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| author | Andrea Arcangeli <aarcange@redhat.com> | 2019-11-04 18:00:01 -0500 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2019-11-15 11:43:58 +0100 |
| commit | 74c504a6d70ab29b2c28bee62f5f39e3dd847ea2 (patch) | |
| tree | e182fad414ff5a6ea7d8d3e13996886c517f9bdf /arch/x86/kvm/x86.c | |
| parent | 3dcb2a3fa5a0c903fd754bfba2b8defb9f191974 (diff) | |
| download | lwn-74c504a6d70ab29b2c28bee62f5f39e3dd847ea2.tar.gz lwn-74c504a6d70ab29b2c28bee62f5f39e3dd847ea2.zip | |
x86: retpolines: eliminate retpoline from msr event handlers
It's enough to check the value and issue the direct call.
After this commit is applied, here the most common retpolines executed
under a high resolution timer workload in the guest on a VMX host:
[..]
@[
trace_retpoline+1
__trace_retpoline+30
__x86_indirect_thunk_rax+33
do_syscall_64+89
entry_SYSCALL_64_after_hwframe+68
]: 267
@[]: 2256
@[
trace_retpoline+1
__trace_retpoline+30
__x86_indirect_thunk_rax+33
__kvm_wait_lapic_expire+284
vmx_vcpu_run.part.97+1091
vcpu_enter_guest+377
kvm_arch_vcpu_ioctl_run+261
kvm_vcpu_ioctl+559
do_vfs_ioctl+164
ksys_ioctl+96
__x64_sys_ioctl+22
do_syscall_64+89
entry_SYSCALL_64_after_hwframe+68
]: 2390
@[]: 33410
@total: 315707
Note the highest hit above is __delay so probably not worth optimizing
even if it would be more frequent than 2k hits per sec.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/x86.c')
0 files changed, 0 insertions, 0 deletions