| Message ID | 20191104230001.27774-14-aarcange@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM monolithic v3 | expand |
On 05/11/19 00:00, Andrea Arcangeli wrote: > 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> > --- > arch/x86/events/intel/core.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c > index fcef678c3423..937363b803c1 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; > Queued, thanks. Paolo
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index fcef678c3423..937363b803c1 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;
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> --- arch/x86/events/intel/core.c | 11 +++++++++++ 1 file changed, 11 insertions(+)