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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 | |
| parent | 3dcb2a3fa5a0c903fd754bfba2b8defb9f191974 (diff) | |
| download | powerpc-74c504a6d70ab29b2c28bee62f5f39e3dd847ea2.tar.gz | |
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>
| -rw-r--r-- | arch/x86/events/intel/core.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index fcef678c342304..937363b803c19d 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -3323,8 +3323,19 @@ static int intel_pmu_hw_config(struct perf_event *event) return 0; } +#ifdef CONFIG_RETPOLINE +static struct perf_guest_switch_msr *core_guest_get_msrs(int *nr); +static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr); +#endif + struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr) { +#ifdef CONFIG_RETPOLINE + if (x86_pmu.guest_get_msrs == intel_guest_get_msrs) + return intel_guest_get_msrs(nr); + else if (x86_pmu.guest_get_msrs == core_guest_get_msrs) + return core_guest_get_msrs(nr); +#endif if (x86_pmu.guest_get_msrs) return x86_pmu.guest_get_msrs(nr); *nr = 0; |