KVM: X86: Dynamically allocate user_fpu

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After reverting commit 240c35a378 (kvm: x86: Use task structs fpu field
for user), struct kvm_vcpu is 19456 bytes on my server, PAGE_ALLOC_COSTLY_ORDER(3)
is the order at which allocations are deemed costly to service. In serveless
scenario, one host can service hundreds/thoudands firecracker/kata-container
instances, howerver, new instance will fail to launch after memory is too
fragmented to allocate kvm_vcpu struct on host, this was observed in some
cloud provider product environments.

This patch dynamically allocates user_fpu, kvm_vcpu is 15168 bytes now on my
Skylake server.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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This commit is contained in:

Wanpeng Li 2019-07-22 12:26:21 +08:00 • committed by Paolo Bonzini

parent e751732486

commit d9a710e5fc

4 changed files with 27 additions and 5 deletions

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2

arch/x86/include/asm/kvm_host.h

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13

arch/x86/kvm/svm.c

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13

arch/x86/kvm/vmx/vmx.c

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4

arch/x86/kvm/x86.c

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