linux_dsm_epyc7002/arch/x86/include/asm/trace
Vitaly Kuznetsov b264f57fde 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
2019-11-12 11:44:20 +01:00
..
common.h x86/tracing: Disentangle pagefault and resched IPI tracing key 2017-08-29 11:42:29 +02:00
exceptions.h treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively 2019-04-09 14:19:06 +02:00
fpu.h x86/fpu: Defer FPU state load until return to userspace 2019-04-12 19:34:47 +02:00
hyperv.h x86/hyperv: Micro-optimize send_ipi_one() 2019-11-12 11:44:20 +01:00
irq_vectors.h x86/kernel: Fix more -Wmissing-prototypes warnings 2018-12-08 12:24:35 +01:00
mpx.h signal/x86: In trace_mpx_bounds_register_exception add __user annotations 2018-09-19 15:52:21 +02:00