)
> (vcpup = kvm_get_vcpu(kvm, idx)) != NULL; \
> idx++)
>
> -#define kvm_for_each_memslot(slots, memslot, i) \
> - for (i = 0; i < (slots)->nmemslots && \
> - ({ memslot = &(slots)->memslots[i]; 1; }); i++)
> +#define kvm_for_each_memslot(slots, memslot, i) \
> + for (i = 0; i < KVM_MEM_SLOTS_NUM && \
> + ({ memslot = &(slots)->memslots[i]; 1; }) && \
> + memslot->npages != 0; i++)

You might allocate an always-empty memslot at the end and simplify the
termination condition.

>
> int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id);
> void kvm_vcpu_uninit(struct kvm_vcpu *vcpu);
> @@ -335,7 +340,14 @@ static inline struct kvm_memslots *kvm_memslots(struct kvm *kvm)
> static inline struct kvm_memory_slot *
> id_to_memslot(struct kvm_memslots *slots, int id)
> {
> - return &slots->memslots[id];
> + int i;
> +
> + for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
> + if (slots->memslots[i].id == id)
> + return &slots->memslots[i];
> +

Is that in any hot path? we could make an array for doing this translation.

Alex wants to increase the memslot count, so this could be a long loop.


--
error compiling committee.c: too many arguments to function



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