diff options
| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2019-10-27 16:19:38 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-11-12 11:44:20 +0100 |
| commit | b264f57fde0c686c5c1dfdd0c21992c49196bb87 (patch) | |
| tree | 2e77028b7799efca17bca51e4fe494f3aec6087f /arch/x86/hyperv | |
| parent | 83527ef7abf7c02c33a90b00f0954db35415adbd (diff) | |
x86/hyperv: Micro-optimize send_ipi_one()
When sending an IPI to a single CPU there is no need to deal with cpumasks.
With 2 CPU guest on WS2019 a minor (like 3%, 8043 -> 7761 CPU cycles)
improvement with smp_call_function_single() loop benchmark can be seeb. The
optimization, however, is tiny and straitforward. Also, send_ipi_one() is
important for PV spinlock kick.
Switching to the regular APIC IPI send for CPU > 64 case does not make
sense as it is twice as expesive (12650 CPU cycles for __send_ipi_mask_ex()
call, 26000 for orig_apic.send_IPI(cpu, vector)).
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
Link: https://lkml.kernel.org/r/20191027151938.7296-1-vkuznets@redhat.com
Diffstat (limited to 'arch/x86/hyperv')
| -rw-r--r-- | arch/x86/hyperv/hv_apic.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c index 5c056b8aebef..86c8674e92f4 100644 --- a/arch/x86/hyperv/hv_apic.c +++ b/arch/x86/hyperv/hv_apic.c @@ -194,10 +194,20 @@ do_ex_hypercall: static bool __send_ipi_one(int cpu, int vector) { - struct cpumask mask = CPU_MASK_NONE; + int vp = hv_cpu_number_to_vp_number(cpu); - cpumask_set_cpu(cpu, &mask); - return __send_ipi_mask(&mask, vector); + trace_hyperv_send_ipi_one(cpu, vector); + + if (!hv_hypercall_pg || (vp == VP_INVAL)) + return false; + + if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR)) + return false; + + if (vp >= 64) + return __send_ipi_mask_ex(cpumask_of(cpu), vector); + + return !hv_do_fast_hypercall16(HVCALL_SEND_IPI, vector, BIT_ULL(vp)); } static void hv_send_ipi(int cpu, int vector) |