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authorVitaly Kuznetsov <vkuznets@redhat.com>2019-10-27 16:19:38 +0100
committerThomas Gleixner <tglx@linutronix.de>2019-11-12 11:44:20 +0100
commitb264f57fde0c686c5c1dfdd0c21992c49196bb87 (patch)
tree2e77028b7799efca17bca51e4fe494f3aec6087f /arch/x86/hyperv/hv_apic.c
parent83527ef7abf7c02c33a90b00f0954db35415adbd (diff)
downloadlinux-b264f57fde0c686c5c1dfdd0c21992c49196bb87.tar.bz2
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/hv_apic.c')
-rw-r--r--arch/x86/hyperv/hv_apic.c16
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)