The following commit has been merged into the x86/hyperv branch of tip:
Commit-ID: b264f57fde0c686c5c1dfdd0c21992c49196bb87
Gitweb: https://git.kernel.org/tip/b264f57fde0c686c5c1dfdd0c21992c49196bb87
Author: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
AuthorDate: Sun, 27 Oct 2019 16:19:38 +01:00
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Tue, 12 Nov 2019 11:44:20 +01:00
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@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Reviewed-by: Roman Kagan <rkagan@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20191027151938.7296-1-vkuznets@xxxxxxxxxx
---
arch/x86/hyperv/hv_apic.c | 16 +++++++++++++---
arch/x86/include/asm/trace/hyperv.h | 15 +++++++++++++++
2 files changed, 28 insertions(+), 3 deletions(-)
diff --git a/arch/x86/hyperv/hv_apic.c b/arch/x86/hyperv/hv_apic.c
index 5c056b8..86c8674 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)
diff --git a/arch/x86/include/asm/trace/hyperv.h b/arch/x86/include/asm/trace/hyperv.h
index ace464f..4d705cb 100644
--- a/arch/x86/include/asm/trace/hyperv.h
+++ b/arch/x86/include/asm/trace/hyperv.h
@@ -71,6 +71,21 @@ TRACE_EVENT(hyperv_send_ipi_mask,
__entry->ncpus, __entry->vector)
);
+TRACE_EVENT(hyperv_send_ipi_one,
+ TP_PROTO(int cpu,
+ int vector),
+ TP_ARGS(cpu, vector),
+ TP_STRUCT__entry(
+ __field(int, cpu)
+ __field(int, vector)
+ ),
+ TP_fast_assign(__entry->cpu = cpu;
+ __entry->vector = vector;
+ ),
+ TP_printk("cpu %d vector %x",
+ __entry->cpu, __entry->vector)
+ );
+
#endif /* CONFIG_HYPERV */
#undef TRACE_INCLUDE_PATH
|